September 19, 2002
Environmental Exposure to Endotoxin and Its Relation to Asthma
Children with asthma have both a genetic predisposition to the condition and environmental exposure that modifies the genetic factors. It is known that children of elementary-school age who live on a farm are less likely to have asthma than their counterparts from nonfarming households. In this study of children from parts of Austria, Germany, and Switzerland where there were both farming and nonfarming households, the investigators related the level of exposure to endotoxin, determined by sampling dust from the mattresses where the children slept, to the prevalence of asthma and related conditions. The greater the endotoxin exposure, the less likely it was that children had asthma. These findings indicate that exposure to endotoxin, which activates the innate immune response, appears to have a key modulatory role in the expression of asthma. This study focuses research on the identification of this protective factor in the environment; the lack of this factor may be responsible for the current epidemic of asthma.
|
|||||
Among 7814 participants in the Framingham Heart Study who were followed for an average of 17 years, 822 had at least one episode of syncope, and the incidence of a first report of syncope was 6.2 per 1000 person-years. Vasovagal and cardiac causes were most common; the cause was not identified in over a third of cases. Mortality was increased among all participants with syncope, among those with syncope of unknown cause, and particularly among those with cardiac syncope, as compared with participants who did not have syncope. Vasovagal syncope had a benign prognosis. In a community-based population, syncope that is not due to a vasovagal event or to another defined benign cause is a marker of an increased risk of death.
|
|||||
Heritability of Mammographic Density, a Risk Factor for Breast Cancer
Mammographic images can be dark due to the presence of fat or light due to radiologically dense connective and epithelial tissue. The overall percentage of dense areas in the image is the measure of mammographic density. Previous work has shown that a dense mammographic pattern is associated with an increased risk of breast cancer. This study involving 571 pairs of monozygotic twins and 380 pairs of dizygotic twins found a high degree of heritability of mammographic density. Genetic factors most likely play an important part in susceptibility to breast cancer, but apart from mutations in BRCA1 and BRCA2, little is known about possible susceptibility alleles. This large study in twins points to important clues lying within the composition of the breast itself.
|
|||||
Hemofiltration and Peritoneal Dialysis in Infection-Associated Acute Renal Failure in Vietnam
In developing nations, infection-associated acute renal failure is associated with high morbidity and mortality. This open, randomized trial from Vietnam compared peritoneal dialysis, widely used in patients with this condition (with falciparum malaria or sepsis), with hemofiltration. Resolution of acidosis and a decrease in the serum creatinine concentration occurred more than twice as rapidly in the group assigned to hemofiltration, and renal-replacement therapy was required for a shorter period. Survival was improved in the group assigned to hemofiltration. Hemofiltration is superior to peritoneal dialysis for infection-associated acute renal failure.
|
|||||
Tinnitus is a common but poorly understood disorder that has a strong association with aging. This review explains how to differentiate subjective from objective tinnitus. Although tinnitus is often associated with hearing loss, in many cases the origin may be central. Multiple treatment options may help in the management of this chronic condition.
|
|||||
Mechanisms of Disease: Effect of Infectious Diseases on Susceptibility to Autoimmune and Allergic Diseases
The hygiene hypothesis postulates that an environment with a high incidence of infectious diseases protects against allergic and autoimmune diseases, whereas hygienic surroundings increase the incidence of these disorders. This review examines the evidence in support of the hygiene hypothesis and offers a number of mechanisms that could explain the relation between sanitary conditions and susceptibility to allergic and autoimmune diseases. Growing experimental and epidemiologic support for the hygiene hypothesis has important clinical implications, especially with regard to policies on vaccination and the use of antibiotics during childhood.
|
|||||
Clinical Implications of Basic Research: ADAM-33 Surfaces as an Asthma Gene
A recent study identified ADAM-33 as an asthma gene. ADAMs are a subfamily of metalloproteinases, originally identified as proteins on the cell surface, that have two functional domains, a disintegrin and a metalloprotease domain (hence, the acronym ADAM). The authors speculate on the ways in which an excess or deficiency of ADAM-33 could result in the expression of the asthma phenotype.
|
|||||
Sounding Board: Large Employers Seeking New Strategies in Health Care
Large employers are major purchasers of health insurance and have a strong interest in maintaining the health of their employees and containing the costs of care. These efforts focus on giving employees financial incentives and data about quality to encourage them to choose lower-cost and higher-quality care. Several large employers formed a group that compiles and disseminates information about the quality of hospitals, with the goal of steering employees toward higher-quality care.
|
|||||
HOME | SUBSCRIBE | SEARCH | CURRENT ISSUE | PAST ISSUES | COLLECTIONS | PRIVACY | TERMS OF USE | HELP | beta.nejm.org Comments and questions? Please contact us. The New England Journal of Medicine is owned, published, and copyrighted © 2009 Massachusetts Medical Society. All rights reserved. |