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Biomedical subjects

R Schütz

Publications and source records attributed to R Schütz.

At least 19 recordsLinked to original sources
PubMed2003

A three si detector system for personnel neutron dosimetry developed by means of Monte Carlo simulation calculations.

The aim of this study was the development of an electronic detection system for personnel neutron dosimetry. Converter type silicon detectors were used for neutron detection. Measurements to obtain pulse height distributions were performed in neutron fields in the energy range from thermal to 14.8 MeV. They were compared with pulse height distributions calculated by means of Monte Carlo simulation programs, and their shapes and total count responses agreed very well. Based on these calculations a three-detector system for the measurement of the individual dose equivalent, Hp(10), was developed. Response functions of the system were calculated, and their dependence on angles from 0 degrees to 75 degrees was investigated. The detector system was exposed in several neutron fields and the agreement of the determined dose values with the reference dose values (0.1 mSv to 6 mSv) was better than a factor of 2, even for quasi-monoenergetic neutrons, and for angles in the range of 0 degrees, 30 degrees and 60 degrees. The detector system should be able to measure a dose range down to 10 microSv depending on the neutron energy.

Computer Simulation↗
PubMed1996

Parametric and non-parametric measures in the assessment of knee and hip osteoarthritis: interobserver reliability and correlation with radiology.

The aim of this study was to evaluate the interobserver reliability of parametric and non-parametric variables in the clinical assessment of hip and knee osteoarthritis (OA). Three rheumatologists examined 49 patients with different radiological stages of OA using different assessment tools such as a tape measure, a goniometer, a plurimeter and a hand-held pull gauge. The reliabilities of parametric variables calculated by analysis of variance (ANOVA) showed much higher values than the non-parametric ones calculated by Kendall's tau beta. The highest levels of correlation in hip OA between clinical functional tests and radiological changes were found for hip extension (r = 0.57; P < 0.01) and the Patrick sign (r = 0.54; P < 0.01) while in knee OA the highest correlations were found for knee circumference (r = 0.5; P < 0.01) and knee flexion (r = 0.035; P < 0.02). Knee muscle strength, as measured with a hand-held pull gauge, showed a high level of interobserver agreement (r = 0.79), but correlated poorly with radiological changes. In conclusion parametric variables of joint morphology as knee circumference of parametric variables of function as the Patrick sign should be preferred for assessing secondary endpoints in OA clinical trials.

Aged↗
PubMed1996

Bicyclo-DNA: a Hoogsteen-selective pairing system.

BACKGROUND: The natural nucleic acids (DNA and RNA) can adopt a variety of structures besides the antiparallel double helix described by Watson and Crick, depending on base sequence and solvent conditions. Specifically base-paired DNA structures with regular backbone units include left-handed and parallel duplexes and triple and quadruple helical arrangements. Given the base-pairing pattern of the natural bases, preferences for how single strands associate are determined by the structure and flexibility of the sugar-phosphate backbone. We set out to determine the role of the backbone in complex formation by designing DNA analogs with well defined modifications in backbone structure. RESULTS: We recently developed a DNA analog (bicyclo-DNA) in which one (gamma) of the six torsion angles (alpha-zeta) describing the DNA-backbone conformation is fixed in an orientation that deviates from that observed in B-DNA duplexes by about + 100 degrees , a shift from the synclinal to the antiperiplanar range. Upon duplex formation between homopurine and homopyrimidine sequences, this analog preferentially selects the Hoogsteen and reversed Hoogsteen mode, forming A-T and G-C+ base pairs. Base-pair formation is highly selective, but degeneracy is observed with respect to strand orientation in the duplex. CONCLUSIONS: The flexibility and orientation of the DNA backbone can influence the preferences of the natural bases for base-pairing modes, and can alter the relative stability of duplexes and triplexes.

Adenine↗
PubMed1996

How accurate is serologic testing of plasma pools for hepatitis B virus surface antigen, anti-human immunodeficiency virus 1 and 2, and anti-hepatitis C virus?

OBJECTIVE: The European pharmacopeia prescribes that, during the manufacture of blood derivates, the first homogeneous pool of plasma (for example, after removal of cryoprecipitate) must be tested for hepatitis B virus surface antigen (HBsAg), for hepatitis C virus (HCV) antibodies and for human immunodeficiency virus (HIV) antibodies using test methods of suitable sensitivity and specificity, in order to reduce the residual risk of infection originating from blood products. The present study was performed to verify if commercially available immunoassays, which are licensed for the screening of single serum and plasma samples, are suitable for the determination of HBsAg, anti-HCV, and anti-HIV in plasma pools. DESIGN: Plasma tools originating from different countries were spiked with HBsAg- and anti-HCV-positive standards (National Institut für Biological Standards, Hertfordshire, UK) and anti-HIV-positive serum. For the determination of HBsAg with and without immune complex dissociation (ICD), anti-HCV and anti-HIV antibodies the Abbott (Delkenheim, Germany) IMx system was used. RESULTS: In contrast to the testing for anti-HIV and anti-HCV, the detection of HBsAg (0.125 IU/ml detection limit) was influenced by the presence of anti-HBs in plasma pools. Statistically significant differences could be observed between anti-HBs-positive plasma pools and anti-HBs-negative serum samples spiked with HBsAg. The kinetics of HBsAg-anti-HBs complex formation showed that in a plasma pool with a high anti-HBs (329.4 IU/ml) concentration HBsAg was not detectable after 5 h of incubation. After ICD, HBsAg was still detectable in the pool with high anti-HBs content. Anti-HIV antibodies could be detected up to a dilution of 1/480,000, anti-HCV up to a dilution of 1/80, both in a spiked negative serum. Overall, the divergences between spiked plasma and serum were relatively low for anti-HCV and anti-HIV detection. CONCLUSION: The Abbott IMx assay permits a highly sensitive detection of HBsAg (after ICD or immediately after thawing of anti-HBs-positive plasma pools), anti-HCV, and anti-HIV in plasma pools. However, in case of a contamination with donations originating from individuals with acute HBV, HIV, or HCV infection or with a poor humoral immune response, serologic testing for HBsAg, anti-HIV, and anti-HCV may fail to detect potentially infectious plasma pools.

AIDS Serodiagnosis↗
PubMed1995

Development and biochemical characterization of a double-virus-inactivated factor VIII preparation.

This paper describes the development of a double-virus-inactivated preparation. The original goal was to inactivate and/or remove parvovirus from plasma-derived factor VIII. More recently, attention has also been focused on the controversial issue of transmission of the non-lipid-coated hepatitis A virus by preparations of factor VIII which have been solvent/detergent-treated and purified by ion-exchange chromatography.

Antiviral Agents↗
PubMed1994

Extraction of Triton X-100 and its determination in virus-inactivated human plasma by the solvent--detergent method.

For inactivation of lipid-enveloped viruses during the production of fresh frozen and lyophilized human plasma, the solvent-detergent method was applied. In this process, the solvent tri-n-butyl phosphate is removed by extraction with castor oil. The removal of the non-ionic detergent Triton X-100 is performed by solid-phase extraction using reversed-phase supports. For this purpose, different polymer- and silica-based supports were tested. The highest capacity for Triton X-100 was achieved with C18 silica gels. These supports can bind more than 0.1 ml of Triton X-100 per ml of support. None of the proteins, e.g., clotting factors, bind to the support and therefore they pass through the column and their biological activity is hardly affected. The determination of detergent during the production process was also studied. The application of special columns allowing direct sample injection was introduced. This is a simple method for the rapid in-process determination of Triton X-100 in human plasma by reversed-phase chromatography under isocratic conditions. Using the method developed here, less than 1.0 ppm of Triton X-100 can be detected in less than 12 min without any sample pretreatment.

Blood↗
PubMed1994

A solvent I detergent treated, pasteurised and highly purified factor VIII concentrate.

In an assessment of the risks of virus transmission by clotting concentrates it is clear that the currently practised procedures for virus inactivation are not equally effective against all types of viruses; neither a pasteurisation nor the solvent detergent (SID) process alone are adequate enough to inactivate viruses that are strongly resistant to heat and organic solvents. In this context, human parvovirus B19 and hepatitis A virus (HAV) are of particular concern. In order to improve this situation which still poses a risk to the haemophiliac patients, a more effective pasteurisation process has been developed that could be easily applied to an already well established factor VIII (FVIII) process in addition to the SID-treatment. Experiments using temperatures above 60 degrees C were performed prompted by two recent publications, which demonstrate that HAV becomes instable at temperatures exceeding 62 degrees C. It is the purpose of this paper to present the following progress: achievement of a pasteurisation procedure for FVIII at 63 degrees C for 10 h with no discernible change in the structure of the factor VIII/von Willebrand factor (FVIII/VWF) complex owing to a newly developed composition of stabilizers; application of this pasteurisation procedure to a purified FVIII fraction that has already been submitted to a SID-treatment: Doing so, two independent virus inactivation steps are performed as previously recommended by the International Association of Biological Standardization (IABS). Introduction of a second purification step on an anion exchange resin, achieving an additional virus reduction over the presently manufactured FVIII preparation.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Protein Electrophoresis↗
PubMed1989

[Cibenzoline: electrophysiologic effects of a new class I anti-arrhythmia agents in supraventricular tachycardia].

Cibenzoline, an imidazoline derivate, is a new class 1 antiarrhythmic agent. The electrophysiologic effects and antiarrhythmic properties of cibenzoline (100 mg i.v.) were evaluated in 22 patients with paroxysmal supraventricular tachycardia: 12x Wolff-Parkinson-White Syndrome, 9x AV nodal reentrant tachycardia, 1x atrial tachycardia. Cibenzoline shortened the sinus cycle length from 742 +/- 103 ms to 661 +/- 87 ms (p less than 0.001) and the sinus node recovery time from 1026 +/- 106 ms to 926 +/- 135 ms (p less than 0.001). The substance lengthened the AH interval from 93 +/- 19 ms to 112 +/- 24 ms (p less than 0.001) and the HV interval from 42 +/- 12 ms to 61 +/- 14 ms (p less than 0.001). The effective refractory periods of the atrium and right ventricle did not change significantly, but the effective refractory period of the AV node in antegrade (269 +/- 42 ms vs 278 +/- 46 ms; p less than 0.05) and retrograde direction (281 +/- 57 ms vs 413 +/- 124 ms; p less than 0.001) increased markedly. Cibenzoline prolonged the effective refractory period of the accessory pathway in retrograde direction from 263 +/- 41 ms to 428 +/- 101 ms (p less than 0.001). The effective refractory period of the antegrade accessory pathway did not change. During atrial stimulation inducibility of the reentrant tachycardia was suppressed in 14 of 22 patients and the inducibility of atrial fibrillation in 7 of 12 patients. The RR interval of the reentrant tachycardia was prolonged from 353 +/- 57 ms to 420 +/- 57 ms (p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

[Contact allergy to rubber, surgical and vinyl gloves].

Thirty-one patients with a contact allergy to gloves made from rubber or vinyl were investigated in a retrospective and prospective study. Sensitivity to rubber gloves used in the household and in industry occurred most frequently (64%), followed by surgical gloves (26%) and vinyl gloves (10%). Health service worker and housewife were the professions in which the allergy was most frequently present. The main sensitizers were found to be the rubber accelerators of the thiuram and carbamate group. A series of various gloves (household, surgical, vinyl) yielded extremely different results when tested epicutaneously on the rubber-sensitized individuals. Vinyl gloves, surgical gloves made from pure latex or surgical gloves with an inner plastic coating may alternatively be used by these patients.

Dermatitis, Contact↗
PubMed1986

[Group occupational medicine of the Swiss Accident Insurance Institute ].

According to the Swiss Federal Accident Insurance Law, the Swiss National Accident Insurance Company (Suva) is responsible for the prevention of occupational disease in all Swiss industries. In the Suva medical division, a special group concerned with occupational medicine ensures that these measures are implemented. It first of all organizes and supervises preliminary check-ups and follow-up examinations and then may also exclude endangered employees from their present activity. Such employees are entitled to free advice and in certain cases may qualify for interim daily allowances.

Air Pollutants, Occupational↗
PubMed1982

[Granulocyte migration in vitro in psoriasis patients induced by aromatic retinoid].

The influence of the aromatic retinoid Ro 10-9359 on the migration of neutrophilic granulocytes was examined in standardized supravital preparation. For this purpose, leukocytes were taken from 5 psoriasis patients who had been treated with 75 mg of aromatic retinoid for 3 weeks. The examinations showed that the course of granulocyte migration was disturbed: the dormant stage was prolonged up to several hours. Maximum cell motility was already reached in that stage of motion in which the granulocytes maintained a constantly changing and bizarre cell pattern. The migration stage, which is characterized by a directed linear cell movement, was absent. Leukocyte survival time was shortened by 50%, and cell degeneration was abnormal under the influence of the aromatic retinoid.

Cell Migration Inhibition↗
PubMed1982

[Immunological staging in lupus erythematosus. Basic data and practical significance].

A complete staging of immunity in lupus erythematosus includes immunoserologic, immunocytologic, and immunohistologic findings. However, not all of these laboratory findings are of clinical relevance. The most important immunologic parameters for lupus erythematosus can be summed up in three obligatory and two facultative tests. This "immunologic staging" is considered to be of decisive importance for the risk classification of patients with lupus erythematosus and for the choice of the therapeutic procedure.

Antibodies, Anti-Idiotypic↗
PubMed1982

[Side-effects of atropine: pharmacological, allergic, pseudo-allergic or toxic reactions?].

Between 1979 and 1981 31 children aged from one to 14 years who had been given atropine eye drops to measure refraction presented with the following side-effects: increased temperature (9/31), dry red skin (8/31), reddened eye (3/31) and periorbital dermatitis (2/31) after single (22/31) or repeated (9/31) administration of atropine. In the epicutaneous test with atropine eye drops 1% (readings after 24, 48 and 72 hours) not a single child showed an allergic or toxic reaction. The rarity of an allergy after administration of atropine drops is emphasized by the fact that periorbital dermatitis was observed in only two cases. Clinical experience shows that incipient allergy owing to the anatomical structure of the conjunctiva and eye lids first becomes apparent in the region of the eye, even if the epicutaneous test is not necessarily positive in the dorsum skin. In view of the necessity of administering atropine prior to emergency surgery it is advisable to carry out epicutaneous tests if side-effects have been observed in the eye, to make sure that the patient is not allergic to the drug.

Adolescent↗