By X. Grompel. Campbell University.
For example order gabapentin 600mg amex, the difference in results between Caughey and colleagues (1996) (a baseline comparison study) and Blok and colleagues (1997) (a group comparison study) is not accounted for by greater variability in measurements by the latter group cheap 600 mg gabapentin. Therefore, the study by Mølvig and colleagues (1991) showed some concurrence with that of Blok and colleagues (1997) and Caughey and colleagues (1996). Another alternative is to extrapolate from animal studies using model species that are known to have similar immune system components and responsiveness compared to humans. Detailed characterization of appro- priateness of animal models for extrapolation to humans with respect to immunosuppression has not been done. A few animal studies have shown the effects of dietary n-3 fatty acids on response to infection (Chang et al. The platelet count can decline by as much as 35 percent; however, the count does not usually fall below the lower limit of normal (Goodnight et al. Although prolonged bleeding times have been shown to be beneficial in preventing heart disease, bleed- ing times can become prolonged enough to result in excessive bleeding and bruising. Intervention studies that have examined the effects of n-3 fatty acids on bleeding time are mixed. None of the above studies reported excessive bleeding times, bleeding episodes, or bruising. Excessive cutaneous bleed- ing time and reduced in vitro platelet aggregability have been reported in Greenland Eskimos (Dyerberg and Bang, 1979; Dyerberg et al. A tendency to bleed from the nose and urinary tract was observed among the Greenland Eskimos (Bang and Dyerberg, 1980). Furthermore, ecologi- cal studies have suggested an increased risk of hemorrhagic stroke among Greenland Eskimos (Kristensen, 1983; Kromann and Green, 1980). A recent prospective study in the United States showed no association between intake of n-3 fatty acids and risk of hemorrhagic stroke (Iso et al. The median intake levels for the quintiles of n-3 polyunsaturated fat intake, however, ranged from only 0. The oxidative damage was shown to be reduced or prevented with the coconsumption of vitamin E (Ando et al. Studies on immune function were done in vitro and it is difficult, if not impossible, to know how well these artificial condi- tions simulate human immune cell response in vivo. Special Considerations A few special populations have been reported to exhibit adverse effects from consuming n-3 polyunsaturated fatty acids. Despite the favorable effects of n-3 fatty acids on glucose homeostasis, caution has been sug- gested for the use of n-3 fatty acids in those individuals who already exhibit glucose intolerance or diabetic conditions (Glauber et al. Increased episodes of nose bleeds have been observed in individuals with familial hypercholes- terolemia during fish-oil supplementation (Clarke et al. Anticoagu- lants, such as aspirin, warfarin, and coumadin, will prolong bleeding times and the simultaneous ingestion of n-3 fatty acids by individuals may exces- sively prolong bleeding times (Thorngren and Gustafson, 1981). During the early 1980s studies showed a hypercholesterolemic effect of trans fatty acids in rabbits (Kritchevsky, 1982; Ruttenberg et al. Renewed interest in the topic of hydrogenated fat in human diets, or more precisely trans fatty acid intake, started in the early 1990s. The availability of a methodology to distinguish the responses of individual lipoprotein classes to dietary modification expanded the depth to which the topic could be readdressed. Lipoprotein(a) (Lp(a)) concentrations in plasma have been associated with increased risk for developing cardiovascular and cerebrovascular disease, possibly via inhibition of plasminogen activity (Lippi and Guidi, 1999; Nielsen, 1999; Wild et al. Lp(a) concentrations have been reported by some investigators to be increased after the consumption of diets enriched in hydrogenated fat/trans fatty acids (Tables 8-9, 8-10, and 8-11) (Almendingen et al. The magnitude of the mean increases in Lp(a) concentrations reported to date that is associated with trans fatty acid intake for the most part would not be predicted to have a physiologically significant effect on cardiovascular disease risk. How- ever, an unresolved issue at this time is the potential effect of relatively high levels of trans fatty acids in individuals with initially high concentra- tions of Lp(a). The effect of trans fatty acids on hemostatic factors has been assessed by a number of investigators (Almendingen et al. In general, these researchers have concluded that hydrogenated fat/trans fatty acids had little effect on a variety of hemostatic variables. Similarly, Müller and colleagues (1998) reported that hemostatic variables were unaffected by the substitution of a vegetable oil- based margarine relatively high in saturated fatty acids when compared with a hydrogenated fish oil-based margarine. A few reports addressed the issue of trans fatty acid intake and blood pressure (Mensink et al. The authors concluded that consumption of diets high in saturated, mono- unsaturated, or trans fatty acids resulted in similar diastolic and systolic blood pressures. Because trans fatty acids are unavoidable in ordinary, nonvegan diets, consuming 0 percent of energy would require significant changes in patterns of dietary intake. It is possible to consume a diet low in trans fatty acids by following the dietary guidance provided in Chapter 11. Saturated Fatty Acids • Further examination of intakes at which significant risk of chronic diseases can occur is needed. Cis-Monounsaturated Fatty Acids • Information is needed to assess energy balance in free-living indi- viduals who have implemented a diet high in monounsaturated fatty acids versus a diet lower in monounsaturated fatty acids (and higher in carbohydrate).
Serum iron is low but ferritin is normal or ring of iron around the nucleus in erythrocyte pre- high 800 mg gabapentin for sale. Management Management Treating the underlying cause may result in a resolution Congenital sideroblastic anaemia may respond to pyri- of the anaemia buy discount gabapentin 100mg on-line. Primary acquired sideroblastic anaemia is treated as for myelodysplastic syndrome (see page Macrocytic anaemia 481). In secondary acquired sideroblastic anaemia any causative agent should be removed where possible. Macrocytic normoblastic anaemia Deﬁnition Normocytic anaemia Macrocytosis (large circulating red blood cells) are seen with normal erythrocyte progenitor cells in the bone Anaemia of chronic disease marrow (normoblasts). Deﬁnition Anaemia of chronic disease is a condition of impaired Aetiology/pathophysiology iron use where haemoglobin is reduced but iron stores Macrocytic normoblastic anaemia may be physiologi- are normal or high. The exact mechanism is not under- Deﬁnition stood, but there is often an increased lipid deposition in Megaloblastic anaemia is characterised by the presence the membrane of the red cells. Management Clinical features Any underlying cause should be treated where appropri- Symptoms and signs of anaemia (see page 467). Blood ﬁlm also reveals neutrophils r A loading dose of parenteral vitamin B is given to 12 with a hypersegmented nucleus. Serum vitamin B12 and the fasting patient to saturate plasma and liver redcell folate levels should be measured. Vitamin B deﬁciency r A high urinary excretion indicates a primary deﬁciency 12 of B12 intake, whereas a low urinary excretion Deﬁnition indicates malabsorption of B12, which should be Deﬁciency of vitamin B12 (cobalamins) causes macro- further investigated. If not, there is Vitamin B12 is found in animal products such as liver, malabsorption due to some other cause. Crohn’s disease), of treatment include hypokalaemia, gout and the un- pancreatic failure and following gastrectomy or small masking of iron deﬁciency. Vitamin causes failure of intrinsic factor production, vitamin B12 B12 is involved in nucleic acid synthesis (see Fig. Clinical features In addition to symptoms of anaemia, patients with vita- Age min B deﬁciency may have neurological complications More common in the elderly. The Schilling Aetiology/pathophysiology test is used to identify the cause of the deﬁciency (see The gastric parietal cells normally produce intrinsic fac- Table 12. Treatment is by vitamin B replacement, which may r 50% of patients have antibodies to intrinsic factor, 12 be given orally if due to dietary insufﬁciency or which are speciﬁc for this diagnosis and may be 472 Chapter 12: Haematology and clinical immunology blocking antibodies (bind to intrinsic factor and pre- deﬁciency is associated with neural tube defects in vents binding to B12)orbinding antibodies (bind to the fetus. Patients may also complain of a sore mouth and tongue (glossi- Clinical features tis). Patients may also have neurological complications of vitamin B Investigations 12 deﬁciency (see page 471). In many cases the cause is not obvious and further investigations may have to be Investigations undertaken including barium follow through or upper Full blood count will demonstrate a macrocytic anaemia gastrointestinal endoscopy and biopsy. The Schilling test is used to differentiate the causes of vitamin B12 deﬁciency Management (see Table 12. Prior to treatment with oral folic acid Management supplements, concurrent vitamin B12 deﬁciency must be Parenteral vitamin B12 replacement is required for life. Prophylaxis is advised in preg- reticulocytosis can be demonstrated 2–3 days after com- nancy, haemolytic anaemias, premature babies, dialysis mencing therapy. Causes of The causes of haemolytic anaemia are shown in Table folic acid deﬁciency: r 12. Low intake is most common in elderly, people living in poor social conditions and chronic alcoholics. Folic acid is found in fresh vegetables and meat, but may Pathophysiology be destoyed by overcooking. Shortening of the life span of red cells does not always r Malapsorption occurs due to small bowel disease (es- cause anaemia. If the increased loss can be compen- pecially if affecting the jejunum) such as coeliac dis- sated for by an up-regulation of the bone marrow (which ease. In addition to ditions, myeloproliferative disorders, other rapidly bone marrow up-regulation, reticulocytes (red cell pre- growing tumours and severe inﬂammatory disease. Haemolysis can In pregnancy there are increased requirements and be divided into two categories: Chapter 12: Haemoglobin disorders and anaemia 473 Table12. Inherited haemolytic anaemia Complications Achronically high serum bilirubin predisposes to the Hereditary spherocytosis formation of pigment gallstones. Chronic haemolysis predisposes to folate deﬁciency and thus levels should Deﬁnition be monitored and replacement given as required. Par- An autosomal dominant condition in which the red cells vovirus infections that cause a temporary bone marrow are spherical. Hereditary elliptocytosis is an autosomal failure may result in an aplastic crisis. Investigations r Haemolysis is suggested by a rise in bilirubin, high Incidence urinary urobilinogen (due to bilirubin breakdown Commonest inherited haemolytic anaemia; 1 in 5000. In intravascular haemolysis, red cell fragments are Aetiology/pathophysiology seen in the blood ﬁlm, whereas spherocytes may be There is a high new mutation rate with 25% of patients present in extravascular haemolysis. The underlying cause is cell life span can be demonstrated using labelled red aweakness in the link between the cytoskeleton and cells.
As a result of bet- ter public health measures such as water treatment and sewage disposal cheap 400mg gabapentin visa, and antibiotics generic 600 mg gabapentin amex, these are less of a problem today. He created the following postulates in an attempt to determine the relationship between the agent causing the illness and the illness itself. Second, when found it must be able to be isolated from the diseased host and grown in a pure culture. Next, the agent from the culture when introduced into a healthy host must cause the illness. Finally, the infectious agent must again be recovered from the new host and grown in a pure culture. While this model may work well in the study of acute infectious diseases, most modern illnesses are chronic and degenerative in nature. Illnesses such as dia- betes, heart disease, and cancer tend to be multifactorial in their etiology and usually have multiple treatments that can alleviate the illness. For these diseases, it is virtually impossible to pinpoint a single cause or the effect of a single treat- ment from a single research study. Stronger studies of these diseases are more likely to point to useful clinical information relating one particular cause with an effect on the illness. Applying contributorycause helps prove causation in these complex and mul- tifactorial diseases. However, since the disease-related factors are multifactorial, it is more difﬁcult to prove that any one factor is decisive in either causing or cur- ing the disease. Contributory cause recognizes that there is a large gray zone in which some of the many causes and treatments of a disease overlap. First, the cause and effect must be seen together more often than would be expected to occur by chance alone. This means that the cause and effect are asso- ciated more often than would be expected by chance if the concurrence of those two factors was a random event. If there were situations for which the effect was noted before the occurrence of the cause, that would negate this relationship in time. Finally and ideally, it should be shown that changing the cause changes the effect. This last factor is the most difﬁcult to prove and requires an intervention study be per- formed. Overall, contributory cause to prove the nature of a chronic and multi- factorial illness must minimally show association and temporality. However, to strengthen the causation, the change of the effect by a changing cause must also be shown. Causation and the clinical question The two main components of causation are also parts of the clinical question. You will learn to use good 22 Essential Evidence-Based Medicine Table 3. Cause and effect relationship for most common types of studies Type of study Cause Effect Etiology, harm, or risk Medication, environmental, Disease, complication, or or genetic agent mortality Therapy or prevention Medication, other therapy, or Improvement of symptoms preventive modality or mortality Prognosis Disease or therapy Time to outcome Diagnosis Diagnostic test Accuracy of diagnosis searching techniques so that you ﬁnd the study that answers this query in the best manner possible. The intervention, comparison, and outcome all relate to the patient population being studied. Primary clinical research studies can be roughly divided into four main types, determined by the elements of cause and effect. The nomenclature used for describing the cause and effect in these studies can be somewhat confusing and is shown in Table 3. They can also go in the other direction, starting from the presence or absence of the risk factor and ﬁnding out who went on to have or not have the outcome. Useful ways of looking at this category of studies is to look for cohort, Causation 23 case–control,orcross-sectional studies. In studies of etiology, the risk factor for a disease is the cause and the presence of disease is the outcome. In other studies, the cause could be a therapy for a disease and the effect could be the improvement in disease. There are special elements to studies of prognosis that will be discussed in Chapter 33. In general the clinical question can be written as: among patients with a particular disease (population), does the presence of a therapy or risk factor (intervention), compared with no presence of the therapy or risk factor (comparison), change the probability of an adverse event (outcome)? For a study of risk or harm, we can write this as: among patients with a disease, does the presence of a risk fac- tor, compared with the absence of a risk factor, worsen the outcome? We can also write it as: among patients with exposure or non-exposure to a risk factor, are they more likely to have the outcome of interest? For therapy, the question is: among patients with a disease, does the presence of an exposure to therapy, compared with the use of placebo or standard therapy, improve the outcome?
His research expertise is protein 800mg gabapentin with amex, amino acid cheap 100mg gabapentin mastercard, and energy metabolism in neonates and young adults, especially in patients suffering from cystic fibrosis. Luke’s– Roosevelt Hospital Center, and a professor of medicine at the College of Physicians and Surgeons, Columbia University. His research interests are in the hormonal control of carbohydrate metabolism, diabetes mellitus, obesity, and food intake regulation. Pi-Sunyer is a past president of the American Diabetes Association, the American Society for Clinical Nutri- tion, and the North American Association for the Study of Obesity. Pi-Sunyer is editor-in- chief of Obesity Research and associate editor of the International Journal of Obesity. Rand’s general expertise is in statistical modeling and application of statistics to biomedical problems. He was the recipient of several honors and awards and has served on many journal editorial boards. Reeds served as a permanent member of the Nutrition Study Section, National Institutes of Health and the International Review Panel, United Kingdom Agricultural and Food Research Council. Reeds’ research expertise was protein metabolism and amino acid requirements, specifically the regula- tion of growth and protein deposition by diet and other environmental variables such as stress and infection. Rimm is project director of a National Heart, Lung, and Blood Institute- and National Cancer Institute-funded prospective study of diet and chronic disease among men, as well as the principal investigator of a National Institute on Alcoholism and Alcohol Abuse study. Memberships include the Executive Committee of the Epidemiology and Prevention Council of the American Heart Asso- ciation and the Society for Epidemiologic Research. He has authored over 150 papers with a main research focus on the associations between diet and other lifestyle characteristics and the risk of obesity, diabetes, and cardiovascular disease. Department of Agriculture Human Nutrition Research Center on Aging at Tufts University. She is also a professor of nutrition in the School of Nutrition Science and Policy at Tufts and a professor of psychiatry and a scientific staff member in the Department of Pediatrics at Tufts University Medical School. Her research focus is infant and adult obesity, infant nutrient requirements, breastfeeding, and nutri- tion and aging. She chairs national meetings on dietary prevention of obesity and sits on international committees for evaluation of nutritional requirements. He has more than 100 scientific publications on food safety and risk assessment and has lectured nationally and internationally on these subjects. Rodricks is the author of Calculated Risks, a nontechnical introduction to toxicology and risk assessment. Her laboratory is actively involved in research on dietary fiber, phytoestrogens from flax and soy, and whole grains. Slavin has published more than 100 reviewed research articles and has given hundreds of nutrition semi- nars for professional and lay audiences. She is a science communicator for the Institute of Food Technologists and a member of numerous scientific societies, including the America Dietetic Association, the American Soci- ety for Nutritional Sciences, and the American Association for Cancer Research. She is a frequent source for the media on topics ranging from functional foods to sports nutrition. Her research interests are human nutrition, dietary fiber, nutrient bioavailability, sports nutrition, carbo- hydrate metabolism, and the role of diet in cancer prevention. He has served on the editorial board of the Journal of Nutrition, as program manager of the U. His research interests are dietary fiber and cholesterol and bile acid metabolism. Her special- ties within these areas are in social and economic determinates of health and nutrition, population-level indicators of risk, evaluation of public poli- cies in response to food insecurity, and the statistical analysis of dietary intake data at the individual and population levels. Tarasuk has served on several committees and advisory groups including the Nutrition Expert Advisory Group of the Canadian Community Health Survey, the External Advisory Panel for Food Directorate Review of Policies on the Addition of Vitamins and Minerals to Foods, the Expert Scientific Workshop to Evalu- ate the Integrated National Food and Nutrition Survey, the Advisory Baseline Study Group for the Canada Prenatal Nutrition Program, and the Nutrition Expert Group for the National Population Health Survey. Previously, he was Vice President for Corporate Research at Baxter-International and associate dean of the School of Medicine at West Virginia University. He has held professorships in the departments of pharmacology and toxicology in sev- eral medical schools including Iowa, Virginia, and West Virginia. He has authored over 12 textbooks and research monographs and has published over 350 scientific articles in the areas of endocrine pharmacology and reproductive toxicology. He is the recipient of several national awards including the Merit Award from the Society of Toxicology, Certificate of Scientific Services from the U. Environmental Protection Agency, and Distinguished Lecturer in Medical Sciences from the American Medical Association. Thomas serves as a specialty editor for Toxicology and Applied Pharmacology and is on the editorial board of Food and Chemical Toxicology.