Mark van der Laan PhD

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It is one of the most common causative agents of dermal hypersensitivity reactions among the general public gastritis cystica profunda definition rabeprazole 20 mg sale. The reactions usually follow contact with nickel-containing metal objects such as coins and jewelry gastritis hunger purchase rabeprazole 10 mg on line. Risk/benefit considerations the metals discussed in the previous section offer certain benefits because of their industrial and minor medical uses gastritis symptoms fatigue rabeprazole 10 mg purchase free shipping. However gastritis diet dog buy cheap rabeprazole 10 mg, they pose serious toxicological risks either to the population at large or specific Chapter twenty-five: Toxicity of metals 521 occupational workers gastritis diet ïîðåâî cheap rabeprazole uk. One group, the essential metals, is required in certain physiological functions and the other is used for a variety of medical purposes. Toxic metals the general population is at risk to these metals mainly through food. Tolerances, or equivalents, are established for various foodstuffs to ensure that the total intake will not exceed the amount that is considered acceptable from a toxicological point of view. Assuming a daily consumption of fish being 200 g, the intake of MeHg would not exceed 0. The safety is provided by the fact that most of the fish samples contain less MeHg than the 1 ppm permitted. The rationale was the availability of the exceptionally extensive data obtained from populations exposed to the full gamut of intake levels, ranging from "normal" to questionably poisoned, minimally poisoned, seriously poisoned, and fatally poisoned (Table 25. However, when a pregnant woman is exposed to high concentration of MeHg through seafood intake, it may increase the risk of having a miscarriage, or having a baby with deformities or severe nervous system diseases. Accordingly, the United States issued a national warning in 2001 recommending that pregnant women and infants limit their intake of fish, which was followed by similar warnings from Japan, United Kingdom, Canada, Australia, and Norway. On the other hand, fish is considered as an important source of nutrients, which should not be discarded for minimal or nonexistent risks. The intake was set on a weekly basis because fish is consumed, in many parts of the world, once a week. Similarly, targeted action has been taken with respect to cadmium in rice in Japan, where rice is the main source of this contaminant. Occupational workers are likely exposed to higher levels of toxic metals in mining, smelting, manufacturing, and similar occupations. Essential metals Selenium (Se) is a typical element that is toxic at high levels of intake while inducing a deficiency syndrome when the intake is too low. Human overexposure to selenium has been observed in China as well as in few isolated regions in the Americas. In animals overexposure induces more severe ill effects including retarded growth, liver necrosis, enlargement of the spleen and pancreas, anemia, and various disorders of reproductive function. Deficiency of selenium results in muscular dystrophy in sheep and cattle, exudative diathesis in chicken, and liver necrosis in swine and rats. In rats it may also produce reproductive failures, vascular changes, and cataracts. Selenium is a component of glutathione peroxidase, which is responsible for the destruction of H2O2 and lipid peroxides. Its function is, therefore, closely related to that of vitamin E, the biological antioxidant. This close relation is reflected in the fact that the minimal intake of selenium in rats is 0. It was only in the late 1970s that selenium was recognized as an essential element in humans. In certain regions in China, where selenium levels were low in soil and food, a special type of cardiomyopathy was noted. When they were given a sodium selenite supplement, the incidence of this endemic cardiopathy fell sharply. There is also an endemic osteoarthropathy observed in China, known as Kashin­Beck disease, and is believed to Chapter twenty-five: Toxicity of metals 523 be due to selenium deficiency; however, the evidence of its etiology is not as strong as that of Keshan disease. Selenium deficiency associated with muscular pain has been reported from New Zealand. For the general population, selenium exposure is essentially from food, especially cereals. The average daily intake of selenium of inhabitants in areas where there were cases of Keshan disease was about 0. It has been estimated that there is about a 100-fold margin between the highest no-toxic effect level and lowest level at which deficiency syndrome is avoided. For example, vitamin E deficiency increases toxicity as well as the physiological requirements of selenium, thus effectively reducing the margin. MeHg increases the effect of selenium deficiency, whereas inorganic mercury increases the toxicity of methylated selenium compounds. Further, because of the great individual variations in susceptibility resulting from host and environmental factors, it is not clear whether there is a dose that can be considered as devoid of deficiency as well as toxic effect on a population basis. Cobalt, copper, and iron are all essential metal elements required in normal development of erythrocytes. Iron is a component of hemoglobin, and copper facilitates the utilization of iron in the synthesis of hemoglobin. Cobalt is a component of vitamin B12, which is required in the development of erythrocyte. Excessive intake of cobalt results in polycythemia, an overproduction of erythrocytes, and cardiomyopathy. Overexposure to iron may result from excessive intake of metal or frequent blood transfusions. The excess iron is deposited as hemosiderin mainly in the liver, causing liver dysfunction. Iron binds to ambient air particles and is believed to be responsible for cardiovascular disturbances and increased morbidity associated with air pollutant exposure. In addition, iron binds to asbestos bodies and is believed to be associated with the observed asbestosis in humans. Certain iron industry workers have been reported to display pneumoconiosis and an increased lung cancer incidence associated with iron binding to particles and subsequent release. Acute oral poisonings have been noted after consuming improperly canned vegetable juices containing excessive amounts of copper and after taking large doses of iron supplement medications. Other essential metals include manganese (Mn) and molybdenum (Mo), which are cofactors in a number of enzyme systems such as phosphorylase, xanthine oxidase, and aldehyde oxidase. However, these metals are so plentiful in the human diet that no cases of deficiency syndrome have been reported. These metals have a variety of industrial uses, notably in making high-temperature-resistant steel alloys. Occupational exposure to manganese results in pneumonitis acutely, and encephalopathy chronically. Zinc is the cofactor in scores of metalloenzymes and is therefore an essential element. Deficiency of zinc thus induces a great variety of effects on the nervous system, hematopoietic system, skin, liver, eye, testis, and so forth. Zinc is readily excreted, and excessive intake by the oral route is thus unlikely to induce toxic effects. Metals used in medicine Therapeutic agents A number of metal compounds have been used in medicine. Those that are less toxic include compounds of aluminum as antacid, bismuth as astringent, gold for rheumatoid arthritis, lithium for mental depression, platinum complexes as antitumor agents, and thallium as depilatory agents. Other uses Aluminum in hemodialysis for chronic renal failure has resulted in fatal neurological syndrome. The use of barium (Ba) and gallium (Ga) used Chapter twenty-five: Toxicity of metals 525 in conjunction with x-rays, as a radiopaque agent and radioactive tracer has proven to be relatively safe. Therapeutic use of radiogallium has resulted in disease conditions related to radioactivity. Of special interest is titanium (Ti) since it is inert and resistant to corrosion, and thus it has been widely used in surgical and dental implants. It is present in trace amounts in a variety of foods of plant origin, and titanium dioxide has been used as a color additive because of its low toxicity. Subclinical levels of lead and developmental deficits: A multivariate follow-up reassessment. Developmental and reproductive toxicity of inorganic arsenic: Animal studies and human concerns. Arsenic species in drinking water, hair fingernails and urine of patients with blackfoot disease. Urinary cadmium levels predict lower lung function in current and former smokers: Data from the Third National Health and Nutrition Examination Survey. Cadmium alters the biotransformation of carcinogenic aromatic amines by arylamine N-acetyltransferase xenobiotic-metabolizing enzymes: Molecular, cellular, and in vivo studies. Toxicology and immunotoxicology of mercury: A comparative review in fish and humans. Unit risk estimates for airborne arsenic exposure: An updated view based on recent data from two copper smelter cohorts. Evaluation of Certain Food Additives and the Contaminants Mercury, Lead and Cadmium. Urinary porphyrins in patients with endemic chronic arsenic poisoning caused by burning coal in China. Association between prenatal lead exposure and blood pressure in female offspring. Toxic substances may originate from any one medium; however, they are generally transported to other media. The lead that enters humans is returned to the environment via excreta, refuse, dumps, incinerators, and so forth. Many other pollutants also have complex routes of environmental transport and affect humans. Air pollutants Introduction Past disasters Several episodes of severe air pollution affecting the health and lives of large numbers of people have been reported. One type occurred in winters, especially during the night, when domestic burning of coal was an important source of pollution, and the other occurred in summers, during daytime, when photo oxidation of automobile exhaust was the major source of pollutants. In either case, the meteorological conditions, low wind, and high barometric pressure kept the pollutants at ground level. The major effects were related to distress of respiratory and, to a lesser extent, cardiovascular systems. A number of deaths were reported from the air pollution episodes, either directly from the exposure to air pollutants or from strains on preexisting diseases or deficiencies in these systems (Waldbott, 1978). In the case of the London smog in 1952, there was an outbreak of a severe influenza epidemic, which could be attributed to the fraction of elevated mortality for this period (Bell et al. Current conditions As a result of these tragic events, measures have been taken to reduce the extent of air pollution. The most important anthropogenic source of ambient air pollutants in many developed nations is automobiles (Krewski and Rainham, 2007). Other sources include combustion (coal, natural gas, fuel oil, incineration of refuse, and wood stoves), metallurgical industry (see Chapter 25), and chemical industry (solvents, chemical intermediates, etc. The former includes sulfur dioxide, sulfuric acid, and sulfates; the latter includes finely divided solids and liquids. Thus, particles smaller than 10 m are suspended in air and are inhalable, as noted in Chapter 2. This is followed with thickening of the mucus layer in the trachea and hypertrophy of goblet cells. Respiratory functions are impaired, manifested by a decreased tidal volume, increased pulmonary resistance, and higher respiratory rate. Among exposed individuals, there is a rise in the incidence of respiratory tract infections, which may be attributable in part to an interference of the respiratory tract clearance mechanisms. Under normal conditions, this mechanism is responsible for removing bacteria and other particles from the tract. The effects of these sulfur pollutants are enhanced by the presence of suspended sulfur dioxide and smoke (suspended particulate matter) and produce deaths, especially among the elderly and those with preexisting diseases of the respiratory tract and heart, as those in Belgium (1930), Pennsylvania (1948), and London (1952). N2O is the most abundant among these chemicals, but is generated by anaerobic processes in the soil and surface layer of oceans, and hence is not an important air pollutant, as far as human health is concerned. However, their levels are low and they are not known to produce any harmful effects. Ozone is also a natural constituent of the upper atmosphere, formed by the photolysis of oxygen. The main sources of photochemical oxidants are automobiles and industrial combustion. Formaldehyde, which is one of the photochemical oxidants, will be discussed under the section "Indoor Air Pollutants/Sick Building Syndrome. This gas, therefore, passes through the upper respiratory tract to the terminal bronchioles and alveoli, where it forms nitric and nitrous acids. After inhalation exposure, ozone reacts with organic matter in the respiratory tract. The endothelia surrounding these structures are also damaged, resulting in pulmonary edema. Chronic exposure results in emphysema, atelectasis, focal necrosis, and sometimes bronchopneumonia. In the nasal mucosa, there is destruction of the epithelial lining and release of cytokines, and consequent inflammatory processes develop (Nikasinovic et al. Apart from their toxic effects on the respiratory tract, these air pollutants also produce eye irritation in adults (see Chapter 17). Recently, focus of air pollutants concentrated on neonates, infants, and children (Foos et al. It is well established that the lung is not mature and full development of architecture and functionality do not occur until age 18. Children have a larger lung surface area per kilogram and under normal circumstances, breathe a greater amount of air.

Mercury Lactational exposure of human infants to metals is a concern and raises the issue of risks versus benefits in the maintenance of the breastfeeding process chronic gastritis gas buy rabeprazole 10 mg line. Mercury (Hg) levels in milk are usually low (<1 ng/mL) gastritis symptoms breathing 20 mg rabeprazole with mastercard, but in environmental disasters such as in Minamata gastritis black stool generic 10 mg rabeprazole amex, Japan chronic gastritis symptoms uk buy rabeprazole online from canada, the levels reached 50 ng/mL gastritis vomiting blood 10 mg rabeprazole buy with mastercard. Numerous studies exist on the effects of either prenatal or during both pregnancy and postnatal exposure to metals on developing infants, but few reports are available on the consequences of the presence of metals exclusively in breast milk on children. Bearing in mind the consequences of methylmercury (MeHg) poisoning, especially in Minamata, Japan, consideration should be given to the contribution of lactational exposure to the observed neuronal disturbances in cases where nursing mothers, ingesting Hg-contaminated fish, were found to have severe neurological disorders in their infants (Matsumoto et al. Takeuchi (1968) clearly demonstrated the effects of epidemic MeHg exposure on fetal and newborn development. Industrial release of MeHg into Minamata Bay, followed by accumulation in edible fish and ingestion by lactating females, resulted in the transfer of metal to the suckling human infant. Maternal ingestion of Hg-contaminated food during pregnancy and lactation among fish-eating populations in Canada resulted in abnormal muscle tone and reflexes in boys only (McKeown-Eyssen et al. Although emphasis was placed on the consequences of prenatal exposure in the Canadian and New Zealand studies, the contribution of milk Hg to toxic outcome was neglected. It should be noted that in some patients with Minamata disease, the neurological symptoms did not develop at the time of exposure but years later. Further, the reported number of cases where children born in a Hg-contaminated area in Japan were healthy yet developed neuropathy in childhood. The contribution of breast milk Hg to late-onset Minamata disease remains to be resolved. Mammary transfer of MeHg to suckling infants has been reported to produce neurological lesions. This finding clearly indicates a positive correlation between exposure to high concentrations of metal in mammary tissue and toxicity in suckling infants. Although the precise contribution of mammary-derived MeHg to the observed adverse effects on neurological and behavioral changes in suckling pups is not known, it was found that postnatal exposure to this metal produced ocular defects. In contrast, there was a lack of an ocular effect in fetuses of prenatal exposed dams, suggesting that lactation methylmercury may in part contribute to the observed toxicity. It is well known that MeHg is secreted more readily in the maternal colostrum, the period during which eye defects are reported, and passes onto the suckling infant. Because milk contains essential nutrients for neurological and behavioral development, it is conceivable that less suckling and feeding would contribute to the Hg-induced nervous disorders, as there is less nutritional supply, and this is associated with delayed growth processes. Lead the content of Pb in human milk ranged from 5 to 68 ng/mL in a number of studies conducted in the United States and Europe, (Rabinowitz et al. In Mexico City, milk Pb levels reached 45 ng/mL (Berlin and Kacew, 1997; Berlin et al. It is not surprising that upon examination of the source of infant Pb intoxication, breast milk contained far less metal than either formula or environmental sources such as ceramic-leachable kitchenware, or paint chips (Rabinowitz et al. There is evidence to suggest a correlation between poor mental performance, as evidenced by the Bayley Infant Assessment Test, and increased Pb level (Needleman et al. These findings prompted Newman (1993) to recommend the promotion of breastfeeding, as human milk was a less suitable transmission vehicle for Pb contamination compared with formula feeding. Further, it should be stressed that the best source for daily nutrition among infants is human milk. In conditions of diets deficient in essential elements, Pb absorption and toxicity is enhanced in infants. Because breast milk is a source of Pb for suckling infants, it is conceivable that during irondeficiency anemia or calcium-deficient dietary intake in mothers, the bioavailability of milk Pb is increased, resulting in greater toxicity. Evidence suggests that Pb exposure may interfere with maternal metabolic pathways, resulting in decreased utilization of nutrients in the diet, and thus an absence of nutritional components present in milk. This altered milk composition will consequently adversely affect newborn development. Halogenated hydrocarbons Chemical exposure, via accidents and hazardous waste sites, resulted in toxicant accumulation in breast milk. The human maternal ingestion of a fungicide, hexachlorobenzene-treated wheat resulted in chemical accumulation in breast milk. Suckling infants subsequently developed symptoms of a disease, pembe yara, and a condition of prophyria cutanea tarda (Peters et al. Exposure to organophosphate pesticides such as chlorpyrifos and malathion is worthy of mention, as these compounds have been identified in breast milk (Berlin and Kacew, 1997). Ingestion of chlorpyrifos by a 3-year-old infant resulted in delayed polyneuropathy with transient bilateral vocal paralysis (Aiuto et al. Although lactation per se was not involved in this specific case, the importance lies in the fact that the manifestations of exposure did not occur until 1 to 3 weeks later. One should be aware that the consequences of lactational exposure to toxicants may also be delayed. This is supported by the reports of a mother who was exposed to 2,4-diphenoxyacetic acid (2,4-D) spray during pregnancy and lactation. Examination of the infant at 5 and 24 months of age revealed multiple malformations and severe mental retardation. Although mammary tissue content of 2,4-D was not determined, prolonged maternal exposure with consequent transmission to the infant was suggested as the cause of the observed toxicity. The fact that lactational-derived organophosphate pesticides alter suckling infant metabolism and that toxicity may be delayed suggests that breastfeeding in severe exposure conditions should be minimized. However, it is surprising that manifestations of toxicity in suckling infants following maternal organochlorine exposure have not been reported. This should not be considered proof that the presence of organochlorine contaminants in breast milk fails to affect the infant, as these environmental toxicants induce mammary carcinoma and may act as cocarcinogens. It is well known that suckling infants of cigarette smoking mothers are more prone to respiratory irritation and infections. However, cigarette smoking in the presence of atmospheric pollutants exerts an additive toxic effect on the mother. Conceivably, the presence of organochlorine compounds and nicotine in breast milk may increase infant toxicity as the hydrocarbons act as cocarcinogens. Hence, in susceptible suckling infants, these compounds may precipitate autoimmune diseases or lymphomas. This syndrome is associated with alcoholic women who drank heavily and chronically during pregnancy. Hence, alcohol in breast milk could worsen the already adverse infant development initiated during pregnancy. There are some studies inferring that alcohol exposure during lactation may increase the susceptibility of the infant to develop cancer (Infante-Rivard and El-Zein, 2007). Solvents the aromatic hydrocarbon toluene is utilized as a solvent or thinner in numerous industrial products including paints, glue, and resins. The lipophilic property of toluene is of interest in light of the physicochemical properties of breast tissue. There is no doubt that in utero exposure to toluene was manifested in teratogenesis. This is supported by the finding that obstructive jaundice developed in infants of lactating mothers exposed to the dry cleaning solvent perchloroethylene (Bagnell and Ellenberg, 1977). It is well established that exposure to the organic solvents during pregnancy results in toxemia and anemia. Unfortunately, infants born to these mothers were not followed clinically during lactation. However, as these environmental chemicals accumulate in breast milk and produce metabolic maternal alterations, it is conceivable that solvents may alter infant development. The release of organic solvents from breast milk fat needs to be considered among solvent abusers in light of adverse effects reported in children (Schreiber, 1997). Pharmacological agents In certain cases, nursing mothers are required to take medication during breastfeeding. Basically, all drugs transfer into breast milk and might potentially affect the breastfed infant/child, and efforts need to be made to minimize the risk by reducing drug exposure, with the lowest effective dose for the shortest duration. Several factors, such as pharmacokinetic and the intrinsic toxicity of the drug, could ultimately determine the risk of drug to breastfed infant/child. Drugs with greater inherent toxicity or high infant exposure are contraindicated during breastfeeding, as listed in Table 11. Drugs to avoid in the newborn and in infants less than 6 months of age, as suggested by Berlin and Briggs (2005), are also included in Table 11. Nevertheless, most medicines are considered to be compatible and may be used during breastfeeding, therefore the benefits and risks of treatment, in both nursing mother and the breastfed infant, need to be carefully considered (Berlin and Briggs, 2005). In guidance for the Lactation subsection of labeling for human prescription drug and biological products, the U. New Zealand Government, Medicines use in lactation, Prescriber Update 36, 22­5, 2015. Toxic effects on milk production Xenobiotics exposure of nursing mothers might alter the processes of milk production or excretion, that is, lactation. Potential targets for toxicological effects on the lactation system include development/maturation of the mammary tissue, milk secretion and/or regulation of hormones including Chapter eleven: Toxicology of lactation 247 oxytocin or prolactin (Hood, 2016). Several medications may also affect lactation system mediated by alterations in the level of prolactin. Dopaminergic antagonists, antihypertensive drugs, and antiemetic drugs are known to stimulate milk production through increased release of prolactin, while diuretics, dopaminergic agonists, and estrogen have been shown to decrease prolactin levels resulting in reduced secretion of milk (Coker and Taylor, 2010; Schaefer et al. Life-threatening organophosphateinduced delayed polyneuropathy in a child after accidental chlorpyrifos. Factors that influence the level of contamination of human milk with poly-chlorinated organic compounds. Criteria for chemical selection for programs on human milk surveillance and research for environmental chemicals. Influence of maternal diet during lactation and use of formula feeds on development of atopic eczema in high risk infants. Use of response biomarkers in milk for assessing exposure to environmental contaminants: the case for dioxin-like compounds. Evidence on the long-term effects of breastfeeding: Systematic reviews and meta-analyses. Physical and mental development of children with prenatal exposure to mercury from fish. Interviews and psychological tests at age 6, Solna, National Swedish Environmental Board, 112 (Report no. Environmental chemicals in human milk: A review of levels, infant exposures and health, and guidance for future research. Estimating infant mortality from human immunodeficiency virus and other causes in breastfeeding and bottle-feeding populations. Scleroderma like esophageal disease in children breastfed by mothers with silicone breast implants. Early diet of preterm infants and development of allergic or atopic disease: Randomized prospective study. Evidence for a protective effect of lactation on risk of breast cancer in young women: Results from a case-control study. Umbilical cord blood lead levels and neuropsychological performance at 12 months of age. Human immunodeficiency virus and other viruses in human milk: Placing the issues in broader perspective. Breast milk contamination and silicone implants: Preliminary results using silicon as a proxy measurement for silicone. Duration of lactation and incidence of myocardial infarction in middle to late adulthood. Detection of 2,4-dichlorophenoxyacetic acid (2,4-D) residues in neonates breastfed by 2,4-D exposed dams. Pregnancy, Lactation, and Reproductive potential: Labeling for Human Prescription Drug and Biological Products-Content and Format. Environmental chemicals: From the environment to food, to breast milk, to the infant. A survey of pregnant women having consumed rice oil contaminated with chlorobiphenyls and their babies. The latter types of substances are usually detoxified, but many of them may be bioactivated and become more toxic. Kupffer cells line the hepatic sinusoids and constitute an important part of the reticuloendothelial system of the body. The blood is supplied through the portal vein and hepatic artery, and it is drained through the central veins, followed by the hepatic vein into the vena cava. The main hepatic duct joins the cystic duct from the gall bladder to form the common bile duct, which drains into the duodenum. Approximately 50% of candidate compounds have produced hepatic effects at supra-therapeutic dose (Amacher, 1998). Hepatotoxicity is therefore considered one of the most life-threatening drug induced adverse outcomes. The toxicology of the liver is complicated by a variety of liver injuries and by different mechanisms through which the injuries are induced. Liver zonation and hepatotoxicity Zonation in the liver is categorized into zones 1, 2, and 3 based upon their position and oxygenation of hepatic lobules (50,000~100,000) as summarized in Table 12. Zone 1 is histologically located in the area where the oxygenated blood from hepatic arteries enters and O2 levels are high (Katz et al. On the other hand, zone 3 is located around central veins, low in O2 level, and highly susceptible to hypoxic agents leading to ischemic injury. In addition, differential expression of metabolic enzymes and proteins occurs in each zone and may contribute to the incidence of differential liver injury.

The onset gastritis diet fruit purchase rabeprazole with amex, location diet bei gastritis order rabeprazole with a mastercard, size gastritis zimt generic 10 mg rabeprazole visa, and growth of any unusual tissue masses needs to be carefully examined and recorded gastritis reddit rabeprazole 20 mg purchase overnight delivery. In addition gastritis diet nih discount rabeprazole 20 mg fast delivery, a number of organs need to be weighed, including the liver, kidneys, heart, testes, ovaries, and brain. Microscopic examinations need to be conducted on all tumor growths and all tissues showing gross abnormalities. Reporting of tumors As carcinogenesis can manifest itself in a variety of forms (see the section "Definition and Identification"), it is necessary to record the following: 1. Number of various types of tumors (both benign and malignant) and any unusual tumors 2. Onset of tumors whenever determinable Evaluation Preliminary assessment Chemical structure A number of chemicals are known to be carcinogenic. In addition, a large number of chemicals have been shown to be carcinogenic in animals (see the section "Genotoxic Carcinogens"). As chemicals that have structures similar Chapter eight: Carcinogenesis 185 to any of these or other carcinogens/mutagens are not necessarily carcinogens, they should nevertheless be assigned a high priority in carcinogenicity testing programs. In fact, certain chemical structures have been shown to be correlated with carcinogenicity (Ashby and Tennant, 1988). Amino substitutions diminished while bromine substitutions enhanced the carcinogenicity and extended the target tissues to the forestomach and lungs, as well as the kidneys and liver. The mutagenicity tests also provide information on the mode of action as well as on the question as to whether metabolic activation is required for the mutagenicity. Although positive results from these tests do not constitute positive evidence that the chemical is carcinogenic, they do indicate that extensive testing is required. Further, mutagenesis data are useful in the risk assessment of the chemical in question. Therefore, certain chemicals, such as cocarcinogens that yield negative results in mutagenesis tests, may be positive in these tests. Positive results from more than one of these limited carcinogenicity tests may be considered unequivocal qualitative evidence of carcinogenicity. Definitive assessment Data from well-designed and properly executed long-term carcinogenicity studies generally provide a reliable basis for assessment of carcinogenic potential. General considerations Results from these studies are generally more reliable than those from rapid screening tests. For example, too few animals surviving until tumor development may preclude statistical analysis of data. Tumor incidence As noted at the beginning of the chapter, carcinogenesis may manifest itself in one of four ways, or any combination thereof. The occurrence of unusual tumors is an important phenomenon if there are a significant number of them; when one or only a few of them are detected, further critical examination is required. An increase in the number of tumors per animal, without a concomitant elevation in tumor-bearing animals, usually indicates cocarcinogenicity only. The tumors in the experimental animals may not be at the same stage of development. The stages may include, for example, atypical hyperplasia, benign tumors, carcinomas in situ, invasion of adjacent tissues, and metastasis to other parts of the body. Although tumors of the same type but at different stages need to be separately tabulated, these should be combined for statistical analysis. Dose­response relationship Generally, a positive dose­response relationship is apparent. This phenomenon usually results from poor survival among these animals, which succumb to competing toxic effects of the chemical. Reproducibility of the results the confidence in a carcinogenicity study is enhanced if the results are produced in another strain of animals, as reproducibility in another species is even more significant. However, if negative results are obtained in another species, this fact may not nullify the positive findings but does justify further investigation. Evaluation of safety/risks the various approaches used in the evaluation of the safety/risk of carcinogens are discussed in Chapter 30. First, while the tests enumerated above are a valuable basis for risk/ safety assessment, other data relating to the mechanism of action and influences of modifying factors are also essential (U. The significant differences between genotoxic and nongenotoxic carcinogens are also considered as valid reasons for assessing their risks differently: it is generally presumed that genotoxic carcinogens exhibit no threshold, whereas nongenotoxic carcinogens induce cancer secondary to other biological effects Chapter eight: Carcinogenesis 187 which are likely to show no-effect dose levels. However, a chemical, such as chloroform, may act as an epigenetic as well as a genotoxic carcinogen. Further, there are chemicals with carcinogenicity secondary to noncarcinogenic biologic or physical effects that are elicited only at dose levels that could never be approached in realistic human exposure situations. There was general consensus that there are threshold doses for such secondary carcinogens (Lu, 1976; Munro, 1988). The response at such doses, therefore, may not be applicable to more realistic exposure conditions. Some carcinogens are active in a particular species, whereas others affect several species and strains of animals. All these factors must be taken into account in evaluating the safety/risk of carcinogens. The type of tumor observed needs to be taken into account if one is comparing rodent to human data, especially if the tumor is species-dependent and does not have relevance for humans. Finally, it is important to bear in mind that chemicals differ tremendously in their value to humans. For example, the use of a food color can often be suspended on the basis of suggestive carcinogenicity data. On the other hand, life-saving drugs, even when there is evidence of their carcinogenicity in humans, may still be used clinically. There are also environmental carcinogens, including those in food, that cannot be eliminated with present technology (see also Ames, 1989). The concentration of chemical is crucial in the decision making process if one is to ban a chemical due to its carcinogenic properties. This procedure has been applied to situations wherein human exposure to a particular carcinogen is suspected, for example, in the determination of exposure to aflatoxin B1 and its relationship to hepatocellular carcinoma (Qian et al. The changes include accumulation of plasminogen activator and increased prostaglandin synthesis. Biomarkers of susceptibility Individuals with certain genetic disposition may be more susceptible to carcinogenesis. Polymorphism of x-oxidation has been linked to susceptibility to colon cancer (Kadlubar et al. In the case of arsenic-induced carcinogenesis, polymorphism in the genes encoding the enzymes involved in the methylation of arsenic can lead to increased frequency of skin cancer (Steinmaus et al. Chapter eight: Carcinogenesis 189 Genetic polymorphisms in various metabolic enzymes were attributed to result in a higher frequency of benzene-induced carcinogenesis in China (Gu et al. Environmental pollution, natural carcinogens, and the causes of human cancer: Six errors. Chemical structure, Salmonella mutagenicity and extent of carcinogenicity among 222 chemicals tested in rodents by the U. An experimental study of the initiating stage of carcinogenesis, and a re-examination of the somatic cell mutation theory of cancer. Influence of functional group substitutions on the carcinogenicity of anthraquinone in rats and mice: Analysis of longterm bioassays by the National Cancer Institute and the National Toxicology Program. The origin and significance of hyperplastic hepatocellular islands and nodules in hepatic carcinogenesis. Mutations in the p53 tumor suppressor gene: Clues to cancer etiology and molecular pathogenesis. Rapid induction of mammary carcinoma in the rat and the influence of hormones on the tumors. Polymorphisms for aromatic amine metabolism in humans: Relevance for human carcinogenesis. Genetic and epigenetic cancer chemoprevention on molecular targets during multistage carcinogenesis. Mechanisms of hepatocarcinogenicity of peroxisome-proliferating drugs and chemicals. The significance of hepatic microsomal enzyme induction and altered thyroid function in rats: Implications for thyroid gland neoplasia. Guidance notes for analysis and evaluation of chronic toxicity and carcinogenicity studies. In: Chirurgical Observations Relative to the Cataract, the Polypus of the Nose, the Cancer of the Scrotum, the Different Kinds of Ruptures, and the Modification of the Toes and Feet. Is age an independent risk factor for chemically induced acute myelogenous leukemia in children A follow-up study of urinary markers of aflatoxin exposure and liver cancer risk in Shanghai, China. Carcinogenesis by hepatic peroxisome proliferators: Evaluation of the risk of hyperlipidemic drugs and industrial plasticizers to humans. Isoenzyme(s) of glutathione transferase (class mu) as a marker for susceptibility to lung cancer: A followup study. Roles of epidemiology, pathology, molecular biology, and biomarkers in the investigation of occupational lung cancer. Although spontaneous mutations and natural selection are the major means of evolution, in recent decades, a number of toxicants have been found to induce mutagenic effects in a variety of organisms. Electromagnetic fields and free radicals generated from electronic equipment/devices, medical devices. Some individuals exhibit mutations in skin cells or other tissues, termed somatic mutations. In contrast, germ mutations occur only in the sex cells and are more threatening because they are transmitted to subsequent generations. Health hazards in humans the hereditary effects of human exposure to these mutagenic substances cannot be ascertained at present. There are approximately 1000 dominant gene mutations responsible for various illnesses, including hereditary neoplasms such as bilateral retinoblastoma, and about the same number of recessive gene disorders such as sicklecell anemia, cystic fibrosis, and Tay­Sachs disease. The true effects of any additional mutagen in the environment can only be manifested after a lapse of several generations. The seriousness of this matter, therefore, warrants extensive investigations in Chapter nine: Mutagenesis 195 various fields of mutagenesis. It is also worth noting that various gene mutations and chromosomal abnormalities have been detected in human tumors. For example, patients with xeroderma pigmentosa are deficient in excision repair in the skin; they are susceptible to ultraviolet light and many chemical carcinogens and thus are prone to developing skin tumors. Those with ataxia telangiectasia have such deficiencies in the lymphoid system and are susceptible to x-rays and the carcinogen methyl nitro-nitrosoguanidine. Cockayne syndrome patients are also sun sensitive but exhibit distinctive congenital neurological and skeletal abnormalities, including mental deficiency and dwarfism (Nance and Berry, 1992). On the other hand, tests for mutagenicity have become more widely used in recent years because of their value as a rapid screening for carcinogenicity (see Chapter 8). This development stems mainly from the fact that most mutagens have been found to be carcinogens. Further, these tests, with a variety of endpoints, are useful in the elaboration of the mode of action of carcinogens. Categories of mutagenesis and their tests Attempts to identify human carcinogens by short-term tests began with the use of a bacterial mutagenesis assay. First, it transmits the genetic information from one generation of cells to the next through self-replication. Derangement of the bases, therefore, alters the amino acid content of the protein synthesized. In earlier studies, mutagenic activity was demonstrated mainly in fruit flies and onion root tips because of the simpler techniques involved. A nucleotide pair consists of one purine and one pyrimidine [adenine/ thymine (A­T) or guanine/cytosine (G­C)]. Nucleotide pairs are connected to a double helix molecule by sugarphosphate backbone linkages and hydrogen bonding. The helix must unwind to form templates at a rate of 3600 rpm to accommodate this replication rate. Because of the brevity of their description, at least one reference is cited for each test. It is worth noting that gene mutation may be detected in all organisms including bacteria. When the number of base pairs added or deleted is not a multiple of three, the amino acid sequence of the protein coded distal to the addition or deletion will be altered. This phenomenon is called frameshift mutation and is likely to affect the biological property of the protein. For a partial list of such chemicals, see discussions on procarcinogens in "Categories of Carcinogens" in Chapter 8. Transitions are interchanges of two-ring purines (A<->G) or of one-ring pyrimidines (C<->T): they therefore involve bases of similar shape. A series of new codons is formed distal to the deletion or insertion, and hence new amino acids in the protein synthesized. The imino tautomer of adenine can pair with cytosine, eventually leading to a transition from A-T to G-C (Table 9. Further, a protein synthesis termination codon may be formed, yielding a shortened protein.

Quantitative coronary angiographic studies of patients with angina pectoris and impaired glucose tolerance gastritis diet ôîòîñòðàíà order rabeprazole line. A study to find out the proportion of prediabetes in patients with acute coronary syndrome in a medical college of Kolkata gastritis pills buy cheap rabeprazole. Long-term clinical outcome in patients with acute coronary syndrome and dysglycaemia gastritis daily diet plan buy genuine rabeprazole online. High incidence of glucose intolerance in AsianIndian subjects with acute coronary syndrome gastritis drugs buy rabeprazole pills in toronto. Prediabetes and the association with unrecognized myocardial infarction in the multi-ethnic study of atherosclerosis gastritis stool cheap rabeprazole 20 mg mastercard. Impaired fasting glucose increases risk for an unrecognized myocardial infarction: the cardiovascular health study. At baseline and every 2 years, study participants underwent an extensive physical examination and lifestyle interview. The first preliminary results investigating mindfulness-based therapy for the treatment of chronic pain were published in 1982 by Kabat-Zinn [6]. Building upon the mindful meditation practices of Theravada Buddhism, Mahayana Buddhism, and yogic traditions, Kabat-Zinn designed a secular program for nonexperts or meditation novices to achieve a state of "detached self-observation," the opposite of concentration meditation [6]. In this way, pleasant and unpleasant sensations can be explored individually, noted, and dismissed and then move to the next without assigning a hierarchical classification or content value to it. Within the context of chronic pain, detached observation results in a learned recognition of the sensation while reducing the emotional and cognitive feelings associated with the experience, hurt, and suffering [6]. Upon final analysis, 65% reported a significant decrease in the severity of their chronic pain, and this was directly attributed to the program [6]. In the United States, 40% of the population use complementary therapies, including products. An epidemiological survey of patients with heart disease reported that 36% used complementary therapies in the previous 12 months [8]. A cautionary point is that the review and theory were based on studies that had inherent limitations regarding methodological quality. The role of mindfulness for the treatment of stress has been reviewed elsewhere (see [12]) and will not be addressed in this chapter. Each trial provided the control group with an active intervention unrelated to mindfulness. The difference in the number of days of abstinence is noteworthy considering that the mean baseline smoking rate was 13. Following randomization, 78 participants dropped out creating significant differences in baseline values between the two study groups. Although the results were promising, participants were not blinded to their randomly assigned study group that was attributed to the high attrition rate occurring between the periods of randomization and program initiation. In a third study by Davis and colleagues, the team ensured that the participants were blinded throughout, and the controls were provided with a similarly intensive program that also included a relaxation component unrelated to mindfulness [15]. The last study compared brief mindfulness (N = 20) with sham meditation (N = 17) each practiced for 20 min/day for 2 weeks [17]. There was no difference found with respect to either carbon monoxide or cotinine levels over the course of the study. The ecological momentary assessment data indicated that the mindfulness group benefited from a reduced overall negative effect of smoking and craving sensations in the time immediate following meditation. Smoking is a complex behavior requiring a wide array of cessation program options to appeal to the needs and interests of each smoker. As mindfulness is a nonpharmacological intervention that offers additional cognitive benefits to the practitioner and can be used in combination with other therapies. Unlike the smoking studies, usual care or wait-listed patients were commonly used as controls, blinding participants was not a priority, and the attrition rates were much lower. There was no significant between-group difference with respect to HbA1c levels at either 8th-week [21] or 6th-month [20] posttraining. The same cohort used in both studies had a male-to-female ratio of ~1:1 and a mean age of 53. With respect to glucose regulation, HbA1c analyses were restricted to the intervention groups. At the third-month posttraining, there were no significant decreases in HbA1c levels for either intervention even though the mean baseline values were high, 63. Although a favorable decreasing trend was found, the decreased amounts were not clinically meaningful. There were no betweengroup differences for these events and were attributed to events unrelated to the study. The small sample sizes of the two study groups require that this be repeated on a larger scale to obtain clinically relevant evidence. Comparing blood glucose levels from baseline to the end of the 8-week trial revealed no significant differences within or between the study groups. Interestingly, there were no between-group differences in changes with respect to diabetes-related stress response either. Only the walking and control groups experienced improvements in psychological response. Meanwhile, the authors noted significant within group changes in the vascular parameters. These parameters are important upstream contributors to the development of arteriosclerosis. The studies that assessed vascular factors noted improvements in response to the interventions in this patient population. The mindfulness intervention was generally well received by the participants and the studies had attrition rates within the anticipated ranges (Table 2). The participants were recruited from a low-income senior house community and had a mean age of 73 years; no details provided regarding gender. There were no significant differences at baseline with respect to ever-smoking status, education, race, heart rate, systolic blood pressure, and perceived stress. Of the 20 patients, 18 were on hypertensive medications at baseline with 3 being normotensive and 4 prehypertensive. Although participants had comorbid conditions, the most common were gastroesophageal reflux disease or high cholesterol. Multivariate regression results revealed noteworthy changes in both the systolic and diastolic blood pressure values between the groups. Participants were not receiving medications for hypertension during the study, and all had elevated blood pressure levels at baseline (systolic 120­139 mm Hg or diastolic 80­89 mm Hg) consistent with prehypertension. Otherwise, participants were healthy, nonsmokers without any comorbid conditions treated with medications known to alter blood pressure (M/F 4:6, mean age 50. Significant between-group differences were seen for both systolic and diastolic blood pressure rates with the intervention group benefiting from greater improvement than controls. The more robust measure of 24 h ambulatory blood pressure monitoring found no significant difference between the groups. The attrition rate was 7 (25%) and 11 (40%) for the intervention and control groups, respectively. All participants were diagnosed with stage 1 hypertension according to 24 h ambulatory blood pressure monitoring; none were taking hypertension-related medications. No significant differences were identified either within or between the study groups. Overall, 14 participants failed to complete the 12-week clinical trial of which 10 were in the control. Mindfulness-Based Therapy and Heart Health Chapter 23 281 the contradictory results of the three studies reviewed fail to inform if mindfulness training improves blood pressure in the setting of prehypertension or hypertension. In clinic, blood pressure monitoring is known to create an artificial increase in rates due to the "white coat" effect where patients are ill at ease in unfamiliar surroundings [28]. This effect may have contributed to the significant changes recorded in the Palta et al. Blom and colleagues observed that significant improvements associated with cognitive or mindfulness training were reported in studies where the participants were taking blood pressure medication apart from one study [27]. They theorized that the intervention improved patient compliance with their medication regimens, thereby resulting in improved blood pressure levels. This explanation does not address the significant changes in the unmedicated prehypertensive population trial by Hughes et al. The variation in trial design, follow-up times, and participant eligibility makes it challenging to identify let alone quantify clinically relevant benefits of mindfulness in hypertension. A review and meta-analysis of meditation and blood pressure concluded that mindfulness affords practitioners with statistically significant systolic and diastolic improvements for hypertensive and normotensive individuals [29]. The authors highlighted the need for large-scale, well-designed trials and the use of 24 h ambulatory blood pressure monitoring. Future research needs to also focus on identifying the mechanism(s) by which meditation effects physiological changes that can alter blood pressure. The underlying causes of excess body weight are complex and can involve reward-driven eating behaviors or psychological stress, such as acute isolated or chronic ongoing stressors [30]. Mindfulness-based training has proved promising in helping individuals overcome challenging behaviors and patterned conditioning. The mainstays of studies in this area have focused on assessing the efficacy of mindfulness, either alone or in combination with other programming, to achieve and maintain weight loss. As reviewed by Katterman and colleagues, both emotional eating and binge eating respond favorably to mindfulness-based meditation practices, although the effect on significant and sustained weight loss is inconclusive [32]. The importance of adhering to a program intended to change food behaviors is not compelling when the participant is not at risk. As well, findings from such studies are not clinically relevant if obtained in a population different than the target. The estimated effects favored the intervention (N = 100) over the control group coupled with an extra weight loss of 1. An overall 24% attrition rate was noted; those who were in the intervention group had little interest in mindfulness and lower expected outcomes that led to their dropping out. The authors commented in favor of participant self-assignment to one of the two study groups as this may be a more pragmatic approach reflective of the real world while offering a higher study completion rate for research purposes. At the 12th month, one group continued losing weight, while the other began to regain weight. As a lifestyle behavior, mindfulness has the potential to improve eating habits especially if driven by negative emotions, such as anxiety or depression. To date, studies have preferentially focused on weight loss trials rather than improving nutritional quality [11]. At the third-month postintervention, each group had significant improvements in depressive symptoms, outcome expectations, nutrition and eating-related self-efficacy, and food-oriented cognitive control. The controls had significantly greater improvements in nutrition knowledge and intake of fruits and vegetables. The authors suggested that offering the two programs separately or in combination could provide patients with valuable choices by which they could meet their personal self-care needs. At present, it is inconclusive if mindfulness-based programming improves physical activity in individuals leading sedentary lifestyles. The questions being addressed by these studies, for the most part, remain unanswered. Here, the high attrition rates render the studies underpowered rather than inherent issues with methodological rigor. This primarily self-reported outcome is consistent with the literature suggesting that mindfulness is beneficial for some and is not detrimental to any. In that sense, the universality and low cost of mindfulness relative to pharmacological treatments make it attractive for future study. An outpatient program in behavioral medicine for chronic pain patients based on the practice of mindfulness meditation: theoretical considerations and preliminary results. The clinical significance and costs of herbs and food supplements used by complementary and alternative medicine for the treatment of cardiovascular diseases and hypertension. Effectiveness of mindfulness-based stress reduction and mindfulness based cognitive therapy in vascular disease: a systematic review and meta-analysis of randomised controlled trials. Mind-body practices for patients with cardiac disease: a systematic review and meta-analysis. Mindfulness and cardiovascular disease risk: state of the evidence, plausible mechanisms, and theoretical framework. Meditation programs for psychological stress and well-being: a systematic review and meta-analysis. Pilot randomized trial on mindfulness training for smokers in young adult binge drinkers. Randomized trial on mindfulness training for smokers targeted to a disadvantaged population. Finding the right match: mindfulness training may potentiate the therapeutic effect of nonjudgment of inner experience on smoking cessation. Effect of brief mindfulness practice on self-reported affect, craving, and smoking: a pilot randomized controlled trial using ecological momentary assessment. Mindfulness training for smoking cessation: results from a randomized controlled trial. Mindfulness-based cognitive therapy for people with diabetes and emotional problems: long-term follow-up findings from the DiaMind randomized controlled trial. The effects of a mindfulness-based intervention on emotional distress, quality of life, and HbA(1c) in outpatients with diabetes (DiaMind): a randomized controlled trial. Individual mindfulness-based cognitive therapy and cognitive behavior therapy for treating depressive symptoms in patients with diabetes: results of a randomized controlled trial. Long-term effects of individual mindfulness-based cognitive therapy and cognitive behavior therapy for depressive symptoms in patients with diabetes: a randomized trial. Comparison of the effects of Korean mindfulness-based stress reduction, walking, and patient education in diabetes mellitus.

10 mg rabeprazole buy with amex. Dr. Rhonda Patrick Explains the Cause of Heart Disease.

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