Biomedical subjects

J Pinkert

Publications and source records attributed to J Pinkert.

11 recordsLinked to original sources

PubMed2006

Therapeutic status of radiosynoviorthesis of the knee with yttrium [90Y] colloid in rheumatoid arthritis and related indications.

Radiosynoviorthesis (RSO) with an yttrium-90 colloid offers a local and minimally invasive therapy for treating inflammatory hypertrophy of the synovial membrane of the knee that has arisen from numerous kinds of disorder: these include rheumatoid arthritis (RA), osteoarthritis (OA), spondyloarthropathy, villonodular synovitis and others. There is substantial evidence that this treatment is efficacious and that, in view of the benefits that it offers, its tolerability and safety are very good. Administration should be restricted to patients in whom other therapies (including locally injected corticoids) have failed, and proper attention must be paid to correct administration, including post-treatment immobilization and the co-administration of corticoids, to minimize the risk of leakage and of efflux through the puncture channel.

Arthritis, Rheumatoid↗

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↗

PubMed2005

[Radioimmunotherapy with yttrium-90 ibritumomab tiuxetan. Clinical considerations, radiopharmacy, radiation protection, perspectives].

90Y-ibritumomab tiuxetan (Zevalin) is currently approved for radioimmunotherapy of patients with relapsed or refractory follicular non-Hodgkin's lymphoma pretreated with rituximab. Future directions are the combined use of 90Y-ibritumomab tiuxetan as part of the initial treatment and as first-line multi-agent therapy of relapsed disease. Current studies investigate patients with other than follicular indolent histologies, e. g. diffuse large cell lymphoma. Labelling of 90Y ibritumomab tiuxetan is a safe procedure, the radiochemical purity is not disturbed by a higher room temperature or by metallic impurity. Quality control is recommended by thin layer chromatography (TLC), strips >15 cm are favourable. TLC cannot distinguish between the correctly radiolabelled antibodies and radiocolloid impurity. If necessary, additional HPLC should be performed. Radiocolloid impurities are absorbed to the solid phase and do not reach the eluate. If the radiochemical purity test is insufficient (<95%), the additional cleaning using EconoPac 10 DG columns (Biorad, Hercules, CA, USA) is a reliable procedure to reduce the percentage of free radionuclide. However, this procedure is not part of the approval.

Anemia↗

PubMed2003

Persistent vegetative state: evaluation of brain metabolism and brain perfusion with PET and SPECT.

Patients in persistent vegetative state (PVS) after severe head trauma were investigated with 99mTc-ECD SPECT and 18F-FDG PET to further characterize the degree of brain damage and to obtain insight into changes of brain perfusion and glucose metabolism. 18F-FDG PET and 99mTc-ECD SPECT were performed in 16 patients in PVS. Quantitative PET data were compared with that obtained from seven normal controls. After spatial normalization into Talairach space, global grey matter values and regional data using predefined ROI sets were derived. For comparison of PET and SPECT, regional data were normalized to their individual mean grey matter values. Patients in PVS showed significantly lower values of cerebral glucose metabolism than did the controls. The mean reduction of grey matter values in cortical and subcortical structures was 58%, except in the vermis cerebelli, where only a reduction of 16% was found compared to the controls. Comparing the glucose metabolism and perfusion within the patient group, the pattern of both modalities was similar in the neocortex and internal ganglia. In the cerebellar hemispheres a relatively higher perfusion than glucose metabolism was found. The overall reduction of 58% of glucose metabolism in grey matter structures is in accordance with other PET studies investigating PVS patients with different disease histories. The relative preserved activity of vermis cerebelli seems to be an uncommon finding not described by other authors up to now.

Adolescent↗

PubMed2001

[Symptomatic cyst of the pancreas and asymptomatic bilateral phaeochromocytoma]

Symptomatic cyst of the pancreas and asymptomatic bilateral phaeochromocytoma. HISTORY AND CLINICAL FINDINGS: A 39-year-old woman was admitted to our department of gastroenterology with recurrent epigastrical pain. Ten years previously the diagnosis of von Hippel-Lindau (VHL)-syndrome has been established. Two years before a germ line mutation in exon 3 of the VHL-tumour suppressor gene has been detected. The patient has a healthy son with a normal VHL-gene and four healthy siblings who had refused a genetic blood test. INVESTIGATIONS: At abdominal ultrasound at the head of the pancreas three 4 2 cm large cysts and in the region of the left adrenal gland a 2,9 2,7 cm large tumor were visible. MRI of the abdomen revealed in addition a 2,2 1,5 cm large tumour of the right adrenal gland. An asymptomatic biadrenal phaeochromocytoma was detected by elevated urine catecholamines and 123I-MIBG-scintigraphy. TREATMENT AND COURSE: The cysts of the pancreas were punctured under endosonographical control and analysis of the cyst fluid was not suspicious of a malignant cystic tumour. The patient had no further abdominal complaints. After oral treatment with the alpha-blocker phentolamine the biadrenal phaeochromocytoma was treated by retroperitoneal laparoscopic surgery in an organ-sparing fashion. Postoperatively ACTH-stimulating test revealed a normal cortisol response. CONCLUSION: Adrenocortical function can be preserved by la-paroscopic adrenal-sparing surgery in bilateral phaeochromocytoma.

Journal Article↗

PubMed2001

Accuracy of the intra-operative radioguided localization of the sentinel lymph node (SLN) 24 hours after lymphoscintigraphy in patients with malignant melanoma.

AIM: For optimized logistics for the sentinel lymphadenectomy (SL) it might be helpful for the clinics involved if a longer time period between the lymphoscintigraphy (LS) and surgery is possible. Therefore, we investigated if a precise localization of the sentinel lymph node is possible 24 hours after LS. METHODS: 78 patients with primary malignant melanoma (MM; n = 44) or with MM pre-operated by excisional biopsy (n = 34) were investigated. In 40 cases the tumor was localized on the trunk and in 38 cases on the extremities. Mean MM thickness was 2.68 mm (range: 0.29 to 12 mm). In all patients a lymphoscintigraphy (LS) with an average of 85 MBq of Tc-99m nanocolloid was performed one day prior to surgery. Immediately after tracer application dynamic data acquisition was started at a LFOV gamma camera followed by a whole body scan. With a hand-held gamma detector (C-Trak) 2, 4, 6, 8, and 24 hours after tracer administration the SLN was identified and the counts registered. RESULTS: 94 SLNs were identified in 87 lymphatic basins from which 86 could be resected. Nine MM showed two draining channels. After 24 hours 15.5% (as an average) of the initial counts could be measured in the SLN. The uptake in the SLN in pre-operated versus patients with primary tumor was statistically not significant (p = 0.4). In 16 cases (20.5%) the SLN was tumor positive. Four of those patients developed distant metastases and two died within the first year. None of the patients with negative SLN developed distant metastases or died. CONCLUSION: The remaining activity in the SLN up to 24 hours after administration is sufficient for their intra operative localization. The method of lymphoscintigraphy and localization of the SLN by a hand-held gamma detector optimizes the intra operative identification of the SLN in patients with malignant melanoma.

Adult↗

PubMed2000

Preparation and biodistribution of rhenium-188 labeled albumin microspheres B 20: a promising new agent for radiotherapy.

Intra-arterial infusion of labeled particles is an effective method for endoradiotherapy of tumors. In this study, we radiolabeled biodegradable HSA microspheres (mean diameter = 25 microm) with the short-lived beta-emitter 188Re available from the aluminia-based 188W/188Re generator system. After 1 h 35-40% of the relative large amount of Sn(II) chloride required for effective reduction of Re(VII) for efficient attachment to the particles is precipitated as an amorphous coat of tin hydroxid colloid on the particle surface. The final 188Re bound to the particles was found to be stable in vitro. The radiolabelling yield was > 90%. The biological half-life was > 250 h and demonstrated sufficient in vivo stability after i.v. injection in Wistar rats. Because of the attractive properties of 188Re and the uniform particle size and stability, in vivo, this new agent is an attractive candidate for endoradiotherapy of tumors after selective catheterization.

Albumins↗

PubMed1999

[Changes in regional cerebral perfusion in depression.SPECT monitoring of response to treatment].

The objective of this study was to investigate the relationship between the effect of sleep deprivation, recovery and regional brain perfusion in patients with major depression. Regional cerebral blood flow was assessed by 99mTc-HMPAO-SPECT before and after sleep deprivation in fourteen medicated patients. Three of the patients underwent a follow-up measurement after clinical recovery and with an unchanged antidepressant medication. Before sleep deprivation the responding patients had a significantly higher anterior cingulate perfusion than the nonresponding patients, that normalized after sleep deprivation. Cingulate perfusion uniquely differentiated eventual treatment response from non-responders, as perfusion in no other region under study discriminated the two groups. At baseline all patients revealed hypoperfusion in the left prefrontal cortex when compared to the right side, which was not affected by sleep deprivation, whereas prefrontal hypoperfusion was reversible upon remission. These findings are in agreement with previous PET investigations and provide evidence for cingulate and prefrontal dysfunction associated with depression, that are reversible by successful treatment and may represent state markers.

Brain↗

PubMed1999

[Can immunoradiometric measurement of thyrotropin (TSH) in human serum compete with a luminometric assay?].

UNLABELLED: The development of highly sensitive, nonradioimmunometric assays for the measurement of thyrotropin (TSH) during the last few years have improved the measurement of low TSH values and thus benefit the diagnosis of thyroid function disorders. These third or fourth generation assays are especially popular in laboratories not accustomed to the use of radioactive tracers and can be easily automatized. AIM: This study investigates whether these new assays provide an advantage in routine diagnosis of thyroid disorders. METHODS: TSH was measured in 150 patients with various thyroid pathology using an immunoradiometric assay (IRMA) as well as a highly sensitive luminometric assay (LUMI), both by B.R.A.H.M.S. Diagnostica. We used the current modern IRMA (available since 1997) TSH was below 0.4 mU/l, between 0.4 and 4.0 mU/l, and above 4.0 mU/l in a third of the patients in each group, respectively. RESULTS: As expected the results obtained with LUMI and IRMA correlated well for TSH values above 0.1 mU/l and less well between 0.1 and 0.01 mU/l. There was no correlation between the two types of assay at TSH concentrations below 0.01 mU/l. This shows that measurements using both types of assay become increasingly less precise below 0.1 mU/l. CONCLUSION: Both types of assay gave an identical estimate of thyroid function in every single patient. Use of the LUMI did not give additional information leading to a change in patient management. Therefore, TSH measurement using IRMA does still meet today's routine clinical requirements.

Automation↗

PubMed1992

The hardware components of a computer system.

The two goals of this article are to give you a very brief overview of the evolution of computing and an introduction to the elements of a computer. The birth of the modern computer can be traced to John von Neumann. The model he proposed consisted of four major parts: the control unit, the arithmetic unit, the memory, and the input/output unit. His concept for a "stored program" computer provided the foundation for five decades of computer designs.

Computer Systems↗

PubMedDate not supplied

Chromogranin A: an additional tumor marker for postoperative recurrence and metastases of medullary thyroid carcinomas?

In this study, plasma concentrations of chromogranin A, calcitonin and carcinoembryonic antigen (CEA) were measured in 40 healthy volunteers as well as in 129 patients with recurrences and/or metastases of neuroendocrine tumors and of medullary thyroid carcinomas (MTCs). A double antibody assay was employed using polyclonal rabbit antibodies to a C-terminal fragment of the protein for detection of human chromogranin A. Using ROC analysis, a cutoff at 22 U/l chromogranin A was calculated. In patients with neuroendocrine tumours, much higher serum concentrations of chromogranin A than for patients with MTC (80% vs. 46%) were measured. The following sensitivities were found: chromogranin A; 46%, calcitonin 100%, CEA 52%. Furthermore, the mean values of chromogranin A concentrations correlated with the tumour mass and/or number of metastases in MTC and neuroendocrine tumours. Evaluation of follow-up studies remains to be completed; however, preliminary results showed similarities regarding the behaviour of chromogranin A and calcitonin. Despite the findings of this study, the observations could not confirm chromogranin A as a reliable marker for metastazing or recurrent MTC.

Biomarkers, Tumor↗