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Biomedical subjects

R Steffen

Publications and source records attributed to R Steffen.

At least 55 records · Page 3Linked to original sources
PubMed1999

Epidemiology, etiology, and impact of traveler's diarrhea in Jamaica.

CONTEXT: Traveler's diarrhea (TD) can incapacitate travelers. Characteristics of TD could be helpful in identifying individuals who might benefit from a vaccine against TD. OBJECTIVE: To determine epidemiology, etiology, and impact of TD in Jamaica. Design Two-armed, cross-sectional survey conducted between March 1996 and May 1997. SETTING: Sangster International Airport and 10 hotels in Montego Bay area, Jamaica. SUBJECTS: To investigate epidemiology and impact, 30369 short-term visitors completed a questionnaire just before boarding their homebound aircrafts. To investigate etiology, 322 patients (hotel guests) with TD provided stool samples. MAIN OUTCOME MEASURES: Attack and incidence rates of reported diarrhea and of classically defined TD (> or =3 unformed stool samples in 24 hours and > or =1 accompanying symptom), incapacity, risk factors, and etiology. RESULTS: The attack rate for diarrhea was 23.6% overall, with 11.7% having classically defined TD. For a mean duration of stay of 4 to 7 days, the incidence rate was 20.9% (all TD) and 10.0% (classic TD). Among airport respondents, the incapacity lasted a mean of 11.6 hours. Less than 3% of all travelers avoided potentially high-risk food and beverages. The most frequently detected pathogens were enterotoxigenic Escherichia coli, Rotavirus, and Salmonella species. CONCLUSIONS: A realistic plan for reducing TD is needed. Preventive measures such as the improvement of hygienic conditions at the destination, and/or the development of vaccines against the most frequent pathogens associated with TD may contribute toward achieving this goal.

Adolescent↗
PubMed1999

[Chemonucleolysis. Development, experiences, prospects].

Concerning the so-called minimal invasive procedures currently available for the treatment of lumbar disc prolapse (percutaneous endoscopic discectomy, APLD, laser decompression, chemonucleolysis), the intradiscal application of Chymopapain represents the method with the longest period of clinical use and experience. Long-term studies have shown good clinical results. When considering of the indication and the few contraindications--particularly allergic diathesis--chemonucleolysis provides a low-risk, efficient, minimally invasive therapy that closes the therapeutic window between conservative and open surgical treatment.

Biomechanical Phenomena↗
PubMed1999

Cloning and expression of new receptors belonging to the immunoglobulin superfamily from the marine sponge Geodia cydonium.

A cDNA encoding a receptor tyrosine kinase (RTK) was previously cloned and expressed from the marine sponge (Porifera) Geodia cydonium. In addition to the two intracellular regions characteristic for RTKs, two immunoglobulin (Ig)-like domains are found in the extracellular part of the sponge RTK. In the present study it is shown that no further Ig-like domain is present in the upstream region of the cDNA as well as of the gene hitherto known from the sponge RTK. Two different full-length cDNAs have been isolated and characterized in the present study, which possess two Ig-like domains, one transmembrane segment, and only a short intracellular part, without a TK domain. The two deduced polypeptides were preliminarily termed sponge adhesion molecules (SAM). The longer form of the SAM, GCSAML, encodes a deduced aa sequence, GCSAML, which comprises in the open reading frame 505 amino acids (aa) and has a calculated Mr of 53911. The short form, GCSAMS, has 313 aa residues and an Mr of 33987. The two Ig-like domains in GCSAML and GCSAMS are highly similar to the corresponding Ig-like domains in the RTKs from G. cydonium; the substitutions on both the aa and nt level are restricted to a few sites. Phylogenetic analyses revealed that the Ig-like domain 1 is similar to the human Ig lambda chain variable region, while the Ig-like domain 2 is related more closely to the human Ig heavy chain variable region. Transplantation experiments (autografting) were performed to demonstrate that the level of expression of the two new genes, GCSAML and GCSAMS, is upregulated during the self/self fusion process. Immunohistochemical analyses using antibodies raised against the two Ig-like domains demonstrate a strong expression in the fusion zone between graft and host. This finding has been supported by northern blotting experiments that revealed that especially GCSAML is strongly upregulated after autografting (up to 12-fold); the expression of GCSAMS reaches a value of 5-fold if compared with the controls. The results presented here demonstrate that the expression of the new molecules described, comprising two Ig-like domains, is upregulated during the process of autograft fusion.

Amino Acid Sequence↗
PubMed1999

Feasibility of a rapid dipstick antigen-capture assay for self-testing of travellers' malaria.

This open comparative study sought to determine whether, and with what level of instruction, travellers can successfully use and interpret the rapid whole blood malaria diagnostic test, ParaSight F. 160 visitors to the Zürich University Travel Clinic took part in the study. One group received written instructions only, while another group was given combined oral and written instructions on how to test their own blood for malaria infection and interpret a series of 5 prepared test strips. Each volunteer also completed a questionnaire targeted at assessing performance in using the diagnostic, interpretation of the results and acceptability of the concept of self-testing for malaria infection. The main outcome measures were successful performance of the test, correct interpretation of prepared test strips and acceptability of the test. In the group which received only written instructions, 60/80 (75%) were successful, whilst in the group which received written and oral instructions, 72/80 (90%) successfully performed the test (P < 0.02). Overall, 565 (70.6%) test strips were correctly and 165 (20.6%) incorrectly interpreted with 113 (14.1%) false negative interpretations. No prepared test strip was interpreted as false positive. Seventy (8.8%) test strips were not interpreted. Some 91. 9% of all candidates would use such a test if it were available. While it is possible for lay persons to successfully perform the test, interpretation of results poses a problem. In particular, the proportion of false negative interpretations is unacceptable. A combination of written and oral instructions leads to a significantly higher level of successful test performance. If such a test is to be made available to the general public, written instructions must be made concise and foolproof and the test endpoint clearly defined, as the currently available test is more suitable for trained laboratory personnel. In the meantime other candidate diagnostics have become available and these should now be assessed for their suitability in the context of travellers' malaria.

Adolescent↗
PubMed1999

Improved detection of enterotoxigenic Escherichia coli among patients with travelers' diarrhea, by use of the polymerase chain reaction technique.

This study sought to determine whether a specific polymerase chain reaction (PCR) for enterotoxigenic Escherichia coli (ETEC) toxins after chaotropic extraction of DNA from stool would increase the detection of ETEC over that of conventional oligonucleotide probe hybridization of 5 E. coli colonies per stool sample (a standard method). By DNA hybridization, 29 (21%) of 140 patients were positive for ETEC, and 59 (42%) of 140 were positive for ETEC when PCR was used. Sensitivity of the PCR assay was confirmed through spiked stool experiments to be approximately 100-1000 ETEC colonies per sample. Specificity of the assay was determined by showing an absence of ETEC by the PCR technique in a subgroup of 48 subjects and by confirming the presence of ETEC DNA of positive samples by dot blot procedure. PCR technique detected significantly more ETEC infections in these subjects than did the hybridization method (P<.0001).

Bacterial Toxins↗
PubMed1999

Vaccination of travelers against hepatitis A and B.

Despite the fact that effective preventive measures have become available, there has been no decline in the incidences of both hepatitis A and hepatitis B in most industrialized countries to date. This is, in part, due to the rapid increase in the number of travelers to areas of medium and high endemicity for both diseases, primarily developing countries. Targeting of travelers at risk of contracting these diseases for vaccination offers a chance of significantly reducing their incidence. Hepatitis A, an acute disease associated with poor food hygiene, is the most common vaccine-preventable infection in travelers. Hepatitis A immunity should, therefore, be considered essential for anyone visiting an area of high endemicity. In contrast, hepatitis B is a blood-borne virus which was thought, until recently, to pose a relatively low risk to the majority of travelers. However, the 1990s has seen international tourism and business travel grow faster in Europe than anywhere else in the world, with travel to areas of high endemicity for hepatitis B (Africa, Asia and South America) being commonplace. Thus the number of reported hepatitis B cases is increasing in many countries. Furthermore, there is considerable overlap of high-endemicity areas of hepatitis A and hepatitis B so that travelers are often considered to be at risk from both viruses. As well as separate hepatitis A and B vaccine preparations, a combined hepatitis A and B vaccine is now available which may offer improvements in vaccination schedule, enhanced patient compliance, and reduced cost.

Developing Countries↗
PubMed1999

Differential expression of allograft inflammatory factor 1 and of glutathione peroxidase during auto- and allograft response in marine sponges.

Very recently, Porifera (sponges) have been proven to be suitable model systems to study auto- and allograft recognition at the molecular level. Several potential immune molecules have been isolated from the marine sponges Suberites domuncula and Geodia cydonium, among them those which comprise Ig-like domains in their extracellular part. Here we report on the isolation of two cDNAs from S. domuncula that code for molecules involved in mammals in cytokine-mediated graft response; a putative allograft inflammatory factor 1 (AIF-1) and a non-selenium glutathione peroxidase (GPX). Both polypeptides share high similarity with the corresponding mammalian proteins. The expression of the two genes during auto- and allograft recognition in S. domuncula and G. cydonium was determined. It is shown that the expression of the AIF-1-related gene is upregulated only in allografts, while the GPX-related gene is expressed in the fusion zones formed between auto- as well as allografts. Taken together, these findings suggest that besides cell-mediated defense reactions a cytokine-dependent immune response is also elicited during graft recognition in sponges.

Amino Acid Sequence↗
PubMed1999

Swedish adjustable gastric band (SAGB)-distal gastric bypass: a new variant of an old technique in the treatment of superobesity and failed band restriction.

BACKGROUND: Dissatisfied with vertical banded gastroplasty in superobese patients, the authors adopted Salmon's gastroplasty/distal gastric bypass (DGBP) in 1995. When the Swedish adjustable gastric band (SAGB) became available in Switzerland, the authors started using that device instead of the gastroplasty because implanting a SAGB is much easier and gastric restriction with a SAGB is adjustable to the patients' individual demands. METHODS: The authors evaluated 40 consecutive patients with SAGB-DGBP (27 primary and 13 secondary operations) for weight loss and complications, and compared weight loss with that obtained by SAGB alone. The mean initial body weight was 156.6 kg in women and 188.1 kg in men for primary and 108.2 kg/147.0 kg for secondary indications, respectively. The band was placed in a high position without tunneling sutures, and DGBP was done with a 50- to 60-cm common channel and a 60- to 80-cm biliopancreatic limb. RESULTS: Weight loss at 1 year was 33.3% of initial body weight for primary operations. Weight loss was significantly more than with SAGB-alone cases. Complications were as follows: no death, no slipping or pouch dilatation; one marginal ulcer, one splenectomy, four cholecystectomies, one Roux-en-O reconstruction, two band leaks, eight port-related reoperations. Iron or vitamin deficiencies occurred in 75% of patients, with one case of transient protein malnutrition and one of intermittent diarrhea. CONCLUSIONS: The SAGB as gastric restriction in combination with DGBP can be implanted easily. The new-generation SAGB is safe, but longer follow-up is necessary. SAGB-DGBP is more efficient than SAGB alone for weight reduction. It is too early to recommend banded DGBP as a primary procedure. However, in cases of insufficient weight loss after placement of an adjustable band, adding a DGBP without removing the band is an option. Follow-up by a specialized team is mandatory.

Adolescent↗
PubMed1999

Increased expression of integrin and receptor tyrosine kinase genes during autograft fusion in the sponge Geodia cydonium.

Recently cDNAs coding for cell surface molecules have been isolated from sponges. The molecules for alpha-integrin, galectin, and receptor tyrosine kinase (RTK), obtained from the marine sponge, Geodia cydonium, have been described earlier. In the present study also the cDNA for one putative beta-integrin has been identified from G. cydonium. The deduced aa sequence comprises the characteristic signatures, found in other metazoan beta-integrin molecules; the estimated size is 95,215 Da. To obtain first insights into the molecular events which proceed during autograft fusion, the expressions of these genes were determined on transcriptional and translational level. The cDNAs as well as antibodies raised against the recombinant sponge proteins alpha-integrin, RTK and galectin were used and Northern blot experiments and immunocytochemical analyses have been performed. The results show that transcription of the two subunits of an integrin receptor as well as of the RTK are strongly upregulated after grafting; levels of > 10-fold have been determined in the fusion zone of the grafts after a 10 days incubation. Immunofluorescence studies of sections through the fusion zone support these data. In contrast the transcription of the gene encoding galectin is drastically downregulated after grafting. In a parallel series of experiments the level of the heat-shock protein-70 was determined and it was found that it remained unchanged after grafting. We conclude that integrin subunits and the RTK molecule are involved in self-self recognition of sponge.

Amino Acid Sequence↗
PubMed1999

Imported malaria (1985-95): trends and perspectives.

Malaria is frequently imported into nonendemic industrialized areas. In this study we collated data on the reported malaria cases in industrialized countries during the period 1985-95, with the object of identifying trends and promising strategies. The main outcome measures were incidence, case-fatality rates (CFRs), and attack rates in tourists returning from Kenya. Our survey showed gross underreporting and marked heterogeneity in the type and availability of national data. The total incidence or reported numbers of malaria infections in Europe increased from 6840 in 1985 to 7244 in 1995, with a peak of 8438 in 1989. The principal importing countries were France, Germany, Italy, and the United Kingdom. In the former USSR, the reported annual incidence dropped from 1145 in 1989 to 356 in 1990 after cessation of activities in Afghanistan. Among the imported species of malaria parasite, Plasmodium falciparum was identified in an increasing proportion, the CFR ranging from 0% to 3.6%, with consistently high rates in Germany. The attack rates among travellers to Kenya in 1990-95 were high, ranging from 18 to 207 per 100,000 travellers. Our findings indicate that in industrialized countries malaria is associated with a high CFR and remains a public health problem. Irregular surveillance and lack of homogeneity in the collected data hinder the assessment of incidences, risk groups, and the efficacy of chemoprophylaxis.

Developed Countries↗
PubMed1998

Sarcophytolide: a new neuroprotective compound from the soft coral Sarcophyton glaucum.

Bioactivity-guided fractionation of an alcohol extract of the soft coral Sarcophyton glaucum collected from the intertidal areas and the fringing coral reefs near Hurghada, Red Sea, Egypt resulted in the isolation of a new lactone cembrane diterpene, sarcophytolide. The structure of this compound was deduced from its spectroscopic data and by comparison of the spectral data with those of known closely related cembrane-type compounds. In antimicrobial assays, the isolated compound exhibited a good activity towards Staphylococcus aureus, Pseudomonas aeruginosa, and Saccharomyces cerevisiae. Sarcophytolide was found to display a strong cytoprotective effect against glutamate-induced neurotoxicity in primary cortical cells from rat embryos. Preincubation of the neurons with 1 or 10 microg/ml of sarcophytolide resulted in a significant increase of the percentage of viable cells from 33 +/- 4% (treatment of the cells with glutamate only) to 44 +/- 4 and 92 +/- 6%, respectively. Administration of sarcophytolide during the post-incubation period following glutamate treatment did not prevent neuronal cell death. Pretreatment of the cells with sarcophytolide for 30 min significantly suppressed the glutamate-caused increase in the intracellular Ca2+ level ([Ca2+]i). Evidence is presented that the neuroprotective effect of sarcophytolide against glutamate may be partially due to an increased expression of the proto-oncogene bcl-2. The coral secondary metabolite, sarcophytolide, might be of interest as a potential drug for treatment of neurodegenerative disorders.

Animals↗
PubMed1998

Primmorphs generated from dissociated cells of the sponge Suberites domuncula: a model system for studies of cell proliferation and cell death.

Sponges (Porifera) represent the lowest metazoan phylum; they have been shown to be provided with the characteristic metazoan structural and functional molecules. One autapomorphic character of sponges is the presence of high levels of telomerase activity in all cells (or almost all cells, including somatic cells). In spite of this fact previous attempts to cultivate sponge cells remained unsuccessful. It was found that dissociated sponge cells do not replicate DNA and lose their telomerase activity. In addition, no nutrients or metabolites have been detected that would stimulate sponge cells to divide. In the present study we report the culture conditions required for the formation of multicellular aggregates from dissociated single cells of Suberites domuncula, termed primmorphs. These primmorphs are formed in seawater without addition of further supplements, and have an organised tissue-like structure; they have been cultured for more than 5 months. Cross-sections revealed a distinct external layer covered by a continuous pinacoderm, and a central zone composed primarily of spherulous cells. After their association into primmorphs, the cells turn from the telomerase-negative state into the telomerase-positive state; a telomerase level of 4.7 total product generated (TPG) units/5 x 10(3) cell equivalents has been determined. Moreover, a major fraction of the cells in the primmorphs undergoes DNA synthesis and hence has the capacity to grow. Applying the BrdU-labelling and detection assay it is demonstrated that up to 33.8% of the cells in the primmorphs are labelled with BrdU after an incubation period of 12 h. It is proposed that the primmorph system described here is a powerful novel model system to study basic mechanisms of cell proliferation and cell interaction, as well as of morphogenesis, ageing and apoptosis.

Animals↗
PubMed1998

Sponges (Porifera) model systems to study the shift from immortal to senescent somatic cells: the telomerase activity in somatic cells.

Sponges (Porifera) represent the lowest metazoan phylum, characterized by a pronounced plasticity in the determination of cell lineages. In a first approach to elucidate the molecular mechanisms controlling the switch from the cell lineage with a putative indefinite growth capacity to senescent, somatic cells, the activity of the telomerase as an indicator for immortality has been determined. The studies were performed with the marine demosponges Suberites domuncula and Geodia cydonium. It was found that the activity for the telomerase in the tissue of both sponges is high; a quantitative analysis revealed that the extract from S. domuncula contained 10.3 TPG units per 5000 cell equivalents and the one from G. cydonium 8.3 TPG units; hence the activity reached approximately 30-20% of the activity seen in telomerase-positive reference cells. In contrast, dissociated spherulous cells from G. cydonium, after an incubation period of 24 h, contained no detectable telomerase activity. From earlier studies it is known that isolated sponge cells do not proliferate. Based on these findings it is assumed that the separation of the senescent sponge cell lineage from the immortal germ/somatic cell lineage is triggered by the loss of contact with cell adhesion factors. First evidence is included which suggests that the final progress of the senescent, telomerase-negative cells to cell death is caused by apoptosis.

Animals↗
PubMed1998

The correlation between magnetic resonance imaging and the operative and clinical findings after lumbar microdiscectomy.

Fifty-four consecutive patients were studied prospectively with magnetic resonance imaging before microdiscectomy, and the findings correlated with clinical symptoms before and after operation. A sequestrated fragment was found in 59% of cases, a subligamentous disc sequestration in 25% and a disc protrusion in 16%. The levels operated on were L4/5-36%, L5/S1-62.5%, and one at L3/4; 71% were laterally placed, 10% lay intraforaminal and 10% medial. The diameter of the protrusion was 4 mm to 13 mm for the craniocaudal extension, and 5 mm to 18 mm for the anteroposterior extension. No correlation could be found between a neurological deficit and the size of the prolapse. A positive correlation was present between the increasing degree of canal obstruction and the degree of disc degeneration determined by imaging for extrusions, subligamentous disc sequestrations and free sequestrations. Nerve root inflammation and enlargement was seen in 36% of the images, corresponding to an operative finding of 32%. Magnetic resonance imaging is a helpful pre-operative diagnostic investigation which shows structural changes in the disc and the correct localisation and size of the disc sequestration, but there was no correlation between the imaging findings and the clinical symptoms.

Adult↗
PubMed1998

The effects of a psychological preparation program on anxiety in children and adolescents undergoing gastrointestinal endoscopy.

BACKGROUND: Like adults, children often experience anxiety associated with medical procedures. The purpose of this study was to investigate the effects of a program of psychological preparation for children undergoing endoscopy. METHODS: Sixty patients aged 6 to 19 years (mean, 12.2 years) were randomized into one of two groups. Group 1 received routine preparation before endoscopy. Group 2 received psychological preparation consisting of demonstration of materials that would be encountered during the procedure, use of a doll as a model, or use of a book with photographs of a child who had previously undergone endoscopy. Patients in both groups completed the Spielberger State-Trait Anxiety Inventory in the clinic and just before endoscopy. The Observational Scale of Behavioral Distress was completed by a blinded observer during each procedure. The attending physician (blinded) assessed patient cooperation. Vital signs were recorded in clinic and just before endoscopy. Parents and patients completed questionnaires after endoscopy. RESULTS: Analysis of the Spielberger State-Trait Anxiety Inventory showed patients in group 2 were significantly less anxious before endoscopy (p < 0.0001). They also required less meperidine (p < eq 0.04) per kilogram body weight and were more cooperative during the examination (p = 0.042). There was significantly less autonomic nervous system stimulation in those who had undergone psychological preparation (change in heart rate, p < 0.001; change in systolic blood pressure, p = 0.04). Statistically significant differences were found in the patients' response to questions after endoscopy regarding perceived anxiety during the procedure (p = 0.003) and the parents' response to questions regarding their own conditions (p = 0.026) and that of their child (p < 0.001). CONCLUSION: Psychological preparation before endoscopy significantly decreases patient and parental anxiety. Such preparation may allow for a reduction in sedative medications and thereby enhance procedural safety.

Adolescent↗