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Biomedical subjects

R Steffen

Publications and source records attributed to R Steffen.

At least 109 records · Page 6Linked to original sources
PubMed1996

Polymorphism in the immunoglobulin-like domains of the receptor tyrosine kinase from the sponge Geodia cydonium.

Sponges [Porifera] are the phylogenetically oldest phylum of the Metazoa. They are provided with both cellular and humoral allorecognition systems. The underlying molecules are not yet known. To study allorecognition in sponges we first determined the frequency of graft rejection in a natural population of the marine sponge Geodia cydonium. We then determined, for the first time at the molecular level, the degree of sequence polymorphism in segments of one molecule which may be related to sponge allorecognition and host defense: the Ig-like domains from the receptor tyrosine kinase [RTK]. Thirty six pairs of auto- and allografts were assayed, either by parabiotic attachment or insertion of grafts. All of the autografts fused, while only two allografts fused and 34 pairs were incompatible. Rejection among the parabiotic allografts was characterized by the formation of a collagenous barrier, while the allografts that were inserted into the host underwent destruction. At the molecular level we first cloned to completion the 5'-end of sponge RTK, which displays a Pro-Ser-Thr-rich sequence; this is thought to act as a module of cell adhesion proteins. Then we analyzed RT-PCR products of amplification across the two Ig-like domains of RTK (about 500 bp), from two pairs of fusing sponges and one pair of rejecting sponges. High levels of polymorphism were recorded, including 18 nucleotide-substitution positions and a tri-nucleotide deletion, which translate into 13 polymorphic amino acid positions. Two of the six sponges were scored as heterozygotes. Among 9 informative polymorphic sites that were tested for linkage disequilibrium, 11 pairwise comparisons were found to be significant, implying the possibility of distinguishable alleles in this locus. To the best of our knowledge this is the first report of polymorphism in Ig-like domains of a receptor from invertebrates that may be associated with allorecognition. This data attests also that fusion in sponges is not confined to genetically identical individuals.

Amino Acid Sequence↗
PubMed1996

Hepatitis A infection in aircrews: risk of infection and cost-benefit analysis of hepatitis A vaccination.

BACKGROUND: Since a hepatitis A vaccine (HAV) with long-lasting efficacy has become available, its indication in airline crews needs to be determined. HYPOTHESIS: Destinations in developing countries are a risk factor for hepatitis A infection in airline crews, and vaccination is cost-beneficial. METHODS: Retrospective analysis was performed for all Swissair medical files for the period 1987-91. Denominator and cost data were obtained by the personnel department, and a cross-sectional seroepidemiological survey was performed in 734 Sabena staff. RESULTS: Among 3,322 Swissair crewmembers who spent an average of 45 nights in developing countries, 22 hepatitis A infections occurred. For the non-immune crewmembers, the overall annual incidence rate was 1.53 per 1000, whereas the incidence rate while staying in a high risk country was 12.2 per 1000. Cockpit crews with destinations limited to Europe had a rate of zero. Male flight attendants had a threefold higher rate as compared to female flight attendants or pilots. In Sabena, anti-HAV seroprevalence was 33.3%. Increased rates were observed in male as compared to female flying crews and in employees stationed abroad, whereas flying personnel had no higher rate than ground personnel. Simplified comparison of cost of infection and cost of vaccination indicates that vaccination may be cost-saving to the airline company for both male flight-attendants and pilots. CONCLUSIONS: Hepatitis A vaccination may be recommended to staff stationed in high risk countries and to flying crews with such destinations.

Adult↗
PubMed1996

Molecular cloning and sequence analysis of two cDNAs coding for putative anionic trypsinogens from the colonial Urochordate Botryllus schlosseri (Ascidiacea).

Botryllus schlosseri is a colonial marine invertebrate that belongs to the subphylum Urochordata. Previously we analyzed the activity of a serine protease in this species, and cloned a tunicate chymotrypsin-like molecule. In the present study we further analyzed the protease activity of this animal, and found biochemical evidence also for specific trypsin-like activity. Subsequently we utilized a degenerate polymerase chain reaction (PCR) primer to clone two B. schlosseri cDNAs coding for two different putative trypsinogens, each 243 amino acids long, that differ within the coding region in 42 amino acids and 99 nucleotides. Both clones feature the characteristics of animal anionic trypsinogens. Sequence analysis of the tunicate putative trypsinogens revealed the invertebrate characteristics of three disulfide bridges, and higher similarity to invertebrate than to vertebrate trypsinogens. We therefore propose that the typical characteristics of vertebrate trypsinogens evolved after the divergence of Urochordates and Cephalochordates.

Amino Acid Sequence↗
PubMed1996

[Video laparoscopic transperitoneal exposure of the lumbar spine for ventral fusion].

Video-laparoscopic transperitoneal ventral fusion of the lumbar spine using the Bagby-and-Kuslich (BAK) interbody fusion system combines the advantages of the conventional transperitoneal approach with the well-known advantages of minimally invasive surgery. According to our experience it is a safe procedure with an acceptable operating time, little postoperative pain, fast recovery and a short postoperative stay in hospital. Long term results need to be observed and further studies made.

Equipment Design↗
PubMed1995

Risk of Cholera Among Western and Japanese Travelers.

Background: There has been concern about an increased risk of cholera in travelers to Latin America since the spread of the pandemic to this part of the world. Additionally, before this study the continuous high incidence of imported cholera to Japan had so far not been analyzed. Methods: A retrospective analysis of cases notified in 1991 to national surveillance centers in industrialized countries and to the World Health Organization was carried out. Denominator data were obtained by the World Tourism Organization. Results: The reported rate of imported cholera in European and North American travelers visiting endemic areas remains in the range of 0,2 per 100,000, as was observed 10 years ago. This rate is, however, is manyfold higher in Japanese travelers, with a highest value of 13,0 per 100,000 reported in those returning from Indonesia, usually Bali. No secondary outbreaks were observed in those countries to which cholera was imported. Conclusions: It is assumed that the higher rates in Japanese travelers are mainly due to more intensive surveillance. On Bali and elsewhere, further studies are needed to determine both the role of V. cholerae as a cause of traveler's diarrhea in tourists and to re-evaluate the need for cholera vaccination at specific high-risk destinations.

Journal Article↗
PubMed1995

Genome size and chromosomes in marine sponges [Suberites Domuncula, Geodia Cydonium].

The genome size of the marine sponges Suberites domuncula and Geodia cydonium has been determined by flow cytofluorometric analysis using diamidino-phenylindole [DAPI]. Using human lymphocytes as reference the amount of DNA in cells from S. domuncula has been determined to be 3.7 pg and that of G. cydonium 3.3 pg. While no chromosomes could be identified in G. cydonium, the karyotype of the Suberites domuncula is 32 chromosomes in the diploid state. The size of the chromosomes was between 0.25 and 1.0 micron. No pronounced banding pattern was visible.

Animals↗
PubMed1995

Hepatitis A in travelers: the European experience.

Each year approximately 14 million Europeans travel to developing countries in Africa, Asia, and Latin American as well as to infrequently visited countries in eastern Europe. Without protection, travelers develop symptomatic hepatitis A at the rate of 3 cases per 1000 people per month of stay. Those who eat and drink under poor hygienic conditions have an even higher risk, 20/1000/month. Studies show that hepatitis A is the most frequent vaccine-preventable disease in travelers to developing countries. Immunity to hepatitis A virus is infrequent among northern European travelers, except for those born before 1945, with a history of jaundice, or who lived for > 1 year in a developing country.

Europe↗
PubMed1995

Benefit/risk considerations with respect to OTC-descheduling of loperamide.

The main criteria to be considered for releasing an antidiarrhoeal from a prescription to an OTC-drug are guaranteed quality control, established efficacy and safety and the evaluation of the drug experience on major markets. Besides the considerable benefits from a socio-economic point of view, the risk for potential inappropriate use of loperamide (CAS 53179-11-6) as self-medication can be minimized by its use being avoided in children of 5 years of age or less (e.g. by making available a solid formulation only), by limiting the treatment duration to 48 h, and by contraindicating the use of the drug in cases of fever (> 38 degrees C) and/or blood in the stools. On the basis of a broad review loperamide can be considered to be efficacious in acute non-specific, acute functional and traveller's diarrhoea. The agent has a good safety profile if the mentioned restrictions are born in mind. Loperamide thus satisfies the OTC criteria.

Adult↗
PubMed1995

Behavioural aspects of travellers in their use of malaria presumptive treatment.

The use of stand-by treatment for malaria by travellers depends on their knowledge, attitudes and behaviour. We examined the behavioural aspects of a cohort of travellers from Switzerland to low-risk malarial areas who, on recruitment, were provided with a kit containing medication for stand-by treatment, guidelines on the diagnosis of malaria, and materials for collection of blood samples for later confirmation of malaria. All subjects were urged to seek medical advice at the first signs of possible malarial symptoms. Illness (fever as the main indicator) was reported by 123 of the 1187 participants, often accompanied by shivering/chills (36.6%), headache (35.0%), gastrointestinal symptoms (69.9%), and myalgia and/or arthralgia (41.5%). Two-thirds of those ill failed to seek medical attention despite their symptoms and pretravel advice. Only 9 (7.3%) were actually beyond the reach of medical attention. The stand-by treatment was self-administered by 6 travellers, only one of whom had confirmed malaria. Two non-serious adverse events were reported. All users consulted a physician after administering the presumptive treatment. This stand-by approach is limited by inappropriate behaviour and poor malaria awareness among travellers. These negative factors can be mitigated by development of an improved kit containing a simple test for self-diagnosis.

Adult↗
PubMed1995

Efficacy and tolerance of insoluble carob fraction in the treatment of travellers' diarrhoea.

The water-insoluble carob fraction (fraction insoluble caroube, FIC, Nestlé) has been successfully used in the treatment of infantile diarrhoea. To investigate the efficacy and toxicity of FIC (1970 mg to be taken every 2 hours over a 48-hour period except during sleeping time) in the treatment of travellers' diarrhoea in adults, a double-blind, computer randomized, placebo-controlled study was conducted. Of the 755 volunteers recruited at the Zurich University Vaccination Centre, 628 (83.5%) returned their questionnaires. Among them, 164 (27.7%) had diarrhoea, but only 69 (42%) used the trial medication correctly; the others were rated non-complaint. No significant difference in efficacy (p = 0.12) or adverse effects were observed in the two study groups. In conclusion, FIC, although showed a positive trend, was not efficacious.

Adolescent↗
PubMed1995

Treatment of travellers' diarrhoea: zaldaride compared with loperamide and placebo.

OBJECTIVE: To compare zaldaride maleate, a calmodulin inhibitor with gastrointestinal antisecretory properties, with loperamide and a placebo in the treatment of travellers' diarrhoea. DESIGN: Randomized, double-blind, double-dummy study. SETTING: Study clinic staffed by European residents on Nile cruise ships. PATIENTS: Tourists (n = 436) who acquired travellers' diarrhoea during the Nile cruise. INTERVENTIONS: (1) Zaldaride 20 mg four times daily, (2) zaldaride 2 x 20 mg as initial loading dose followed by three doses of 20 mg on the first day and four doses of 20 mg on the second day, (3) loperamide 2 x 2 mg loading dose following by a flexible dosage of 2 mg after each unformed stool (maximum of 16 mg daily), (4) placebo. MAIN OUTCOME MEASURES: Number of unformed stools, rate of improvement of patients with diarrhoea, rate of relief from diarrhoea. RESULTS: Among the 331 compliant and fully evaluated patients, the zaldaride with loading dose group showed no significant differences in cure rates from the loperamide group. For most parameters, zaldaride without a loading dose and the placebo resulted in significantly lower cure rates. CONCLUSIONS: A zaldaride regimen including a loading dose was shown to be well tolerated and as effective as loperamide.

Adolescent↗
PubMed1994

Comparison of Seven Commonly Used Agents for Prophylaxis of Seasickness.

The objective of the study was to compare the efficacy and tolerability of seven drugs frequently used for the prevention of seasickness: the drugs were namely cinnarizine, cinnarizine with domperidone, cyclizine, dimenhydrinate with caffeine, ginger root, meclozine with caffeine, and scopolamine. The design was a randomized, double-blind study with two arms. On ethical grounds, a placebo group was not included as in a previous study, in the same setting, 80% of the passengers not receiving prophylactic drugs were seasick. The setting was in Andenes (Norway) during a time period from July to September 1992. Subjects were 1741 tourist volunteers who were joining a whale safari. The main outcome measures were vomiting, malaise (modified Graybiel criteria), and subjective reports of adverse events. Follow up was possible in 1489 volunteers (85.5%). In each active treatment group, 4.1-10.2% experienced vomiting and 16.4-23.5% experienced malaise (not significant). Equally, there was no significant difference in the incidence and characteristics of adverse events reported in the various medication groups. Scopolamine Transdermal Therapeutic System (TTS) users exhibited slightly more visual problems and the agent tended to be less effective. Six of the seven medications may be recommended for prevention of seasickness; scopolamine TTS seems the least attractive.

Journal Article↗
PubMed1994

Epidemiology and prevention of hepatitis A in travelers.

OBJECTIVE: To assess the risk of hepatitis A in international travelers and to recommend preventive measures. DATA SOURCES: Index Medicus, 1974 through 1983; MEDLINE, 1984 through 1993; and unpublished data of the Centers for Disease Control and Prevention. STUDY SELECTION: Review of all retrospective and cohort studies on hepatitis A and other vaccine-preventable diseases in travelers, of seroepidemiologic surveys of hepatitis A virus (HAV) antibodies in travelers, of data on the various hepatitis A vaccines, of economic analyses, and of recommendations of recognized organizations. DATA EXTRACTION: Independent analysis by multiple observers. DATA SYNTHESIS: The incidence rate for unprotected travelers, including those staying in luxury hotels, is estimated to be three per 1000 travelers per month of stay in a developing country. Persons eating and drinking under poor hygienic conditions have a rate of 20/1000 per month. This makes hepatitis A the most frequent infection in travelers that may be prevented by immunization. In many industrialized countries persons born after 1945 have an HAV antibody seroprevalence (immunity) of less than 20%. New inactivated HAV vaccines induce protective antibodies in more than 95% of recipients and offer protection estimated to last for 10 years or more, whereas protection by immune globulin lasts only 3 to 5 months. CONCLUSIONS: Hepatitis A vaccine, or immune globulin where HAV vaccine is not available, is recommended for all nonimmune travelers visiting developing countries. Prescreening for antibodies to HAV in travelers living in countries with low prevalence is usually not necessary in persons born after 1945.

Cost-Benefit Analysis↗