Malaria in Nonimmune Travelers

Background: With the current increase of international travel to tropical endemic areas, the incidence of malaria being imported into nonendemic countries has increased significantly. Disagreement concerning malaria chemoprophylaxis and inadequate knowledge of malarious areas, morbidity, and pretravel advise has led to confusion among both health professionals as well as travelers. Therefore, this study was conducted to investigate malaria imported into Germany by identifying the high-risk endemic areas, clinical presentations, and chemoprophylactic and therapeutic regimens related to reported cases. Methods: Between 1990 and 1993, the 160 nonimmune travelers, all German nationals or residents for more than 10 years, presenting to our travel clinic with microscopically confirmed malaria were investigated. For each, the travel history, chemoprophylaxis used during travel, symptoms, pathological diagnosis, and treatment efficacy were analyzed. Results: Africa (73%), Asia (21%), and Central South America (6%) were the endemic countries visited by our patients, of whom only 3% used the chemoprophylaxis recommended for their destination. Plasmodium falciparum was the most common pathogen, found in more than half of our patients, and P. vivax (29%), P. ova le (6%), P. malariae(6%), a mixed infection with P.falciparum and P vivax (3%) were also detected. All patients presented with fever and headaches, a majority with profuse night sweats, insomnia, arthralgias, and myalgias, and diarrhea and abdominal cramps were experienced in 13% and 8%, respectively. In falciparum malaria, a recrudescence was observed in all patients who received chloroquine only, whereas quinine, halofantrine, and mefloquine were highly effective. In vivax malaria, a relapse rate of 14% was noted in the patients treated with the currently recommended regimen of chloroquine and primaquine. Conclusions: Visitors to endemic countries, especially to Africa, are of significant risk. Given the low compliance rate of chemoprophylaxis, a high percentage of malaria in our patients could have been avoided by an appropriate prophylaxis regimen and optimal pretravel counseling

Cutaneos larva migrans in travelers

The symptoms, medical history, and treatment of 98 patients with cutaneous larva migrans (creeping eruption) who attended a travel-related-disease clinic during a period of 4 years are reviewed. This condition is caused by skin-penetrating larvae of nematodes, mainly of the hookworm Ancylostoma braziliense and other nematodes of the family Ancylostomidae. Despite the ubiquitous distribution of these nematodes, in the investigated group only travelers to tropical and subtropical countries were affected; 28.9% of the patients had symptoms for > 1 month, and for 24.5% the probable incubation period was > 2 weeks. The efflorescences typically were on the lower extremities (73.4% of all locations). The buttocks and anogenital region were affected in 12.6% of all locations, and the trunk and upper extremities each were affected in 7.1%. Only a minority of patients presented with eosinophilia or an elevated serum level of IgE. No other laboratory data appeared to be related to the disease. Therapy with topical thiabendazole was successful for 98% of the patients. Systemic antihelmintic therapy was necessary in two cases because of disseminated, extensive infection

Low Temperature Synthesis and Characterization of Nesquehonite

Nesquehonite, Mg(HCO3)(OH).2H2O or MgCO3.3H2O, was named after its type locality in Nesquehoning, Pennsylvania, USA. The structure of nesquehonite can be envisaged as infinite chains of corner sharing MgO6 octahedra along the b-axis. Within these chains CO32- groups link 3 MgO6 octahedra by two common corners and one edge. This structural arrangement causes strong distortion of the octahedra. Chains are interconnected by hydrogen bonds only, whereby each Mg atom is coordinated to two water ligands and one free water molecule is located in between the chains [1, 2]. Under natural conditions nesquehonite can form in evaporites depending on the availability of Mg2+ ions in solution relative to other cations, such as Ca2+ [3-5]. Additionally, nesquehonite occurs as an alteration product in the form of scales or efflorescences on existing carbonate rocks, serpentine, or volcanic breccias [6-11]. Interestingly it has also been observed on the surface of a limited number of meteorites found in Antarctic regions, where it has formed by reactions of the meteorite minerals with terrestrial water and CO2 at near freezing temperatures [12-16]. Nesquehonite has also been identified on the surfaces of manmade materials, such as bricks and mortar [17, 18]. The synthesis of nesquehonite forms a continuation of our work on the synthesis and study of the vibrational spectroscopy of natural and synthetic minerals in the hydroxide (brucite, gibbsite, boehmite, etc.)[19-23], carbonate (cerussite, azurite, malachite, etc.)[24-26] and hydroxycarbonate (hydrotalcite)[21, 27-32] groups. This work aims at describing a simple method for the synthesis of nesquehonite and the detailed characterization of the structure and morphology by X-ray diffraction (XRD), vibrational spectroscopy and scanning electron microscopy (SEM)

Latency effects in orientation popout

AbstractA target that differs in orientation from neighboring lines and “pops out” has been found to evoke larger responses in cortical V1 cells than lines in the uniform texture surround which do not popout (e.g., Journal of Neurophysiology 67 (1992) 961). If this is more than a coincidence of observations, physiological properties of contextual modulation should be reflected in the perception of salience. In particular, as the differential suppression from texture surround has been reported to be delayed, target salience may be affected by the history of surrounding lines, i.e. by their orientation before the target was presented. This was tested using a feature flicker paradigm in which target and background lines changed their orientations (Experiment 2). All subjects (N=4) indicated a benefit in target detection when target orientation was not previously present in the surround. A control experiment showed that this effect was not caused by the purely temporal aspects of asynchronous stimulus presentation (Experiment 3). To distinguish this effect from other sources of delayed processing, Experiment 1 compared the performance in target detection and target identification tasks, for single-lines and popout targets. All subjects required longer stimulus presentation time to identify the orientation of a single line than to detect the line itself, indicating that orientation coding needs longer processing than encoding stimulus onset. However, most subjects needed even longer presentations to detect popout, suggesting that the processing of orientation contrast adds to this delay. In an appendix, putative response variations of V1 cells to asynchronous flicker are computed

Microstructure and early diagenesis of recent reef building scleractinian corals, Heron reef, Great Barrier Reef : implications for paleoclimate analysis

Scleractinian corals increasingly are studied as geochemical archives of modern- and palaeoclimate, but microsampling for geochemical data is complicated by: 1) the microstructural complexity and spatial variability in skeletal growth in different coral genera; and 2) the rapidity and scale of diagenetic alteration that occurs in living coralla. Geochemical sampling techniques now have spatial resolution into the sub-micrometer to tens of micrometers range, and it is hoped that the spatial resolution can be translated to temporal resolution. This study investigated the effects on geochemical analyses imposed by microstructure and diagenesis in different live-collected coral genera representing somewhat different depositional environments. Suites of samples of four reef-building genera (Acropora, Pocillopora, Goniastrea and Porites) were collected from three adjacent environments in intertidal and subtidal positions near the reef edge at Heron Reef, Great Barrier Reef and studied by means of optical and scanning electron microscopy, combined with vibrational and energy dispersive spectroscopy. The first section of this study compares and documents the microstructure of the four coral genera. Each genus was found to have very different three-dimensional arrangements of microstructural elements, and a new general growth model was proposed for Acropora, to take into account differences in the timing of precipitation of trabeculae and thickening deposits. The results highlight the complexity and spatial variability of skeletal growth in different coral genera. Because microstructural patterns vary in different genera, direct observation of microstructural elements and growth lines are necessary to allow geochemical microsamples to be placed into series that represent temporal sequences with known degrees of time averaging. Coral growth rates (i.e., rates of extension) are discussed to determine the range of temporal relationships that exist between closely spaced skeletal microstructural elements. Such data are necessary in order for coral skeletogenesis to be understood and are critical for constraining microsampling strategies aimed at developing true time series geochemical data at very fine spatial and temporal scales. The second part of the study focused on early diagenetic alteration of the corals, which is an equally important concern for geochemical analysis. Early marine diagenesis was documented in the same live-collected samples of the four common reef-building coral genera. Samples show extensive early marine diagenesis where parts of the coralla less than three years old contain abundant macro- and microborings (sponges, algae, cyanobacteria and fungi) and significant amounts of aragonite, high-Mg calcite, low-Mg calcite and brucite [Mg(OH)2] cements. Many of the cements are associated with microendoliths and endobionts that inhabit recently abandoned parts of the skeleton. The cements are problematic for palaeoclimate reconstruction because geochemical proxies used for paleoclimate studies are meant to reflect ambient seawater chemistry and conditions, but the occurrence of brucite and low-Mg calcite demonstrates how far fluid chemistry in microenvironments within the corals has evolved from ambient seawater. Some Porites lobata specimens have had as much as 60% of the most recently deposited skeletal aragonite (i.e., the part of the skeleton that projects into the layer of living polyps) bored and replaced by low-Mg calcite cement. The low-Mg calcite cement has significantly different trace element ratios (Sr/Ca(mmol/mol) = 6.3 ± 1.4; Mg/Ca(mmol/mol) = 12.0 ± 5.1) than the host coral skeletal aragonite (Sr/Ca(mmol/mol) = 9.9 ± 1.3; Mg/Ca(mmol/mol) = 4.5 ± 2.3), thus providing a serious challenge for Sr/Ca or Mg/Ca based sea surface temperature calculations. This study illustrates that many diagenetic changes that can radically alter important geochemical characteristics of coral skeleton occur very early on the sea floor (i.e., while corals are still alive). Documented cements altered trace element inventories (e.g., Sr and Mg), thus, interfering with the use of those elements in palaeotemperature calculations. Hence, significant diagenetic changes that jeopardise palaeoclimate data do not require long-term diagenesis or meteoric exposure. Some of the diagenetic changes (e.g., calcite filled borings) occur at scales that are very difficult to detect short of visual inspection using SEM. Hence, vetting of coral samples with SEM is required before any sample is subjected to geochemical analysis

Kilocycle range dislocation damping in dilute magnesium alloy single crystals

The kilocycle range dislocation damping and Young\u27s modulus of single crystals of magnesium and single crystals of magnesium containing small additions of lithium, zinc, or aluminum have been studied as a function of strain amplitude, temperature, and time during annealing and following a high strain amplitude vibration. The data are compared to the Granato-Lücke theory of dislocation damping, the Granato-Hikata-Lücke theory for the recovery of damping following plastic deformation, and the Yamafuji-Bauer theory for the recovery of damping following a high strain amplitude vibration. Reasonable qualitative agreement is obtained between the Granato-Lücke theory and the observed dependence of the damping and modulus on strain amplitude and temperature. Reasonable quantitative values for the dislocation density, network node loop length, and activation energy for the migration of vacancies in magnesium are obtained. It is found that in order to get agreement with the decay of the damping during annealing at high temperature, it is necessary to modify the Granato-Hikata-Lücke theory. This is accomplished by replacing the Cottrell-Bilby expression for the segregation of pinning points to dislocations by an expression suggested by Harper to account for longer times. The observed dependence of the damping on composition does not agree with the Granato-Lücke predictions. A possible explanation for this discrepancy is offered. Several new phenomena that were observed are described and discussed --Abstract, page i.

Aktueller Malariaschutz bei Kurzzeitaufenthalt

Zusammenfassung: In Deutschland werden jährlich ca. 800Malariafälle gemeldet. Für ca.1% der nicht immunen Reisenden endet die Krankheit tödlich. Um diese Situation zu verbessern, ist die Information durch die beratenden Ärzte entscheidend: das Risikobewusstsein der Reisenden vor, während und nach einer Reise in endemische Gebiete muss geschärft werden. Ein konsequenter Mückenschutz vermindert das Infektionsrisiko der Malaria sowie anderer durch Arthropoden übertragener Krankheiten zusätzlich. Die regelmäßige Einnahme von Medikamenten zur Malariachemoprophylaxe in Hochrisikogebieten sowie das rasche Handeln im Falle von Fieber in Gebieten mit mäßigem oder kleinem Malariarisiko (Aufsuchen eines Arztes zur Diagnosestellung, notfalls Selbsttherapie) tragen wesentlich zur Reduktion schwerer Malariaerkrankungen be