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At least 1,315 records · Page 73Linked to original sources
PubMed2000

Carbon tetrachloride is immunosuppressive and decreases host resistance to Listeria monocytogenes and Streptococcus pneumoniae in female B6C3F1 mice.

Carbon tetrachloride (CCl(4)) is an environmental contaminant that has been detected in ambient air, seawater, surface-water and snow. The immunotoxic potential of CCl(4) was evaluated in female B6C3F1 mice. The animals were administered with CCl(4) daily for 14 days at doses of 50, 100, 500 or 1000 mg/kg body weight by gavage with corn oil as a vehicle. Exposure to CCl(4) resulted in an increase of liver weight but not the body weight and the weights of brain, spleen, lungs, thymus and kidneys. Exposure to CCl(4) produced minimal effect on differential hematological parameters; however, it produced a significant increase in serum glutamic-pyruvic transaminase (SGPT) levels in all dose groups while other serum chemistries showed sporadic increases, primarily at the dose level of 1000 mg/kg. Exposure to CCl(4) produced a decreased humoral immune response; the IgM antibody forming cell (AFC) response to sheep red blood cells (sRBC) was suppressed with the maximal decrease (45%) observed at the dose level of 1000 mg/kg. The IgM serum titer to sRBC was also reduced with a maximal decrease (54%) observed at the dose level of 500 mg/kg. Although exposure to CCl(4) had no effects on the mixed leukocyte response (MLR), cytotoxic T lymphocyte activity and natural killer (NK) cell activity, a decrease in both the absolute number and the percentage of CD4(+)CD8(-) at the dose level of 500 mg/kg was observed. The functional activity of the mononuclear phagocyte system was compromised as reflected by a decrease in the vascular clearance of (51)Cr-sRBC and a decrease in the uptake of (51)Cr-sRBC by the liver. Finally, in the two host resistance models evaluated, exposure to CCl(4) decreased host resistance to both Streptococcus pneumoniae and Listeria monocytogenes with greater susceptibility to the latter. Overall, these studies demonstrate that CCl(4) was immunosuppressive in female B6C3F1 mice.

Alanine Transaminase↗
PubMed1986

Cataract and retinopathy: screening for treatable retinopathy.

Diabetes causes cataract and certain physical changes in the lens. The diabetic lens is larger than the non-diabetic and shows greater light scatter and fluorescence. Both hyperglycaemia and lowering of blood glucose case refractive changes and hypermetropia is the most common. Classical 'snow-flake' juvenile cataract associated with hyperglycaemia is now rare. It has an osmotic mechanism. Diabetes is a risk factor for cataract in adults which is duration dependent, more frequent in women and leads to earlier surgery. It resembles non-diabetic senile cataract. Extracapsular cataract extraction is the method of choice for diabetic cataract with a better visual result and less risk of rubeosis iridis. A posterior chamber implant may still permit retinal photocoagulation if necessary. Diabetic retinopathy is still the leading cause of blindness in the working age group. The beneficial effect of photocoagulation has been shown by randomized controlled trials to be long-lasting for both proliferative retinopathy and maculopathy. Therefore there is a need for screening, especially for those with proliferative disease which may be present without symptoms. A knowledge of risk factors will enhance detection rate with duration as the strongest determinant for retinopathy. Any screening modality should be highly sensitive as well as specific. The role of different professionals as potential screeners should be considered. Adequate provisions include facilities for checking vision and for dimming ambient lighting. Mydriasis and a good ophthalmoscope light will increase detection rate. The use of a 45 degrees non-mydriatic camera is unlikely to supplant the use of an ophthalmoscope as a single field is likely to miss important lesions. A 60 degrees camera may confer a large enough field and the use of transparencies will provide magnification when films are projected but the camera is more difficult to use. A list of features chosen by a recent study to characterize sight-threatening retinopathy is included and their presence indicates the need for referral to an ophthalmic clinic for treatment or close observation.

Adolescent↗
PubMed2003

Silvicultural management in maintaining biodiversity and resistance of forests in Europe-temperate zone.

In Europe temperate forests play a prominent role in timber production, nature protection, water conservation, erosion control and recreation. For centuries temperate forests in Europe have been affected by forest devastation and soil degradation. Applying great efforts to eliminate the severe wood shortage of those days, countermeasures were taken during the last 150 years by regenerating and tending highly productive forests. High growth rates and an increasing growing stock of these forests indicate that formerly stated goals have been successfully achieved. Coniferous species were often favoured because they were easy to establish and manage, and gave reason for high volume growth expectations. Today coniferous forests expand far beyond the limits of their natural ranges. These changes have been accompanied by a loss of biodiversity, a shift to nonsite adapted tree species and reduce the resistance against storms, snow, ice, droughts, insects and fungi. Some of these hazards were further intensified by the increasing average stand age, as well as in some areas by severe air pollution. Climatic fluctuations, especially changes in the frequency and intensity of extreme warm and dry climatic conditions and of heavy storms, had considerable impact on forest ecosystems. The changing demands of today require a widened scope of forest management. Society is asking for sustainable forestry emphasizing biodiversity and naturalistic forest management. It is of great economic and ecological relevance to know on which sites today's forests are most susceptible to climatic and other environmental changes and hazards. In those areas adjustments of management through a conversion the prevailing forests towards more site adapted mixed forests needs to be considered with priority. The high diversity in site conditions, ownership, economic and socio-cultural conditions require strategies adapted to the local and regional needs. Higher resistance of forests will increase economic and social benefits of forests and reduce the risks by maintaining sustainable forestry.

Climate↗
PubMed1999

Parasites, biodiversity, and population dynamics in an ecosystem in the high arctic.

The abomasa of 163 Svalbard reindeers (Rangifer tarandus platyrhynchus) from Nordenskiöld Land, Spitsbergen (78 degrees N, 15 degrees E) were examined for adult and juvenile nematodes. Spitsbergen has midnight sun from late April to late August, arctic night from late October to mid-February, permafrost, and snow cover from October to June. Plant growth is restricted to 6-8 weeks, usually starting mid-June. In the reindeer calves, which are born in June prevalence and intensity of infection increased over the winter. All young (1 year) and adult (older than 1 year) reindeers were infected. Variations in worm burden, fraction of adult nematodes, male to female ratio in the nematodes, number of adult nematodes, number of juvenile nematodes, and distribution of juvenile nematodes on length groups were analysed for relationships with sex and age of host, and time of the year. The material was further analysed for relationships between the reindeer's content of stored fat and worm burden and its elements. It is concluded that transmission of nematodes to the reindeer continues over the winter and that arrested larval development has not been strongly selected for in this High Arctic locality. Infection continued to increase in adult males but not in adult females with age. This is explained as a balance between gain and loss of worms in the females connected to levelling off of food intake at end of somatic growth. In adult male reindeers there was a negative trend between stored fat and infection at all seasons. In reproducing females there were significant negative relationships in winter-spring, while in yeld females no significant relationship was found. The nematodes belonged to the following taxa: Ostertagia gruehneri m. gruehneri, O. gruehneri m. arcticus, Marshallagia marshalli m. marshalli, M. marshalli. m. occidentalis, Teladorsagia circumcincta m. circumcincta, T. circumcincta. m. trifurcata, and T. circumcincta. m. davtiani. There appears not to be any specially adapted species among the helminth parasites of reindeer (Rangifer tarandus) and muskoxen (Ovibos moschatus) in the High Arctic. In the Low Arctic Uminmakstrongylus pallikuukensis of muskoxen may be an example of such adaptation.

Abomasum↗
PubMed1980

The Moberg volar advancement flap for digital reconstruction.

The volar advancement flap described by Moberg in 1964 has been used to restore normal sensation to soft tissue deficits of the thumb. Application of this same technique for finger tip injuries was later suggested by Snow, but differences in digital blood supply led to dorsal tip necrosis and selection of other reconstructive techniques by many surgeons. Other methods have the disadvantages of widened two-point discrimination, a tender pulp scar, or an unacceptable donor site. The volar advancement flap applied to fingers restores normal to nearly normal sensation, an adequate pulp with minimal deformity. Our experience with the volar advancement flap in 69 digits from 1969 to 1978 is reviewed. Preservation of the dorsal perforating vessels is most important in successfully executing this procedure. No dorsal tip or flap necrosis occurred. Two-point discrimination was normal or within 2 mm of contralateral values in every digit. Full range of motion, or less than 5 degrees extension loss, was recorded in all fingers that were normal prior to operation. Our results suggest this to be a safe as well as effective adjunct in the treatment of finger tip injuries.

Adolescent↗
PubMed2001

The paradox of great longevity in a short-lived tree species.

Thuja occidentalis is a tree species that was once thought to be relatively short-lived (80 years). Up until 10 years ago maximum ages were considered to be near 400 years, but such trees were thought to be rare. Research along the cliffs of the Niagara Escarpment has altered this view. Exceptionally slow-growing trees of this species have been found with ring counts to 1653 years and estimated ages to 1890 years. Senescence is slow or absent. Injury and death is due to rockfall and sporadic severe drought that kills small sectors of the trees by exposing and killing the roots. Experiments in which colored dyes are infused into roots show that each tree is composed of hydraulically independent units that allow mortality in one part of the 'individual' with little negative effect on the remaining parts of the tree. The trees are small, so environmental loadings of ice, snow, and wind are low. Slow growth of the trees results in a much greater mechanical strength in the wood. Together these properties increase the ability of the cedars to persist on cliffs for long periods of time. The paradox of great longevity in this 'short-lived' tree species is explained by slow growth that minimizes maintenance and repair costs while maximizing durability and strength, combined with an internal architecture that creates functionally independent units within each tree.

Aging↗
PubMed1998

Fractures and other injuries from falls after an ice storm.

This is a retrospective review of all patients seen at an urban emergency department for 9 days after an ice storm because of a fall on ice. Date of presentation, age, sex, and anatomic location and type of injury were tabulated. Risk factors for fractures were identified. A total of 327 injuries were identified in 259 patients. Back injury was most common (19.3%). Ninety-one patients sustained 93 fractures. Ankle fractures were most common (24.7%), followed by fractures of wrist (19.4%) and hip (14.0%). Ankle fractures were more common than other studies of falls after a snow storm. Fracture was significantly related to age (P = .0001). There was a trend for women to sustain fractures (P = .07). Unlike other mass casualty events, fractures and injuries peaked on the 5th and 6th day after the storm, allowing adequate time for mobilizing resources to care for the injured.

Accidental Falls↗
PubMed1997

Season and migration alters the corticosterone response to capture and handling in an Arctic migrant, the white-crowned sparrow (Zonotrichia leucophrys gambelii).

The Gambel's race of white-crowned sparrow (Zonotrichia leucophrys gambelii) migrates each year from their wintering grounds in the Southwestern United States to the Arctic to breed. Associated with this migration is a change in both the nonstressed and the stress-induced levels of circulating plasma corticosterone. Birds were captured at two sites on their wintering grounds (New Mexico and Arizona). Although stress-induced corticosterone levels were elevated at each site compared to nonstressed levels, there were no differences between wintering sites. These were also similar to levels in birds caught in Washington state during fall migration. In contrast, nonstressed corticosterone values were greatly elevated in birds on their breeding grounds in Alaska and similar to stress-induced levels in wintering birds. Corticosterone levels rose even further in response to the stress of capture and handling in breeding birds. These augmented corticosterone levels during breeding were not associated with weather. Both nonstressed and stress-induced corticosterone levels were similar in birds caught on their breeding grounds on two different years, one with temperatures during mid-May of approximately 0 degree C during a snow storm and the other with temperatures in the mid-20s. These results suggest that seasonal physiological changes, and not local conditions, underlie seasonal changes in corticosterone levels. Furthermore, birds caught in Washington state during spring migration had intermediate levels of both nonstressed and stress-induced corticosterone. Corticosterone release may function differently during spring and fall migrations.

Adipose Tissue↗
PubMed1999

P.A. Schleisner: a pioneer in epidemiology.

In 1847 Schleisner (b. 1818) was sent from Copenhagen to the Vestmanna Islands in Iceland to study the epidemic of tetanus neonatorum. The neonatal mortality in those islands at that time was 600-740 per 1000 children. He built a small hospital and introduced treatment with Peru balsam of the umbilicus. Schleisner probably assumed that the infection was caused by airborne infection, contact infection or poor hygiene. The neonatal mortality fell to about 50 per 1000. Schleisner published his results in 1849. Semmelweiss published his observations in 1850 and Snow successfully fought the cholera epidemic in London in 1854. Schleisner deserves recognition as a pioneer in the field of epidemiology.

Epidemiology↗
PubMed1996

Two cases of severe postpartum anaemia in Jehovah's witnesses.

Two cases of severe postpartum anaemia are presented in Jehovah's witnesses who refused blood transfusion. Despite haemoglobin concentrations of less than 3 g/dl both women survived. General management was directed to maximizing oxygen delivery and minimizing oxygen consumption. The use of an emulsified perfluorocarbon was organized for one of the cases, but was not administered because a snow storm prevented its delivery to the hospital. In the other case, recombinant human erythropoietin was used to encourage red cell production. The recovery of haemoglobin concentration in the two cases is compared.

Journal Article↗
PubMed2000

Oxidation-state distribution of plutonium in surface and subsurface waters at Thule, northwest Greenland.

The speciation of plutonium in Arctic waters sampled on the northwest Greenland shelf in August 1997 is discussed in this paper. Specifically, we report the results of analyses carried out on seawater sampled (a) close to the Thule air base where, in 1968, a US military aircraft carrying four nuclear weapons crashed on sea ice, releasing kilogram quantities of plutonium to the snow pack and underlying seabed sediments, and (b) at a reference station (Upernavik) located approximately 400 km to the south. The data show that most of the plutonium in the dissolved phase at Thule is in the form of Pu(V, VI) (mean: 68+/-6%; n = 6), with little if any distinction apparent between surface and bottom waters. Further, the oxidation state distribution at stations close to the accident site is similar to that measured at Upernavik, remote from this site. It is also similar to the distribution observed in shelf waters at mid-latitudes, suggesting that the underlying processes controlling plutonium speciation are insensitive to temperature over the range 0-25 degrees C. Measurements using tangential-flow ultrafiltration indicate that virtually all of the plutonium (including the fraction in a reduced chemical form) is present as fully dissolved species. Most of this plutonium would seem to be of weapons fallout origin, as the mean 238Pu/239,240Pu activity ratio in the water column (dissolved phase) at Thule (0.06+/-0.02; n = 10) is similar to the global fallout ratio at this latitude (approximately 0.04). Thus, there is little evidence of weapons-grade plutonium in the water column at Thule at the present time.

Aircraft↗
PubMed2000

Empowering communities to remove the pump handle. An emerging role in epidemiology.

PURPOSE: The epidemiologist's role in relation to the populations they study needs to be reconsidered in order to maximize the contribution of epidemiology to public health, and to balance science with social responsibility.METHODS: Historical analysis and a case study of community-based, collaborative epidemiology conducted in Eastern Virginia as the basis for identifying and improving child health outcomes.RESULTS: The origins of epidemiology in Snow's work on cholera provides a dynamic model of etiologic research combined with community intervention to prevent disease. While in past decades, epidemiology was excessively objectivist and focused on identifying individual-level risk factors, epidemiologists are now reclaiming a vital role in community health promotion. Yet the historic role of the epidemiologist, whether as the white knight who saves the community from an epidemic, or alternatively, as the remote scientist who studies populations but bears no responsibility for improving their health, is no longer viable. The emerging role is that of collaborator, a scientist working in partnership with communities. In Eastern Virginia, academic epidemiologists work closely with diverse community-based coalitions to assess child health needs, prioritize health problems, design and enact interventions, and monitor health outcomes. Diagnostic studies of child health outcomes, published in peer-reviewed journals and in community reports, have identified serious health needs in Eastern Virginia, e.g., under-immunization, attention deficit hyperactivity disorder, asthma, and adverse perinatal health indicators. Epidemiologic research is being used to guide interventions planned and enacted by the community, with evidence of improved outcomes in certain indicators.CONCLUSIONS: A vitally important, emerging role for epidemiologists in the 21(st) century is to empower communities to identify and effectively address their own health needs. Epidemiologic data not only evaluates health status, but should be used to guide community action.

Journal Article↗
PubMed2002

Role of Eloesser flap and thoracoplasty in the third millennium.

In the modern era of thoracic surgery, few indications remain for thoracoplasty. Indeed, many surgeons believe that the resulting deformity outweighs the usefulness of collapse therapy. Rather than trying to obliterate chronic spaces, these surgeons advocate myoplasty techniques to fill the space. Unfortunately, these techniques are not minor procedures and two to three operations are often necessary to solve the problem. This is the reason why thoracoplasty remains the best option in selected patients. In some cases, it should be a first-line procedure rather than as a last resort when everything else has failed. In their discussion of the article by Horrigan and Snow [31], Pairolero and Trastek [44] summarized well the current attitudes toward these different concepts: "Although management of the chronically infected pleural space has changed over the years, the goals of therapy remain the same to conserve the patient's life with a healed chest wall without evidence of infection. Determination of which techniques are necessary to achieve these goals must be tailored to the individual patients."

Bandages↗
PubMed2003

Does making clinic-based reproductive health services more youth-friendly increase service use by adolescents? Evidence from Lusaka, Zambia.

PURPOSE: To report the findings of a study that evaluated the impact of three youth-friendly service (YFS) projects in Lusaka, Zambia. In 1994, the Lusaka District Health Management Team (LDHMT) identified adolescents as a priority underserved population with regard to reproductive health information and services. As part of its long-term goal to improve the health and well-being of Lusaka youth, the LDHMT, in collaboration with CARE, UNICEF/Zambia Family Life Movement, and John Snow International, implemented three separate YFS projects to increase service use among adolescents. METHODS: Service statistics from 10 clinics (8 "treatment clinics" and 2 "non-YFS clinics") were used to measure adolescent service use. Qualitative and quantitative data were collected to measure the degree of "youth-friendliness" at the clinics and the level of community acceptance of providing reproductive health services to youth. Specific indicators of youth-friendliness were developed that measured the attitudes of the clinic staff toward giving services to youth, whether clinic staff honored privacy and confidentiality, whether boys and young men were welcomed, whether the clinic policies supported providing services for youth, whether clinic staff promoted its services to youth in surrounding community, and whether youth, themselves, perceived that they would be welcomed and have their needs met at the clinics. Similarly, indicators of community acceptance were developed that measured whether parents and other adults supported the provision of reproductive health services to youth. RESULTS AND CONCLUSIONS: Although the projects appear to have improved the clinic experience for adolescent clients and to have increased service use levels at some clinics, the findings suggest that community acceptance of reproductive health services for youth may have a larger impact on the health-seeking behaviors of adolescents.

Adolescent↗
PubMed1997

The cannabinoid receptor: computer-aided molecular modeling and docking of ligand.

A three-dimensional model of human cannabinoid receptor is constructed using computer-aided molecular modeling techniques. The helices of bacteriorhodopsin were used as the initial template to construct the transmembrane helices. The extracellular and intracellular loops were added using the SYBYL molecular modeling package. The extracellular N terminus was modeled on the basis of its similarity to rat oncomodulin. Similarly, the C terminus was constructed on the basis of similarity to bovine prothrombin fragment 1. The final structure was refined by several runs of minimization and dynamics calculation using the CHARMm package. delta 9-Tetra hydrocannabinol was docked into the internal cavity using the AUTODOCK program. Our study snows that there may be a calcium-binding site in the extracellular N terminus of this receptor. The ligand binds mainly to a hydrophobic site, which consists of residues Met-240, Trp-241 (TMH-4), Trp-356, Leu-359, Leu-360 (TMH-6), and Ala-283 (TMH-5). Its phenolic hydroxyl group forms a hydrogen bond with the carboxy group of Ala-198 (TMH-3). The results of modeling agree well with experimental QSAR studies.

Amino Acid Sequence↗
PubMed2002

Arctic spring: hormone-behavior interactions in a severe environment.

Arctic breeding birds arrive on their nesting grounds in spring when weather conditions may still be extreme (low temperature, snow). The brief Arctic summer requires that they begin breeding as early as possible to take advantage of the ephemeral abundance of food to feed young. Failure to adjust to the local phenology results in drastically reduced reproductive success. Hormone-behavior adaptations may have evolved that maximize survival and reproductive success in the Arctic. It has been shown that the interrelationship of testosterone and territorial aggression, as birds arrive on the Arctic breeding grounds, varies according to species and locality. In some, territoriality is extremely brief following which birds become apparently refractory to the effects of testosterone. Others are territorial throughout the breeding season, but the dependence of these behaviors upon activation by testosterone is lost. Extensive data also indicate that Arctic birds modulate the adrenocortical response to acute stress. Secretion of corticosterone in response to a standardized capture stress protocol, used to mimic acute stress as a function of local environmental conditions, varies with the stage in the breeding cycle. Arctic breeding birds modulate the sensitivity of the adrenocortical response to acute stress at both the population and individual levels. These modulations are thought to be adaptations to allow the onset of territorial behavior and breeding in the face of potentially stressful conditions. Behavioral and physiological responses to corticosterone treatment are also diminished. A combination of these two hormone-behavior interrelationships can form important components of the proximate mechanisms by which birds, and other vertebrates, breed successfully in a severe and often capricious environment.

Adrenocorticotropic Hormone↗
PubMed1997

Ostertagia nianqingtanggulaensis Kúng & Li, 1965 (Nematoda: Trichostrongyloidea) from sheep and goats at high altitudes in Nepal.

The trichostrongyloid nematode Ostertagia nianqingtanggulaensis Kúng & Li, 1965, previously recorded only from sheep in Tibet, is redescribed and is shown to be a common parasite of both sheep and goats at higher altitudes in the Himalayan foothills of western Nepal. Herbage examination indicated that infective larvae can overwinter on snow covered slopes. Use of tracer animals confirmed that migratory flocks are exposed to infection when grazing on alpine pastures during the summer months. In contrast, nearby non-migratory flocks kept at lower altitudes did not harbour O. nianqingtanggulaensis and tracer animals grazed with these flocks did not become infected with this species.

Altitude↗
PubMed1973

California encephalitis virus endemicity in the Yukon Territory, 1972.

Sera from 218 of 1574 (14%) small mammals collected in the Yukon Territory between 14 May and 13 August 1972 neutralized a Yukon strain of California encephalitis virus (snowshoe-hare subtype). These included 133 of 319 (42%) snowshoe hares (Lepus americanus), 84 of 1243 (7%) ground squirrels (Citellus undulatus) and 1 of 12 (8%) tree squirrels (Tamiasciurus hudsonicus). California encephalitis virus (snow-shoe hare subtype) was isolated from four pools of unengorged Aedes communis mosquitoes collected near Whitehorse (61 degrees N., 135 degrees W.) and on one occasion each from pools of the same species collected at Hunker Creek (64 degrees N., 138 degrees W.) and at mile 125, Dempster Highway (66 degrees N., 138 degrees W.) during July 1972. Replication of a Yukon strain of California encephalitis virus was observed in wild-caught Culiseta inornata and Aedes canadensis mosquitoes after intrathoracic injection and holding at temperatures of 80 degrees , 50 degrees and 40 degrees F.

Animals↗