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PubMed1996

Transmission of HIV-1 in the breast-feeding process.

Current laboratory techniques cannot distinguish the mode of vertical transmission (intrauterine, intrapartum, or postnatal) of human immunodeficiency virus type 1 (HIV-1) from mother to infant. The ability to transmit HIV-1 via breast feeding has been established in 24 case reports, primarily involving mothers who seroconvert after delivery. Whether breast-feeding adds a notable additional risk of HIV-1 infection to the risk from pregnancy is controversial. The importance of the duration and intensity of breast-feeding in modulating the outcome of HIV transmission via breast milk also remains unclear. Factors in breast milk may play important roles in an infant's susceptibility to infection with HIV and in the expression of the virus. Pasteurization and storage enhance the intrinsic, antiviral properties of human milk. Banked human milk is pasteurized to destroy the HIV-1 virus but retains properties that may be helpful to infants of HIV-1-positive mothers in developed countries where breast-feeding is not recommended. For infants in populations where the infant mortality rate is high, the risk of death associated with HIV infection acquired via breast milk is lower than the risk associated with not being breast-fed.

Acquired Immunodeficiency Syndrome↗

PubMed1998

Senior-age population growth may redefine 'frail elderly'.

Data File: A key to future success in Medicare risk may be how well you manage your frail elderly members who have multiple health problems and chronic conditions. While they may just be a handful of patients in your panel now, data from the U.S. Census Bureau show their numbers are growing.

Aged↗

PubMed1993

Human mobility and malaria risk in the Naya river basin of Colombia.

This paper develops and tests a methodology for examining the manner and the extent to which human mobility can be associated with malaria risk within an endemic area. The paper presents entomological, epidemiological and mobility results obtained from macro data and micro data. Results indicate that malaria is concentrated in the delta zone of the Naya river basin where the circulation of people into this zone for economic reasons occurs at a time when vector densities are high. High human density combined with high vector density ensures continuous and intense transmission of malaria. In attempting to measure intensity of transmission, microscopic analysis of parasitaemia was found to underestimate prevalence showing it to be very low or negligible, whereas serological data collected during the same period of time reveal that prevalence is high, and similar for both sexes. Serological data also indicate that prevalence increases with age particularly from adolescence onwards. Since mobility for agricultural purposes involves able-bodied males and females, there seems ample justification for concluding that human mobility into certain areas increases the risk of infection for adults, particularly when such mobility coincides with peak rainfall and vector densities. Micro-level data are critical in pinpointing causation and small area variations in risk. Thus the beach area is a high risk area within the delta region, particularly for adults, and this is likely to be because of high vector biting rates in the beach environment. One conclusion is that micro analysis of behaviour, when linked to epidemiological data are particularly useful in defining and locating areas and groups at highest risk; using such information to achieve intensive coverage on a small scale may be more cost-effective than attempting to achieve vector or chemotherapeutic control over a wider area for all groups.

Adolescent↗

PubMed2006

Lethal risk to birds from insecticide use in the United States--a spatial and temporal analysis.

We used pesticide use data and previously published models to estimate the lethal risk to birds from insecticides used in U.S. agriculture. Data from the U.S. Department of Agriculture's National Agricultural Statistical Service (NASS, Washington, D.C.) were used to assess how the lethal risk to birds has changed over the period 1991 to 2003 and to compare risk among crop types according to the most recently available surveys. Because the NASS data coverage is incomplete, both with respect to crop and state, we also used a database assembled by the National Center for Food and Agriculture Policy (NCFAP, Washington, D.C.) for the 1997 reference year, to which we added state-specific average application rates for crop/insecticide combinations. For each state/crop/insecticide combination (>6000 entries), we assessed the proportion of crop area on which avian mortality was deemed probable, as well as the extended number of hectares this represented. The crops responsible for most potential bird mortality in the United States were corn and cotton, followed more distantly by alfalfa, wheat, potato, peanut, sugar beet, sorghum, tobacco, and citrus. Other crops represented a higher risk to birds on a per hectare basis. The southeast United States generally had the highest proportion of farmland with a lethal risk to birds. On a positive note, the lethal risk to birds has generally declined over the last decade in most crops, although there are exceptions such as small fruit crops. The reasons for this improvement vary from crop to crop, but usually entail the replacement of older more hazardous products with newer ones with lower acute toxicity to birds.

Animals↗

PubMed2005

Ecological effects of pesticide use in The Netherlands: modeled and observed effects in the field ditch.

This study addresses the potential risks to the aquatic ecosystem posed by pesticides currently used in The Netherlands. The study used a novel method to predict aquatic exposure to pesticides based on a geographic information system (GIS) map of agricultural land use, comprising 51 crops used in open-canopy areas. Through the application of species-sensitivity distributions for aquatic organisms, in combination with rules for mixture-toxicity calculation, the modeled exposure results were transformed to risk estimates for aquatic species. The majority of the predicted risks were caused by pesticides applied to potato cropland, and approximately 95% of the predicted risk was caused by only 7 of the 261 pesticides currently used in The Netherlands. For risk verification, local toxic-risk estimates were compared with observed species composition in field ditches. The field verification study was not able to draw firm conclusions regarding the predicted impact of pesticide use on overall biodiversity. A toxicity-related shift from sensitive to more tolerant or opportunistic species could be observed for a few species.

Agriculture↗

PubMed1991

[Ecological parameters of arbovirus circulation on the north coast of Havana. I. Collection of culicids in the Guajaibon region].

We show the culicids collected in the Guajaibón zone, in Havana Province, in order to characterize the present population according to ecological parameters and the possible risk for man. We show that Aedes scapularis is numerically and ecologically dominant over the rest of the species that attack men, as well as the possible indirect influence of culicid populations in crab caves upon human beings.

Adult↗

PubMed1995

The combined oral contraceptive. Risks and adverse effects in perspective.

The risks and adverse effects of the low dose, new generation progestogen combined oral contraceptives (COCs) are much lower than original studies involving pills containing 50 micrograms estrogen. The main effects are those on the cardiovascular system, lipid and glucose metabolism and cancer. Any effect of the COC on myocardial infarction is probably minimal if the woman has no other risk factors especially smoking. The third generation progestogen, low dose COCs have very little effect on lipid or glucose metabolism. There may be a slight increase in breast cancer if COCs are used under the age of 25 years and for more than 4 to 8 years, and in the risk of cervical cancer. It is too early to estimate long term cancer effects of the newer COCs. Adverse effects such as nausea and breast tenderness can be managed by changing the estrogen dose or the type of progestogen. Overall, the clinical benefits of the COC probably outweight the risks and adverse effects.

Breast Neoplasms↗

PubMed2000

[Epidemiology and therapy of bacterial infections in geriatrics].

As the elderly segment of our population expands, there is an increase of therapeutic problems considering this age group. The elderly patient is generally susceptible to infections because of the decline in host defense mechanisms that occurs with aging, and the underlying chronic diseases of these patients. Increasing numbers of elderly people are being treated in hospitals and are additionally at particular risk of acquiring nosocomial infections with antibiotic-resistant organisms. This article focuses on the epidemiological considerations, risk factors, types of infections that occur in elderly patients, and the guidelines for empiric therapy. The most common infections of the elderly are respiratory tract infection, urinary tract infection, and skin and soft tissue infection. Empirical therapy should be broader in spectrum for elderly patients since the variety of infecting bacteria tends to be greater and the choice of antimicrobial therapy must be based on risk stratification (age, medical illnesses, and severity of presentation). Many additional aspects, e.g., route of administration, drug pharmacokinetics and pharmacodynamics, drug toxicity and drug-drug interactions, compliance, and multiple underlying diseases (e.g., renal failure) must be considered in the rational selection of antibiotic regimen.

Aged↗

PubMed1980

The effect of migration on comparison of disease rates in geographic studies in the United States.

Cancer rates are often compared between counties or other geographic units as a method of testing for risk from environmental exposures. Migration between geographic areas greatly reduces the sensitivity of this method. Under simplifying assumptions the quantitative effect of migration on risk estimates is shown using migration and cancer incidence data for the United States. For example, 40--50% of the relative excess risk, defined as the relative risk minus one, is not reflected in the estimated risk for most cancers, when rates are compared between exposed and unexposed counties and migration has taken place during a 30-year latent period. More extreme losses of sensitivity also occur. Under the simplifying assumptions, the quantitative effect of migration on risk estimates is shown as a function of cancer site, latent period, and the type of geographic units for which rates are calculated--states, counties, or places. Also discussed are some implications of these findings for geographically-based studies and additional data needs for assessing the effect of migration.

Adolescent↗

PubMedDate not supplied

[The effect of maternal education on the risk of infant mortality].

The impact of maternal education on infant mortality in Brazil is analyzed by estimating relative risks in a case control study. "The cases consisted of a sample of infant deaths which were registered at the Registry Office and which occurred in the Metropolitan Region of Porto Alegre (Brazil) in 1980, and the control group was a sample of births occurring in the same region in 1980, and also notified to the Registry Office. With information obtained from a special household survey, a total of 688 cases and 762 controls [were] analyzed...for maternal education and its association with family income, birth order and environmental factors. Specific relative risks (associated with maternal education) have also been calculated separately for 3 groups of cause-of-death and for 3 age-at-death groups." (SUMMARY IN ENG)

Age Factors↗

PubMed1991

Oral contraceptives and coronary heart disease.

In industrialized countries, coronary heart disease (CHD) is a major public health problem for both men and women. Preventive strategies for reducing the excessive mortality and morbidity associated with CHD involve the identification and modification of metabolic factors believed to be involved in the disease process. Three major areas of concern are lipid metabolism, carbohydrate metabolism and the hemostatic system. The steroid hormones contained in oral contraceptives (OCs) have been shown to interfere in all three areas. In many instances OCs have been shown to alter metabolic markers for CHD in directions associated with increased risk. Although evidence is lacking that such changes induce CHD in users of modern, low-dose OCs, it would be prudent to develop formulations with a minimal impact on metabolic risk markers. There is increasing evidence that many of the metabolic disturbances seen in CHD patients share a common origin, and the development of risk-free OCs is likely to require investigation into complex interrelationships.

Blood Coagulation↗

PubMed2004

Environmental and economic factors can increase the risk of exotic species introductions to the Arctic region through increased ballast water discharge.

The effects of global warming can increase the risk of exotic species introductions in eastern Canadian Arctic waters by reducing surface ice cover and allow increased access to commercial vessels. Ballast water discharged by incoming overseas vessels is an important means for introducing species on a global scale. Analyses of air temperatures at Churchill, Manitoba between 1943 and 2002 indicated an increase in mean temperature within the past decade. Churchill is the only major northern port in this region where grain has been exported on a limited basis due to the short navigation season. Economic analyses of grain exported from Canadian and U.S. ports indicated some cost advantages for using northern ports. The Hudson Bay region is vulnerable to increased exotic species introductions because of its southerly location. Current ballast water exchange measures to reduce the risk of introductions may not be effective because most vessels enter the region with ballast, and the ballast exchange zone is located relatively close to coastal areas where the habitat could be favorable for an introduced species to become established. The probability of a large crab species introduced to this region from northern European waters is discussed. The risk of ballast water-related exotic species introduction to this region may be reduced by expanding the types of cargo handled and developing a strong import market. This approach would accommodate an increase in the number of vessels with cargo, and substantially reduce the volume of ballast carried to this region.

Animals↗

PubMed2000

Wall stress distribution on three-dimensionally reconstructed models of human abdominal aortic aneurysm.

PURPOSE: Abdominal aortic aneurysm (AAA) rupture is believed to occur when the mechanical stress acting on the wall exceeds the strength of the wall tissue. Therefore, knowledge of the stress distribution in an intact AAA wall could be useful in assessing its risk of rupture. We developed a methodology to noninvasively estimate the in vivo wall stress distribution for actual AAAs on a patient-to-patient basis. METHODS: Six patients with AAAs and one control patient with a nonaneurysmal aorta were the study subjects. Data from spiral computed tomography scans were used as a means of three-dimensionally reconstructing the in situ geometry of the intact AAAs and the control aorta. We used a nonlinear biomechanical model developed specifically for AAA wall tissue. By means of the finite element method, the stress distribution on the aortic wall of all subjects under systolic blood pressure was determined and studied. RESULTS: In all the AAA cases, the wall stress was complexly distributed, with distinct regions of high and low stress. Peak wall stress among AAA patients varied from 29 N/cm(2) to 45 N/cm(2) and was found on the posterior surface in all cases studied. The wall stress on the nonaneurysmal aorta in the control subject was relatively low and uniformly distributed, with a peak wall stress of 12 N/cm(2). AAA volume, rather than AAA diameter, was shown by means of statistical analysis to be a better indicator of high wall stresses and possibly rupture. CONCLUSION: The approach taken to estimate AAA wall stress distribution is completely noninvasive and does not require any additional involvement or expense by the AAA patient. We believe that this methodology may allow for the evaluation of an individual AAA's rupture risk on a more biophysically sound basis than the widely used 5-cm AAA diameter criterion.

Adult↗

PubMed2006

The use and misuse of biomarkers in ecotoxicology.

Substantial efforts have been devoted to developing and applying biomarkers for use in ecotoxicology. These efforts have resulted partly from a desire for early warning indicators that respond before measurable effects on individuals and populations occur and partly as an aid to identifying the causes of observed population- and community-level effects. Whereas older biomarkers focused on measures of organism physiology or biochemistry, advances in molecular biology are extending the biomarker philosophy to the level of the genes (i.e., ecotoxicogenomics). However, the extent to which biomarkers are able to provide unambiguous and ecologically relevant indicators of exposure to or effects of toxicants remains highly controversial. In the present paper, we briefly discuss the application of biomarkers in ecotoxicology and ecological risk assessment, and we provide examples of how they have been applied. We conclude that although biomarkers can be helpful for gaining insight regarding the mechanisms causing observed effects of chemicals on whole-organism performance and may, in some cases, provide useful indicators of exposure, individual biomarker responses should not be expected to provide useful predictions of relevant ecological effects--and probably not even predictions of whole-organism effects. Suites of biomarkers are only likely to provide increased predictability if they can be used in a comprehensive mechanistic model that integrates them into a measure of fitness. Until this can be achieved, biomarkers may be useful for hypothesis generation in carefully controlled experiments. However, because the aims of environmental monitoring and ecological risk assessment are to detect and/or predict adverse chemical impacts on populations, communities, and ecosystems, we should be focusing our efforts on improving methods to do this directly. This will involve developing and testing models of appropriate complexity that can describe real-world systems at multiple scales.

Animals↗

PubMed2004

[Prevention of dementia (including Alzheimer's disease)].

Prevention of dementia: Life expectancy still increases linearly, and the elderly part of the European population grows rapidly in relation to the young. Dementia, however, grows even more rapidly, because it increases exponentially after age 65; it will become a great burden if nothing is done. The discussion so far is concentrated on treatment, whereas prevention is neglected. The therapy of dementia, however, has limited effect. Contrary to a widespread opinion prevention is possible. Genetic factors alone dominate the fate of cognition only in about 3 % of the cases. Besides age, lifestyle and the vascular risk factors exercise a great influence. High blood pressure carries a fourfold risk, diabetes more than doubles the risk both of the vascular and of the Alzheimer type; combined even more. Especially cerebral microangiopathy is strongly associated with Alzheimer's dementia, it triggers the vicious circle which leads to amyloid deposition. The importance of the circulation is underestimated, because most of the microvascular cerebral lesions are not perceived by the patient. All the risk factors for Alzheimer's disease after age 65 are also vascular risk factors especially for microangiopathy: Apo-E4, oestrogen deficiency, insulin resistance, diabetes, arterial hypertension, high cholesterol, old age and increased plasma homocystin which is often caused by alcohol consumption even in moderate doses. A healthy life style with daily outdoor activity and a Mediterranean diet not only reduces the risk of dementia, but also of coronary death and cancer. Cognitively stimulating activity protects even more than physical activity against dementia; the basis for this is acquired in youth by education. Therapy with statins is advisable if atherosclerosis cannot be reasonably counteracted by physical activity and diet.

Aged↗

PubMed2001

Response of phytoplankton communities to liquid creosote in freshwater microcosms.

We assessed the response of phytoplankton communities in aquatic microcosms to single applications of liquid creosote. The creosote was applied to 14 microcosms at concentrations ranging from 0.06 to 109 mg/L. Two microcosms served as controls. Phytoplankton samples were collected from each microcosm one week and 1 d before treatment and at 7 and 21 d after treatment. Temporal changes (response-recovery) in phytoplankton community composition were assessed with principal response curves. Creosote had no direct toxic effect on the phytoplankton community based on total abundance and number of taxa. Population levels declined in all treatments between day -1 and day 7, but this trend mirrored a similar decline in the control microcosms. At both 7 and 21 d after treatment, population densities and number of taxa in most treatments exceeded those in the controls and exhibited a parabolic relationship relative to creosote concentration. This relationship was most pronounced at 21 d, at which time population densities and number of taxa at intermediate concentrations were up to twice those at low and high concentrations. This response pattern seems to represent an indirect response to impacts on zooplankton and a corresponding reduction in grazing pressure. In contrast, total algal biomass declined 52 to 97% relative to the controls at all but the lowest creosote concentration at 7 d. This apparent decline was due to a significant proliferation of the alga Closterium moniliforme in the controls and low creosote concentration. At 21 d, no difference was found in total biomass between treated and control microcosms. The results of this study suggest that creosote does not pose a significant direct risk to phytoplankton at concentrations likely to be encountered in most contaminated aquatic environments; however, stimulation of algal populations could occur in situations of long-term chronic exposure or spill events that remove predatory zooplankton populations.

Animals↗

PubMed1999

The potential effect on hip fracture incidence of mass screening for osteoporosis.

With ageing of the Australian population, treatment of osteoporosis-related hip fractures will impose an increasing burden on the healthcare system. Based on current age-adjusted hip fracture incidence and population projections for New South Wales, we estimated a 90% increase in hip fractures by the year 2021. Contributing significantly to this increase will be the number of men reaching the high risk age group for osteoporotic hip fractures. A suggested solution--screening and appropriate therapy for individuals at high risk of osteoporosis--may have only a modest impact. Our calculations show that, even with optimistic screening and therapy compliance rates, hip fractures could still increase by over 50%. Other approaches need to be further explored.

Aged↗

PubMed2003

Assessing the impact of the Japanese 2005 World Exposition Project on vascular plants' risk of extinction.

The Red Data Book of Japanese Vascular Plants is based on their risk of extinction. In order to construct the list, 2000 taxa were evaluated using population data and rates of decline for approximately 4400 grids, each of approximately 100 km(2). This database can be used to estimate the impact of human activity on a threatened plant's risk of extinction. In order to evaluate extinction risks and apply the evaluation to conservation actions, the discount mean time to extinction is defined as a measure of extinction risk, where the present value of a species' persistence in the future decreases exponentially. The rate of decrease has to be much less than the rate of economic discounting, in order to realize intergenerational sustainability. Increases of the inverse, and logarithm, of the discount mean time to extinction are considered measures of the extinction risk. We applied these measures to an environmental impact assessment for the Japanese World Exposition that is to be held in 2005. Development will have a greater impact on threatened Salvia species than it will on star magnolia, Magnolia tomentosa, which has been conserved by changing the site plan.

Conservation of Natural Resources↗