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Biomedical subjects

R Steffen

Publications and source records attributed to R Steffen.

At least 91 records · Page 5Linked to original sources
PubMed1997

Preparation for emergency relief after biological warfare.

Upon invitation by the World Health Organization during the Gulf War, a task force "Scorpio" independent from the nations involved in the armed conflict was formed whose task was to determine whether, which and to what extent biological warfare agents had been used. risk assessment concluded that anthrax and Clostridium botulinum toxin were the major risks. The 21 civilian experts had rapidly to decide on the doctrine of operation, to assemble material which could be used and to be immunized or protected otherwise against the potential risks. Biological warfare agents may be used anywhere any time, be it by terrorists or during open or clandestine hostilities. The general population cannot rely on the military to take care of civilian relief, thus international and national organizations may wish to establish similar task forces basing on the "Scorpio" model on a national or regional basis.

Anthrax↗
PubMed1997

Tolerance of mefloquine by SwissAir trainee pilots.

Due to presumed adverse performance impact, a World Health Organization clause currently restricts the use of mefloquine malaria chemoprophylaxis in individuals requiring fine coordination and spatial discrimination. We conducted a double-blind, placebo-controlled, cross-over study to quantitatively assess the effects of mefloquine at steady state on performance in 23 trainee airline pilots. Flying performance was assessed using a flight simulator, psychomotor function was evaluated, sleep and wake cycles were monitored, and symptoms and moods were assessed using standardized questionnaires. A simplified postural sway meter recorded sway in three test positions. In the mefloquine loading dose phase, there was one withdrawal due to dizziness, diarrhea, and flu-like symptoms, and three volunteers reported nonserious, sleep-related adverse events. There was no significant difference in flying performance, psychomotor functions, or mean sway for any test position. Nonsignificant reductions in mean total nocturnal sleep (mefloquine = 450 min versus placebo = 484 min) and poorer sleep quality were detected in the mefloquine phases. The mood findings indicated a predominance of positive states, with vigor the predominant mood in all phases. No significant performance deficit was documented under laboratory conditions during use of mefloquine at steady state.

Adult↗
PubMed1997

The safety of gastrostomy in patients with Crohn's disease.

OBJECTIVE: To evaluate the safety of gastrostomy tube placement in patients with Crohn's disease. METHODS: We retrospectively reviewed the charts of 25 patients with Crohn's disease who underwent surgical or endoscopic gastrostomy tube placement. Additional follow-up information was obtained by contacting the patients by telephone. RESULTS: Twenty-five patients with Crohn's disease underwent either surgical or percutaneous gastrostomy tube placement for prolonged enteral nutrition or gastric decompression after abdominal surgery. Gastrostomies were placed without difficulty in all cases. No major complications occurred after the procedures. Minor complications occurred in five patients, including one case of local wound infection, one case of persistent pain at the gastrostomy site, and three cases of peristomal leakage. These minor complications occurred in 22% of those who underwent percutaneous gastrostomy tube placement and 16% of those who underwent surgical gastrostomy. There was a higher incidence of minor complications in those who underwent gastrostomy for gastrointestinal decompression than in those who underwent the procedure for nutritional supplementation (14% versus 3.5%). A prior history of fistula formation did not predispose to complications related to gastrostomy placement. After gastrostomy tube removal, rapid closure of the site occurred in 96%. No cases of gastrocutaneous fistula formation occurred during follow-up, which ranged from 45 days to 8.7 yr (mean = 2.6 yr). CONCLUSIONS: We conclude that gastrostomy placement is safe in patients with Crohn's disease and does not result in an increased incidence of peristomal disease or formation of prolonged gastrocutaneous fistulas after gastrostomy tube removal.

Abdomen↗
PubMed1997

Immunochemical localization of the phylogenetically oldest receptor tyrosine kinase: existence in the marine sponge Geodia cydonium.

Until now molecular data, elucidating the basis of invertebrate immunity are lacking. Previously both the gene and different cDNAs, coding for the ancestor of metazoan receptor tyrosine kinases (RTK), have been isolated from the marine sponge Geodia cydonium. The sponge RTK shows high polymorphism in the coding as well as in the non-coding parts of the gene. To further elucidate if the sponge RTK might be a molecule involved in self/non-self recognition the intracellular portion of the sponge RTK was expressed in Escherichia coli. The 59 kDa recombinant protein was used to raise monoclonal antibodies (McAb). The McAb recognized three polypeptides of sizes 135, 68 and 26 kDa by Western blotting. The McAb recognized only the plasma membranes of sponge cells as analyzed by immunohisto- and cytochemical studies. Northern blotting analysis revealed that the expression of the RTK gene depends on environmental conditions and on seasonal variations. Based on the high degree of polymorphism and on the immunochemical data we suggest that the RTK in G. cydonium might be involved in sponge immunity.

Animals↗
PubMed1997

[Melatonin--clinical perspectives in prevention and therapy].

Melatonin is a hormone produced by the pineal gland mainly during the night. Its primary function is to coordinate biological rhythms. It may be used for therapy of chronobiological disorders, such as occur in jet lag, shift work, blind persons or in specific forms of insomnia. Due to its anti-gonadotropic effect, melatonin in high doses has been used as a contraceptive. In-vitro and animal studies have demonstrated cancer inhibition, immun-stimulating and rejuvenating effects, but none of these claims have been confirmed in clinical studies. Melatonin used over a short period is not associated with significant side-effects, but the tolerability of long-term administration is unknown. As the products are not always of pharmaceutical quality, one should avoid uncontrolled use of melatonin.

Animals↗
PubMed1997

Cathepsin, a major protease of the marine sponge Geodia cydonium: purification of the enzyme and molecular cloning of cDNA.

Sponges are suspension-feeders that are devoid of body cavities. Phagocytosis is the major route of nutrition in these animals. In an attempt to understand protein digestion, cathepsin was identified in crude extracts from the sponge Geodia cydonium. This enzyme was purified from lysosomes by a two-step procedure--pH precipitation and FPLC separation--to apparent homogeneity; it showed an M(r) of 26,000. Inhibitor as well as substrate studies showed that the sponge cathepsin belongs to the subfamily L of these cysteine proteases. The complete cDNA coding for cathepsin L was isolated and characterized. The deduced aa sequence contains 322 residues, has an M(r) of 36,085, and shows the characteristic signatures known from other cathepsins of the L subfamily: e.g., cleavage site for the proregion, the ERFNIN motif, and the conserved regions forming the catalytic triad of cysteine proteases. Phylogenetic analyses revealed that the sponge sequence groups with the cathepsin L subfamily and branches off first from the other metazoan members. The sponge sequence shows high homology to that isolated from Dictyostelium discoideum and only low similarity to the protozoan cathepsins L from Paramecium tetraurelia and Tetrahymena thermophila. From the data presented it is concluded that cathepsin L is the major digestive protease in sponges.

Amino Acid Sequence↗
PubMed1997

[Reserve treatment for malaria: pros and cons].

Any discussion of stand-by treatment will raise several questions: to whom should it be prescribed? which drugs are advised for stand-by treatment, according to the expected sensitivity of the parasites, the chemoprophylaxis and the possible side effects of the drugs chosen? what information should be given to a potential user? under what circumstances should stand-by treatment be used? how can the use of stand-by treatment and its efficacy be evaluated? are there any data for the stand-by treatment in literature? what are the pros and cons for the use of stand-by treatment? what is the place for stand-by treatment in today's array of antimalarial treatment? All of these questions were discussed at a round table stating that while stand-by treatment is an important element in malarial prevention for travellers, it must not become synonymous with self-treatment. An initial prescription of stand-by treatment is essential with the physician informing the user of the conditions for its use and its risks. The use of stand-by treatment does not exempt the traveller from rigourously carrying out the extensive recommended preventive measures. If, in spite of these precautions, a traveller does come down with a presumed malarial fever, the use of stand-by treatment should not prevent him from consulting a physician. A physician is in the best position to indicate an available stand-by treatment which should be considered as a back-up treatment. Self-treatment should only be considered as a last resort given its limitations. In all cases, it is indispensable to consult a physician.

Acute Disease↗
PubMed1997

[Risks for travelers].

Explore the source record for details and available documents.

Communicable Disease Control↗
PubMed1996

Malaria Prophylaxis in Different Age Groups.

Background: There is a perceived increased health risk in senior visitors to malaria endemic countries. Methods: The authors sought to compare effectiveness and tolerability of malaria chemoprophylaxis in senior travelers (>=60 years) with those in younger travelers (20-59 years). The "Malpro 2" database consists of more than 100,000 questionnaires completed by travelers on charter planes returning from East Africa to Europe during July 1988-December 1991. Among them, 9106 (9.1%) of the travelers were 60 years or older, and 84,562 (84.6%) of the travelers reported to be 20-59 years. Variables of demography, travel data, and the effectiveness and tolerability of chemoprophylaxis were compared in the two subgroups. Results: Malaria in Africa was reported by 8 (1/1000) elderly travelers and by 189 (2.2/1000) travelers aged 20-59 years. Adjusting for age, sex, prophylaxis, and duration of stay in Africa in a logistic regression model, malaria was significantly more frequent in younger than in senior travelers (p<.05). Any travel-associated illness was reported by 7.0% in the senior age group and by 13.6% in the younger age group (p<.05). The rates of travelers who indicated they had "side effects" attributable to malaria prophylaxis varied between 9.7% in the elderly and 15.5% in the younger travelers (p<.05). Conclusion: Senior travelers tolerate malaria chemoprophylaxis and visits to the tropics at least as well as younger travelers.

Journal Article↗
PubMed1996

Vaccinations for travelers: new technology, new vaccines, new strategies.

To improve compliance with vaccines and to achieve greater efficacy, a new generation of vaccines is needed. These may be combinations of existing vaccines, but much more exciting are prospects of new formulations with controlled release and novel adjuvants. The ultimate goal is one single injection (or, even better, oral dose, but this is difficult to achieve) in childhood, and another when subjects such as travelers start to expose themselves to specific infectious risks.

Adjuvants, Immunologic↗
PubMed1996

[Routine immunization of infants in the Canton of Zurich].

At present there is a shortage of data regarding the rate of routine immunization in Swiss children. To address this deficit, a representative cross sectional study was conducted in the Canton of Zurich with 210 children aged between 24 and 36 months. Data was taken from the individual official vaccination certificates. 178 vaccination certificates (55.1% female and 44.9% male) were evaluated, corresponding to a response rate of 84.8%. With children of foreign nationalities, the response rate was 66.7%, whereas the response rate of Swiss children was 90.6% (p < 0.001). The response rate of children of a European nationality outside the European Union was especially poor (33.3%). The immunization rate with three doses of diphtheria, tetanus and poliomyelitis vaccines was 99.4%, and that of the pertussis vaccine was 93.3%. With the vaccines for measles, mumps and rubella the rates were 80.3%, 78.1% and 77.5% respectively. Vaccination rate against Haemophilus influenzae type B was 74.7% with two doses, and 61.2% with three doses. The timing and the number of doses of the vaccines used for infants in the Canton of Zurich were satisfactory. However, the vaccination rate for measles, mumps and rubella is inadequate. Attention should be paid to this problem and also to possible insufficient care of foreign children.

Child, Preschool↗
PubMed1996

Regulation of motility of cells from marine sponges by calcium ions.

Sponges are known not to contain muscle and nerve cells. Since sponge cells are characterized by high motility we determined the effect of intracellular calcium ion concentration ([Ca2+]i) on their motility. Addition of the Ca2+ ionophore ionomycin to dissociated cells from the marine sponge Suberites domuncula caused in Ca(2+)-containing artificial seawater (ASW) an increase in motility from 0.2 micron/min (absence of the ionophore) to 3.7 microns/min (presence of ionomycin). When the experiments were performed in Ca(2+)-free medium, no effect of ionomycin could be observed. In parallel experiments the changes of [Ca2+]i using the dye Fura-2 were measured. The experiments revealed that ionomycin causes an influx of Ca2+ into the cytosol of cells suspended in Ca(2+)-containing artificial seawater. In contrast, if cells were suspended in Ca(2+)-free artificial seawater, no increase of [Ca2+]i occurred. Incubation of cells in the presence of inhibitors, specific for endoplasmatic Ca(2+)-ATPase in mammals such as thapsigargin, cyclopiazonic acid, or 2,5 di-t-butylhydrochinone, did not influence the [Ca2+]i if cells were suspended in Ca(2+)-free artificial seawater. From these data we conclude that the [Ca2+]i is primarily regulated through channels in the plasma membrane. In addition we summarize experimental evidence indicating that the [Ca2+]i is involved in the control of cell motility. From the marine sponge Geodia cydonium a partial sequence of the myosin cDNA has been cloned. The deduced amino acid sequence comprises highest homology to nonmuscle myosin type II found in higher invertebrates and vertebrates. Taken together, these data show that the [Ca2+]i level in sponge cells can be modulated by incubation with ionomycin. An increase of the Ca2+ level parallels with higher motility of cells, suggesting an activation of Ca(2+)-dependent protein kinases of myosin type II. Investigations on the ionomycin-activated influx of Ca2+ into the cytosol revealed that predominantly the Ca2+ channels in plasma membrane control the level of [Ca2+]i.

Amino Acid Sequence↗
PubMed1996

Mefloquine tolerability during chemoprophylaxis: focus on adverse event assessments, stereochemistry and compliance.

This longitudinal study of travellers to Africa taking mefloquine (MQ) chemoprophylaxis aimed to quantify and assess non-serious adverse events (AE) occurring during short-term prophylaxis and relate these to concentrations of racemic MQ, its enantiomers and metabolite. A total of 420 volunteers (52% F) participated. AEs with some impact on activities were reported by 11.2% of participants including 7.9% of neurological/psychiatric symptoms. Women were more likely to report AEs (P = 0.02). The standardized questionnaires used showed more pathological indicators in travellers who reported subjective AE with significantly more dizziness, distress, sleep disturbances and a high total mood disturbance (TMD) in the AE group. There was, however, no significant performance deficit in computerized psychomotor tests in those experiencing AE. Furthermore, no significant differences were observed in enantiomer ratios, metabolite concentrations, or racemic MQ levels in participants with or without AEs suggesting that these factors are not the main predictors of mefloquine intolerability.

Adolescent↗
PubMed1996

A galectin links the aggregation factor to cells in the sponge (Geodia cydonium) system.

The cDNA for the full-length lectin from the marine sponge Geodia cydonium was cloned. Analysis of the deduced aa sequence revealed that this lectin belongs to the group of galectins. The full-length galectin, which was obtained also in a recombinant form, has an M(r) of 20,877; in the processed form it is a 15 kDa polypeptide. The enriched aggregation factor from G.cydonium also was determined to contain, besides minimal amounts of the galectin, a 140 kDa polypeptide which is involved in cell-cell adhesion. Monoclonal antibodies have been raised against this protein; Fab' fragments prepared from them abolished cell-cell reaggregation. Cell reaggregation experiments revealed that the aggregation factor is an essential component in the aggregation process but it requires likewise the presence of the galectin. Antibodies against the galectin blocked the aggregation factor-mediated cell adhesion. A plasma membrane component was identified (a 29 kDa polypeptide) which interacted with the aggregation factor in the presence of galectin; binding could be blocked both by antibodies against the galectin as well as against the aggregation factor. Immunohistochemical analysis revealed that spherulous cells contain the galectin but not the aggregation factor. By laser scanning microscopy, it is shown that both the aggregation factor and the galectin are located at the rim of the cells. From these data we conclude that the G.cydonium aggregation factor binds to the cells via a galectin bridge.

Amino Acid Sequence↗