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Biomedical subjects

I Barth

Publications and source records attributed to I Barth.

9 recordsLinked to original sources
PubMed2007

Beta radiation exposure of medical staff and implications for extremity dose monitoring.

Sealed and unsealed beta radiation sources come into use to a greater extent in radiation therapy, e.g. for treating inflammatory joint diseases by radiosynoviorthesis (RSO), by injecting 90Y, 186Re or 169Er-solutions. Sealed 90Sr/90Y and 32P-sources or 188Re-liquid-filled balloon catheter are applied in vascular brachytherapy. Recently, 90Y-labelled antibodies are being successfully used in radioimmunotherapy (RIT) of malign lymphoma. Such practices require handling of high activities at small distances to the skin. Thus, the medical staff may be exposed to high beta doses. Investigations of the extremity exposure were performed at several workplaces, in particular during RSO treatments. The local skin dose (LSD), Hp(0,07), was measured with thin-layer TLD (LiF:Mg,P,Cu) fixed to the fingers (TLD-tapes). The findings indicate that the exposure of the staff can exceed the annual dose limit of 500 mSv when working at low protection standard. Routine monitoring of the extremity exposures with ring dosemeters appropriate to beta radiation and provided by the approved German dosimetry services was found to be needed. But even monitoring with these official 'beta-dosemeters' does mostly not give suitable results to demonstrate compliance with the dose limit. A study was conducted at RSO-workplaces in order reveal a correlation between doses measured with ring dosemeters and the maximum LSD obtained from the TLD-tapes. The results are discussed and conclusions for routine monitoring are drawn.

Beta Particles↗
PubMed2006

[Radiation exposure in (90)Y-Zevalin therapy: results of a prospective multicentre trial].

UNLABELLED: AIM of this study was the assessment of the radiation exposure from preparation and application of (90)Y-Zevalin, the measurement of the dose rate at the patient, the exposure of family members as well as the determination of the activity concentration in urine of patients. METHODS: Overall data from 31 therapeutic administrations carried out in four institutions were evaluated. During preparation and application of (90)Y-Zevalin the finger exposures of radiochemists, technicians, and physicians were measured. The dose rate of the patient was measured immediately after radioimmunotherapy. In patients treated in a nuclear medicine therapy unit, urine was collected over a two day period and the corresponding activity was determined. Family members of outpatients were asked to wear a dosimeter over a seven day period. RESULTS: During the preparation we found a maximum skin dose of 6 mSv at the average, and during application of 3 mSv, respectively. After administration of (90)Y the dose rate was 0.4 +/- 0.1 microSv/h at 2 m distance. Urine measurements yielded a cumulated 24 h excretion of 3.9 +/- 1.4% and 4.4 +/- 1.4% within 48 h, respectively, that is equivalent to 43 +/- 18 and 50 +/- 20 MBq of (90)Y, respectively. Family members received a radiation exposure of 40 +/- 14 microSv over seven days. CONCLUSION: During preparation and application of (90)Y-Zevalin appropriate radiation shielding is necessary. For family members as well as nursing staff no additional special radiation protection measures beyond those being common for other nuclear medicine procedures are necessary.

Antibodies, Monoclonal↗
PubMed2003

[Beta-radiation exposure at the finger tips during the radionuclide synovectomy].

AIM: The radiation synovectomy is a widespread therapeutic option in rheumatoid arthritis. However, data for the beta-radiation exposure are rare. The aim of this study was to determine the personal dose equivalent H(P) (0.07) of the skin of the hands. METHODS: Thermo-luminescence detectors (TLDs) were attached at all fingertips of the therapist, the radiochemist and the nurse. In summary, the measurement of beta-exposure occurred in 155 joints at 6 days with different radio-nuclides ((169)Er, (186)Re, (90)Y). RESULTS: The greatest beta exposure were show at the forefinger (L-Ff) and thumb (L-Th) of the left hand, with which the therapist (right hander) fixed the injection needle. In 52 treated finger-joints (1204 MBq (169)Er), 29 treated large joints (2405 MBq (186)Re) and 15 treated knees (3100 MBq (90)Y) we found a cumulative beta exposure over all radionuclides of 190 mSv at L-Ff and 48 mSv at L-Th. The specific beta exposure for the individual radio-nuclides showed beta exposures of 0.56 mu Sv/MBq for (169)Er and 1.52 mu Sv/MBq for (186)Re-186 at the L-Ff. With using a manipulator the beta-exposure ((90)Y) could reduced from 22,09 to 0.42 mu Sv/MBq at the L-Ff. The greatest beta exposures for the radiochemist was 119 mSv at the L-Ff for all radionuclides. CONCLUSION: In usual techniques of radiation synovectomy the (90)Y produced the greatest part of radiation exposure. Especially at the L-Ff it might exceed the German limit for the official dosimetry service at the skin ( section sign 55 Strl-SchV). Using a holding forceps we can keep the legal rules and can reduce considerably the beta exposure.

Arthritis, Rheumatoid↗
PubMed1998

Genomic difference analysis by two-dimensional DNA fingerprinting reveals typical changes in human low-grade gliomas.

Cytogenetic and molecular analyses such as allelotyping studies have revealed several genetic changes typical for human glial neoplasms. However, most studies to date have involved malignant gliomas and thus are likely to reflect late events of tumor progression. To elucidate the initial events of glial tumor growth, we performed a genome-wide search for genetic alterations in the DNA of 43 low-grade gliomas as compared to the constitutional DNA of the patients' peripheral blood leucocytes using the two-dimensional (2D) DNA fingerprint approach. Reliable results were obtained for 28 blood/tumor sample pairs (13 astrocytomas, 9 pilocytic astrocytomas, 1 oligodendroglioma, 3 oligoastrocytomas, and 2 ependymomas). DNA was digested with the restriction enzyme HaeIII and the resulting fragments were separated on 2D gels according to size and sequence in the first and second dimensions, respectively. Patterns of hundreds of spots were generated by hybridization with four different mini- and microsatellite core probes. A total of 655 to 1,122 spots could be visualized per sample. Comparison of blood and tumor spot patterns revealed two to 11 reproducible changes per patient. Most of the differences were spot losses (77.1%), while the others appeared to be gains or amplifications. Exactly the same changes were found in tumor recurrences which lacked histological signs of progression. When comparing different patients, many of the affected spots tended to cluster in particular areas of the gel as revealed by computer-aided comparison of all spot patterns. Eleven different spot clusters were identified which may correspond to several major deletion targets. This study provides the basis for the future molecular cloning of the candidate tumor suppressor genes affected by the common spot losses and will allow new insights into the genetic mechanisms of glial tumorigenesis.

Adolescent↗
PubMed1997

[Communication with patients].

A survey on patients' opinions about and needs for communication is reported. Most patients consider communication as an important part of nursing and recovery. Not only information is demanded, but also a discussion of problems and distress. Nurses are well requested to play a part herein. While most patients indicate that their communication demands are well cared for, there are also deficits. A considerable minority of patients has notable problems with solitude and lack of communication, they want personal help to cope with disease and help for better social integration. Special demands for more communication are indicated by younger patients and by women. Patients who feel severely ill and patients who suffer from pain, depression or fright say they need more communication about their feelings and fears. Frequent, long-term or immobile patients are less convinced that doctors and nurses know what is good for them. Patients with reduced mobility tend to express less interest in communication. A field for improvement may also be found within clinics: Quality of relationships between nurses and patients differ between clinics with a clear impact on quality of nursing and wellbeing of the patients.

Adaptation, Psychological↗
PubMed1995

Adherence of Candida albicans to epithelial cells: studies using fluorescently labelled yeasts and flow cytometry.

Candida albicans adherence to epithelial cells is the first step in the infectious process, but in spite of its importance, current methods for the quantitative measurement of adherence of C. albicans to epithelial cells in vitro have some serious limitations. They are based on filtration assays and either microscopic or radiometric analysis. The adherence reaction is usually carried out with a large excess of yeasts (100-fold) over epithelial cells in order to perform the microscopic analysis, which is slow, subjective and limited to 100-200 cells and thus lacks statistical power. The radiometric analysis fails to measure individual cells. A method for measuring yeast adherence that overcomes these problems has been developed. It is based on labelling the yeasts with the fluorogenic marker 2',7'-bis-(2-carboxyethyl)-5(6)-carboxyfluorescein acetoxymethyl ester (BCECF) prior to the adherence reaction, and analysing 10(4) epithelial cells by flow cytometry, while nonbound yeasts are excluded by gating. Two subpopulations of buccal epithelial cells (BECs) which differ in their mean fluorescence intensities per cell (MFIs) were observed: one with MFI which did not exceed nonspecific fluorescence, and the other with MFI as high or higher than the MFI of labelled yeasts. The two subpopulations represent yeast-free and yeast-binding epithelial cells, respectively, and the MFI increment of the BECs is a quantitative measure of the extent of yeast adherence. Control experiments confirming previously described basic features of adherence, such as enhanced adherence at increasing yeast excess, diminished adherence of trypsin-treated or heat-inactivated yeasts, and the differential adherence of various Candida species, supported the validity of the assay. The possibility of studying adherence reliably at low yeast:epithelial cell ratios, which better mimic adhesion as it occurs in vivo, is an important advantage of the assay. New findings, using this method, included the observation that exfoliated BECs from diabetic patients exhibited the same capacity for C. albicans adherence as cells from healthy controls, and that epithelial cells from early human ontogenic stages had a significantly lower adherence level than those from later stages.

Adult↗
PubMedDate not supplied

Monitoring genomic alterations with a panel of oligonucleotide probes specific for various simple repeat motifs.

Germline and somatic instability of the human genome was studied, using synthetic oligonucleotides specific for simple repeat motifs. The following probes were used: (GTG)5, (GACA)4, (GATA)4, (CT)8, (TTAGGG)3, (GT)8, (GAA)6 and (GGAT)4. Each of them is unique with respect to the target regions recognized in the genome. Thus compilation of the various fingerprint data provides a complex map of the genome (and its deviations). While the fingerprints of differentiated somatic tissues never showed any alterations, in tumor tissues (namely gliomas) many changes could be detected. Most of the latter reflect secondary karyological aberrations. In nearly one third of the gliomas, drastically amplified and apparently monomorphic DNA fragments were identified. This marker should make it possible to deal with causal pathogenetic mechanisms as well as novel diagnostic strategies.

Base Sequence↗