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By W. Flint. Harrington College of Design.

The relation- ship between dietary fat intake and risk of colorectal cancer: Evidence from the combined analysis of 13 case-control studies order 20mg protonix with visa. Plasma lipid and lipoprotein responses to dietary fat and cholesterol: A meta-analysis discount protonix 40 mg mastercard. A prospective study of egg consumption and risk of cardiovascular disease in men and women cheap protonix 20mg otc. A controlled clinical trial with special reference to serum high- density lipoproteins. Whole-grain intake may reduce the risk of ischemic heart disease death in postmenopausal women: The Iowa Women’s Health Study. Relationship between dietary fiber and cancer: Metabolic, physi- ologic, and cellular mechanisms. Effects of low-fat, high-carbohydrate diets on risk factors for ischemic heart disease in postmenopausal women. Dietary fat and breast cancer in the National Health and Nutrition Examination Survey I. 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Identifying a departure from ‘usual’ buy protonix without a prescription, ‘natural’ or ‘expected’ levels of mortality or morbidity can be complex and measures need to be put in place to help this process discount protonix 20 mg without prescription. Many of the other sections of this Manual will help in identifying a disease problem [e protonix 40 mg without a prescription. Apparently healthy wildlife: identifying when a problem is emerging relies on a good understanding of what constitutes ‘normal’ mortality and morbidity and good early warning systems (Sally MacKenzie). Capacity requirements for identifying disease problems and informing early warning systems A good understanding of the use of the site by wild and domestic animals throughout the year and an understanding of their biology, abundance, behaviour and movements. A reasonable understanding of the epidemiology of particular diseases and of the stressors and other factors associated with disease outbreaks. Robust disease surveillance (both active and passive) in wildlife and livestock at a site. Ideally this should include regular visual checks of animal groups to screen for unusual behaviour, reduced body condition or productivity of domestic stock, signs of disease and/or mortality. Clear systems for reporting concern to a site manager and from the site manager to the local disease control authority. Use of these systems for immediate reporting of an unusual animal health problem to the local disease control authority. An understanding and capability to provide information and samples from a site to aid disease diagnosis [►Sections 3. A communication network established between surveillance diagnosticians, site managers and disease control authorities both for two-way information flow about surveillance at the site but also from authorities about disease in surrounding areas including neighbouring countries. A communication network between site users in particular farmers and those working and living within wetlands. Awareness amongst wetland stakeholders of disease issues and an understanding of how to respond if there is an apparent problem. Early identification of a disease problem and the ability to respond are dependent on clear and well established channels of communication and formal or informal networks. A problem disease may manifest itself in various subtle ways and a site manager should have available a communication network that allows rapid synthesis of seemingly disparate information. For example, a flow of information should allow a site manager to become aware that there has been a recent incursion of wildlife due to disturbance in surrounding areas, that there has been some loss of productivity in the livestock using the site, or that a higher than expected number of dead or sick wild animals has been observed. Although these may all be entirely unrelated it should prompt the site manager to investigate further. This sort of approach to disease intelligence is key as it supplements disease surveillance data by making full use of additional qualitative information, enhancing awareness of disease related issues that may otherwise remain undetected. Once a disease problem has been identified the response plan can then be put into action. Samples may include carcases, tissues, parasites, whole blood, serum, swabs, environmental material, faeces or ingested food etc. Choosing a specimen The most useful sample to collect is an entire carcase, which is fresh and undamaged by decomposition or scavengers. Such a sample allows a pathologist to carry out gross examination, take a variety of samples and perform a range of tests. It is important to note that carcases of certain species such as fish and aquatic invertebrates, decompose more rapidly than those of birds or mammals and, therefore, examination or chemical-fixation (e. Collection of both healthy and diseased tissue from the same chemically-fixed specimen for comparison can prove invaluable in certain circumstances (e. To help to reduce bias, samples should be representative of the range of species/individuals affected and several specimens of each species or class (e. Personal protective equipment The primary concern when collecting carcases or other diagnostic samples must be personal safety. Many animal diseases are zoonotic and every carcase or other diagnostic sample must be treated as a potential hazard to human health. Gloves (either plastic or disposable), coveralls, rubber boots and potentially masks, should be worn where possible and/or appropriate. If gloves are not available, inverted plastic bags can be used to protect the hands of the person collecting the carcase. Each carcase should be double-bagged whilst using gloves and coveralls and the outside of bags and footwear should be disinfected before leaving the area. Any other specimens should also be double-bagged in plastic before leaving the area. Disposable protective equipment should also be double-bagged and incinerated at high temperature where possible. Tissue collection If submitting an entire carcase for analysis is impractical, it may be necessary to remove appropriate samples from specimens. It is advisable to first consult disease specialists about the method they require for sample preservation. The collection of parasites and their preservation should also be discussed (most parasites can be preserved in 70% ethanol). It is valuable to become familiar with these specialists, their fields of expertise and potentially the sample preservation methods they prefer, before an emergency situation occurs. For most tissue samples the following is appropriate: with a sharp knife or scalpel cut a thin (3-6 mm) section of tissue. If lesions are present include all or part of this affected tissue and adjacent apparently healthy tissue. Take care not to crush the tissue and place in a volume of preservative at least ten times the volume of the tissue to ensure adequate preservation. Supplies Basic supplies and equipment required will vary depending on the species and samples in question. Samples can be stored in appropriately sized plastic bags with a sterile interior as they are easily transported and labelled. Photography Photographing the site and carcases in situ can be extremely helpful to a diagnostician. Photographing any lesions (both external and internal) can provide useful information on their position and appearance. Include a ruler or other readily recognised objects in the photograph to provide scale, and keep a written record of contextual information on each photograph. Labelling For maintaining sample identity, proper labelling of samples is vital, together with preventing loss of readability of labels or their separation from samples. Write directly onto sample tubes or keep labels as close to the specimen as possible. Double labelling is advisable, for example, directly label the sample or sample tube and also the bag in which the sample is placed. This helps prevent confusion and possible errors when multiple samples are received at the same laboratory. The most durable tags are those made of soft metal that can be inscribed with a pencil.

They are useful initial exploratory studies especially to screen or classify aspects of disease purchase discount protonix on line. They are only capable of demonstrating an asso- ciation between the cause and effect order protonix 40 mg mastercard. In order to draw conclusions from this study cheap protonix 40 mg overnight delivery, patient exposure to the risk factor being studied must continue until the outcome occurs. If the exposure began long before the outcome occurs and is intermittent, it will be more difficult to associate the two. If done properly, cross-sectional studies are capable of calculating the prevalence of disease in the population. Prevalence is the percentage of people in the population with the outcome of interest at any point in time. Since all the cases are looked at in one instant of time, cross-sectional studies cannot calculate incidence, the rate of appearance of new cases over time. Another strength of cross-sectional stud- ies is that they are ideal study designs for studying the operating characteristics of diagnostic tests. We compare the test being studied to the “gold standard” test in a cross-section of patients for whom the test might be used. The trade-off to the ease of this type of study is that the rules of cause and effect for contributory cause cannot be fulfilled. Since the risk factor and outcome are measured at the same time, you cannot be certain which is the cause and which the effect. A cross-sectional study found that teenagers who smoked early in life were more likely to become anxious and depressed as adults than those who began smoking at a later age. Does teenage smoking cause anxiety and depres- sion in later years, or are those who have subclinical anxiety or depression more likely to smoke at an early age? It is impossible to tell if the cause preceded the effect, the effect was responsible for the cause, or both are related to an unknown third factor called a confounding or surrogate variable. Confounding or surro- gate variables are more likely to apply if the time from the cause to the effect is short. For example, it is very common for people to visit their doctor just before their death. The visit to the doctor is not a risk factor for death but is a “surro- gate” marker for severe and potentially life-threatening illness. These patients visit their doctors for symptoms associated with their impending deaths. Prevalence– incidence bias is defined as a situation when the element that seems to cause an outcome is really an effect of or associated with that cause. This occurs when a risk factor is strongly associated with a disease and is thought to occur before 60 Essential Evidence-Based Medicine the disease occurs. Thus the risk factor appears to cause the disease when in reality it simply affects the duration or prognosis of the disease. The antigen was not a risk factor for the disease but an indicator of good prognosis. Longitudinal studies Longitudinal study is a catchall term describing either observations or interven- tions made over a given period of time. There are three basic longitudinal study designs: case–control studies, cohort studies, and clinical trials. These are ana- lytic or inferential studies, meaning that they look for a statistical association between risk factors and outcomes. Case–control studies These studies were previously called retrospective studies, but looking at data in hindsight is not the only attribute of a case–control study. There is another unique feature that should be used to identify a case–control study. The sub- jects are initially selected because they either have the outcome of interest – cases – or do not have the outcome of interest – controls. They are grouped at the start of the study by the presence or absence of the outcome, or in other words, are grouped as either cases or controls. This type of study is good to screen for potential risk factors of disease by reviewing elements that occurred in the past and comparing the outcomes. The ratio between cases and controls is arbitrar- ily set rather than reflecting their true ratio in the general population The study then examines the odds of exposure to the risk factor among the cases and com- pares this to the odds of exposure among the controls. The strengths of case–control studies are that they are relatively easy, cheap, and quick to do from previously available data. They can be done using current patients and asking them about events that occurred in the past. They are well suited for studying rare diseases since the study begins with subjects who already have the outcome. Each case patient may then be matched up with one or more suitable control patients. Ideally the controls are as similar to the cases as pos- sible except for the outcome and then their degree of exposure to the risk fac- tor of interest can be calculated. Case–controls are good exploratory studies and can look at many risk factors for one outcome. Unfortunately, there are many potentially serious weaknesses in case–control studies, which in general, make them only fair sources of evidence. Data often come from a careful search of the medical records of the cases and controls. The advantage of these records being easily available is counteracted by their questionable reli- ability. These studies rely on subjective descriptions to determine exposure and outcome, and the subjective standards of the record reviewers to determine the presence of the cause and effect. Implicit review of charts introduces the researcher’s bias in interpreting the measurements or outcomes. An explicit review only uses clearly objective measures in reviews of medical charts, or the chart material is reviewed in a blinded manner using pre- viously determined outcome descriptors. When a patient is asked to remember something about a medical condi- tion that occurred in the past, their memory is subject to recall or reporting bias. Recall or reporting bias occurs because those with the disease are more likely to recall exposure to many risk factors simply because they have the dis- ease. Another problem is that subjects in the sample may not be representative of all patients with the outcome. This is called sampling or referral bias and 62 Essential Evidence-Based Medicine commonly occurs in studies done at specialized referral centers. These referred patients may be different from those seen in a primary-care practice and often in referral centers, only the most severe cases of a given disorder will be seen, thus limiting the generalizability of the findings. When determining which of many potential risk factors is associated with an outcome using a case–control study a derivation set is developed. The results of the derivation set should be used cautiously since any association discovered may have turned up by chance alone.

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