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R Klett

Publications and source records attributed to R Klett.

At least 19 recordsLinked to original sources
PubMed2006

The effect of the beta-emitting yttrium-90 citrate on the dose-response of dicentric chromosomes in human lymphocytes: a basis for biological dosimetry after radiosynoviorthesis.

The production of dicentric chromosomes in human lymphocytes by beta-particles of yttrium-90 (Y-90) was studied in vitro to provide a basis of biological dosimetry after radiosynoviorthesis (RSO) of persistent synovitis by intra-articular administration of yttrium-90 citrate colloid. Since the injected colloid may leak into the lymphatic drainage exposing other parts of the body to radiation, the measurement of biological damage induced by beta-particles of Y-90 is important for the assessment of radiation risk to the patients. A linear dose-response relationship (alpha = 0.0229 +/- 0.0028 dicentric chromosomes per cell per gray) was found over the dose range of 0.2176-2.176 Gy. The absorbed doses were calculated for exposure of blood samples to Y-90 activities from 40 to 400 kBq using both Monte Carlo simulation and an analytical model. The maximum low-dose RBE, the RBE(M) which is equivalent to the ratio of the alpha coefficients of the dose-response curves, is well in line with published results obtained earlier for irradiation of blood of the same donor with heavily filtered 220 kV X-rays (3.35 mm copper), but half of the RBE(M) relative to weakly filtered 220 kV X-rays. Therefore, it can be concluded that for estimating an absorbed dose during RSO by the technique of biological dosimetry, in vitro and in vivo data for the same radiation quality are necessary.

Beta Particles↗
PubMed2006

[Radiation synovectomy of the knee joint: Evaluation of bremsstrahlung-detection by using a corpse phantom].

AIM: Multiple procedures for the quantification of activity leakage in radiation synovectomy of the knee joint have been described in the literature. We compared these procedures considering the real conditions of dispersion and absorption using a corpse phantom. METHODS: We simulated different distributions of the activity in the knee joint and a different extra-articular spread into the inguinal lymph nodes. The activity was measured with a gamma-camera. Activity leakage was calculated by measuring the retention in the knee joint only using an anterior view, using the geometric mean of anterior and posterior views, or using the sum of anterior and posterior views. The same procedures were used to quantify the activity leakage by measuring the activity spread into the inguinal lymph nodes. In addition, the influence of scattered rays was evaluated. RESULTS: For several procedures we found an excellent association with the real activity leakage, shown by an r(2) between 0.97 and 0.98. When the real value of the leakage is needed, e. g. in dosimetric studies, simultaneously measuring of knee activity and activity in the inguinal lymph nodes in anterior and posterior views and calculation of the geometric mean with exclusion of the scatter rays was found to be the procedure of choice. CONCLUSION: When measuring of activity leakage is used for dosimetric calculations, the above-described procedure should be used. When the real value of the leakage is not necessary, e. g. for comparing different therapeutic modalities, several of the procedures can be considered as being equivalent.

Humans↗
PubMed2006

Biological dosimetry after yttrium-90 citrate colloid radiosynoviorthesis.

UNLABELLED: Radiosynoviorthesis (RSO) with the ss-particle-emitting nuclide yttrium-90 is an established concept for the treatment of persistent synovitis of the knee joint. The AIM of this study was to investigate the biological radiation effect on the basis of a characteristic radiation parameter. PATIENTS, METHODS: After RSO procedures with yttrium-90 citrate colloid and subsequent immobilisation of the knee, blood specimens of 10 patients were collected immediately before RSO and 11 to 13 days after the intervention. The yield of dicentric chromosomes in the lymphocytes was determined exclusively in metaphases of the first cell cycle in vitro. In addition, activity leakage was measured by wholebody bremsstrahlung-scintigraphy. RESULTS: No statistically significant increase in the number of dicentric chromosomes (26 before treatment and 34 after treatment) in 20 192 cells analyzed from the 20 blood samples could be found as a result of RSO. However, the analysis of at least 1000 cells per blood sample demonstrates a tendency for a biological radiation effect in the blood of patients on the basis of this characteristic radiation parameter. Two of the 10 RSO patients had undergone a second RSO using yttrium-90 citrate, whereby one patient displayed activity transport out of the knee joint, amounting to 6 MBq. Only for him a radiation effect (about 130 mGy per single RSO) could be calculated by biological dosimetry. CONCLUSION: Since in general, based on the analysis of dicentric chromosomes in at least 1000 lymphocytes per individual, detection limits for groups of persons after long-term exposures to low-LET radiation of 50-100 mGy are possible, we assume that RSO with yttrium-90 should be associated with a low whole-body radiation exposure.

Adult↗
PubMed2001

[A patient with Gulf war syndrome. On discussion of an uncertain disease picture].

The Gulf War syndrome represents neurological and neuropsychological disorders in veterans of the Persian Gulf war. Until today, the various symptoms observed could not be attributed to any defined disease. As a possible cause, exposure to neurotoxic agents such as the organophosphates used during the war has been suggested by many authors. We report on a 29-year-old man who suffered from dysmnesia, disturbance of orientation, cognitive impairment, and double vision. His history revealed several front-line operations in 1990 and 1991 during the Gulf War. Physical examinations showed a complex eye-movement disturbance and a horizontal nystagmus, which was neuro-ophthalmologically confirmed. The early auditory potentials referred to a brainstem dysfunction and the cognitive disturbances correlated to changes in the late-appearing component of event-related potentials (P 300). Brain imaging with CCT, MRI, SPECT, PET, and EEG and CSF showed no pathologies. Neuropsychological tests disclosed severe cognitive impairment especially concerning memory. Three-month follow-up studies in a department of psychosomatic medicine excluded a dissociative disorder as a feature of a post-traumatic stress or a conversion disorder. This is the first case of Gulf War syndrome in Germany. We focus on an unfamiliar complication after the war. The recent literature is reviewed.

Accidents, Traffic↗
PubMed2001

[Antigranulocyte scintigraphy of septic loosening of hip endoprosthesis: effect of different methods of analysis].

AIM: Diagnosis of infection with help of antigranulocyte scintigraphy near body stem is difficult because of contemporary visualisation of bone marrow. Therefore, we investigated, whether it is possible to improve the accuracy in diagnosing septic loosening of hip endoprosthesis by changing the analyzing methods. METHODS: In 28 patients, the results of a visual interpretation of late scan, a visual interpretation and a quantitative interpretation of time-activity-course were compared. These results were verified by histology respectively microbiology. RESULTS: Histological and microbiological verification found 14 septic loosening and 14 aseptic loosening of the hip prothesis. Therefore, sensitivity, specificity, negative and positive predictive value for the visual interpretation of late scan were 0.86, 0.57, 0.80 and 0.67. For visual and quantitative interpretation of time-activity-course we found 0.86, 0.79, 0.85 and 0.80 respectively 1, 0.93, 1, 0.93. For interobserver agreement we found kappa coefficients of 0.28 +/- 0.2 for visual interpretation of late scan, 0.48 +/- 0.17 for visual interpretation and 1.0 +/- 0 for quantitative interpretation of time-activity-course. CONCLUSION: In all investigated values quantitative interpretation of time-activity-course was superior to the other analyzing methods. Therefore, antigranulocyte scintigraphy for septic loosening of hip endoprosthesis should be interpreted quantitatively.

Antibodies, Monoclonal↗
PubMed2000

Comparison of HIG scintigraphy and bloodpool scintigraphy using HDP in arthritic joint disease.

AIM: Because of a similar tracer accumulation, we assumed to get the same information about synovitis in arthritic joint disease with HIG scintigraphy and bloodpool scintigraphy using HDP. Therefore, we compared retrospectively 23 patients. METHODS: In HIG scintigraphy, synovitis was diagnosed according to increasing activity from early to late image. In bloodpool scintigraphy according to an increased activity in comparison to the surrounding tissues. RESULTS: In 694 joints comparison of both scintigraphic modalities was possible, resulting in a 2 x 2 kappa coefficient of 0.93 or 0.97 by using late-phase bone scintigraphy as an anatomical marker. For intra- and interobserver agreement, 2 x 2 kappa coefficients of 0.93 and 0.88 in HIG scintigraphy, respectively 0.96 and 0.90 in blood-pool scintigraphy were calculated. CONCLUSION: This study shows an excellent agreement in the visualization of synovitis by HIG and bloodpool scintigraphy. Because of its higher objectivity and lower cost, investigation of synovitis should be performed by bloodpool scintigraphy.

Adult↗
PubMed1999

Thyroid disorders in female patients with ankylosing spondylitis.

The association between rheumatological and thyroid disorders has long been known, the most common being the association of rheumatoid arthritis and autoimmune thyroiditis. Little is known as to possible thyroid involvement in ankylosing spondylitis (AS). In 22 female patients with AS and 22 healthy age-matched control subjects parameters of thyroid gland function, rheumatic activity, as well as a subtle drug anamnesis of the rheumatic medication, and an ultrasonographic examination of the thyroid gland were determined. Thyroid function was tested by intravenous injection of 400 microg thyrotropin-releasing hormone (TRH). In parallel basal levels of reverse-T3 (rT3), calcium and anti-thyroid antibodies were estimated. In the AS-group an enlarged thyroid volume was seen in 10 cases, basal FT4, FT3 and TT3 were significantly lower, TSH and TT4 were found to be in the normal range and rT3 was significantly increased. The prevalence of anti-thyroid antibodies was significantly higher in the AS-group. The AS-patients responded as well as the controls with thyroid hormone secretion to TRH, within an observation period of 2 hours. No differences were observed in TSH response. Free serum calcium showed in both groups no significant difference. To summarize our results, female patients with AS showed a

Adult↗
PubMed1999

The value of renal scintigraphy during controlled diuresis in children with hydronephrosis.

Dynamic renal scintigraphy (DRS) during controlled diuresis is the method of choice to diagnose the functional relevance of urinary tract obstruction in children with sonographically demonstrated hydronephrosis. However, there are no commonly accepted scintigraphic criteria for surgical intervention. On the basis of our findings, we propose four stages of washout (WO) of tracer following diuresis: in stage I, WO>50%, neither further diagnosis nor intervention is necessary; in stage II, 50%>/=WO>/=12%, repetition of DRS is advised within 3-4 months; and in stage III, 12%>WO>/=5%, DRS should be repeated within 1-2 months. Only in stage IV, WO<5%, should surgery be done immediately. This procedure reduces surgical interventions by 50% without increasing the risk of residual renal damage.

Diuresis↗
PubMed1999

[Activity leakage and radiation exposure in radiation synovectomy of the knee: influence of different therapeutic modalities].

In rheumatic diseases, radiation synovectomy is a reliable method. Meanwhile, radiation synovectomy is an outpatient therapy. In addition, combination with arthroscopic synovectomy is an increasing therapeutic modality. In comparison to the hitherto inpatient modality, a greater lymphatic emigration of the radionuclide and, therefore, a higher radiation exposure is possible. In 35 patients we found radionuclide emigration in 17 cases by whole body scintigraphy, resulting in a 50%-percentile with 68.27%-confidence interval of 1.8 (0.45-4.78)% of the injected yttrium-90-activity. Comparison of 3 groups with the above mentioned therapy modalities resulted in no statistical difference (p>0.05). Because of the found radionuclide emigration, a radiation dose of 0. 1 (0.05-0,18) mSv in women and 0.2 (0.1-0.38) mSv in men was calculated. For lymph nodes, liver, spleen and whole body radiation doses of 619 (154-1644) mSv, 62 (15-165) mSv, 62 (15-165) mSv and 37 (9-99) mSv were calculated. Gonadal radiation dose can be neglected and the morbidity rate for tumors because of the whole body radiation dose is low with a value of 0.4 per thousand. Therefore, radiation synovectomy can be used unlimited by patients age and independent of the therapeutic modality.

Adult↗
PubMed1996

Imaging of dopamine receptors with [123I]iodobenzamide single-photon emission-computed tomography in neuroleptic malignant syndrome.

With the tracer [123I]iodobenzamide ([123I]-IBZM), it is possible to image dopamine receptor occupancy with single-photon emission-computed tomography (SPECT). We report follow-up examinations with IBZM-SPECT in neuroleptic malignant syndrome (NMS) to display D2-receptor availability in the acute phase and during the course of remission. A 27-year-old man was admitted with severe akinesia, rigor, tachycardia, fever, and elevated creatine phosphokinase level (CK) after neuroleptic medication. NMS was diagnosed, and treatment was started with dantrolene, amantadine, and dopamine agonists. IBZM-SPECT examination was performed on days 6, 34, 90, 107, 131, and 201. In the acute state of NMS, there was no binding of IBZM to D2-receptors. SPECT reached almost normal values on day 131, but clinical examination still showed a mild parkinsonian syndrome. With SPECT, the D2-receptor occupancy in NMS could be successfully shown in correlation with extrapyramidal signs. IBZM-SPECT may therefore serve to monitor D2-receptor occupancy in patients at risk for NMS.

Adult↗
PubMed1996

The role of magnetic resonance imaging and scintigraphy in the diagnosis of pathologic changes of the mandible after radiation therapy.

A prospective study of 85 patients with oral cancer, treated with high-dose radiation therapy, was performed to assess the value of magnetic resonance imaging (MRI) and scintigraphy for diagnosis of pathologic changes in the mandible. During postradiotherapeutic monitoring, radiation osteomyelitis occurred in 12 cases, tumor recurrences infiltrating the mandible in five cases, and progressive periodontal disease in nine cases. MRI permitted early diagnosis of radiation osteomyelitis in 11 out of 12 cases; only two cases were false positive. In scintigraphy with 99mTc-HDP, all alterations of the mandible, such as osteoradionecrosis, tumor infiltration, and periodontitis, showed a high uptake, resulting in a sensitivity of up to 100%, but a low specificity of 57%. Scintigraphy permitted assessment of the extension and location of the lesions. Both methods were superior to conventional radiography and clinical examination and should be integrated into a comprehensive follow-up program after radiation therapy.

Adult↗
PubMed1994

Chromosome banding in amphibia. XX. DNA replication patterns in Gastrotheca riobambae (Anura, Hylidae).

Replication banding patterns were induced in the chromosomes of Gastrotheca riobambae by treating cell cultures with 5-bromodeoxyuridine (BrdU) and deoxythymidine (dT). In particular, the time sequence of replication of the highly differentiated XY/XX sex chromosomes was meticulously analyzed throughout the S phase. In the homogametic female, BrdU/dT labeling revealed no evidence of asynchronous replication between euchromatic regions in the XX pair. Minor replication asynchronies between the two X chromosomes were restricted to the heterochromatic C-bands. These results are further proof that dosage compensation in Amphibia for X- or Z-linked genes does not occur by inactivation of one of the two (XX or ZZ) sex chromosomes in the cells of homogametic individuals. In the very large and almost completely heterochromatic Y chromosome of G. riobambae, the various C-bands comprise at least three different structural categories, resulting in a complex pattern of early- and late-replicating bands along the Y chromosome.

Animals↗
PubMed1989

[Effects of projection errors on the pantographic diagnosis of TMJ dysfunction].

Extraoral recording methods are bound to produce geometric projection errors. Mirror projections of the curvatures on both sides are a particular problem in clicking joints, thus complicating diagnosis. With the aid of magnetic resonance tomography it has been demonstrated in clinical examples that misinterpretations of the recordings can be avoided by means of computer-supported measuring systems providing accurate projection error correction. Furthermore, it is important that diagnosis be based not only on the usual sagittal plane recordings but also on additional information from the horizontal and frontal planes. Magnetic resonance tomography is then used to confirm the eccentric disc luxation established with the aid of the electronic recordings.

Diagnostic Errors↗
PubMed1989

[Etiology of eccentric-posterior and centric-anterior displacements of the articular disc].

40 patients with suspected intraarticular soft tissue displacement have been examined clinically and with the aid of electronic recording methods. The disc position has been verified by means of magnetic resonance tomography. Based on these results and on functional as well as anatomic considerations the development of various forms of articular disc displacement is discussed. Within the pathogenetic considerations particular attention must be paid to the role of dysfunctional excessive mouth opening and the loosening of the posterior cranial attachment of the disc on the base of the skull. This attachment is subjected to individual variations. An intact posterior cranial attachment of the articular disc via the superior stratum of the bilaminar zone at the base of the skull may result in an eccentric posterior displacement under existing dysfunctional loads. On the other hand, lack of repositioning forces due to a weak or loosening attachment may favor the development of centric anterior types of displacement.

Adolescent↗