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Biomedical subjects

H Hundeshagen

Publications and source records attributed to H Hundeshagen.

At least 19 recordsLinked to original sources
PubMed1992

Limitations of clearance determination using the single sample distribution volume method. An error analysis on the basis of compartment models.

To investigate the error possibly contained in the single sample distribution volume method for the determination of renal clearance, a mathematical model was applied to describe the effect of changes in distribution volume, clearance, intravascular space, intracompartmental exchange and the time point of blood sampling. The method was found to be valid only under well-defined circumstances (Topt = 45 +/- 5 min, Cl = 390 +/- 50 ml/min, Vd = 16.7 +/- 4 l, alpha = 0.05.V1 ml/min, V1/Vd = 0.5 +/- 0.05) as shown in sample calculations. Two-compartment model-based error calculations demonstrate that this technique implies at best an uncertainty of +/- 10% or more. Whilst it can be used preferably in healthy, normal-weight adults, it is not applicable, without error, under all other circumstances.

Humans↗
PubMed1992

[Trans-sternal cervico-mediastinal primary tumor resection and lymphadenectomy in thyroid gland cancer].

Thyroid carcinoma may invade the mediastinum by direct extension of the primary tumor or metastases to the paratracheal or retroclavicular-parajugular lymph nodes. From 1975 to 1991 in 47 out of 622 thyroid cancer patients (7.6%) [14 papillary (PTC), 5 follicular (FTC), 16 medullary (MTC) and 12 undifferentiated carcinoma (UTC)] transsternal tumor resection has been performed. Four patients (UTC three, MTC one) deceased 7, 8, 35, and 41 days after resection of the primary tumor due to cardiac or tumor disease, and in one patient because of acute arteriotracheal haemorrhage after external irradiation; no patient deceased after transsternal resection as a result of cervicomediastinal lymphadenectomy. At the time of primary operation 80% of patients showed an advanced tumor stage (greater than pT3). In 34% of patients (PTC 64%, FTC 40%, MTC 13%, UTC 25%) no tumor recurrence was observed neither by imaging nor by biochemical methods. In 18 patients a transsternal microdissection of all four cervicomediastinal lymph node compartments has been performed. Histological analyses of excised and tumor involved lymph nodes revealed in 9 patients unilateral cervical and mediastinal and in 9 patients bilateral cervical and mediastinal lymph node metastases. In the case of unilateral cervicomediastinal lymph node metastases 2 out of 2 patients with papillary and 2 out of 6 patients with medullary thyroid carcinoma could be cured surgically. In the case of bilateral cervicomediastinal lymph node metastases 3 out of 4 patients with papillary thyroid carcinoma, but no other thyroid cancer patient were free of disease. In conclusion, main indications for transsternal cervicomediastinal resection in thyroid carcinoma are (1) primary tumors extending to the upper mediastinum, but without lymph node metastases, and (2) thyroid carcinomas with unilateral cervicomediastinal lymph node metastases. In the case of bilateral cervicomediastinal lymph node metastases probable only papillary thyroid carcinomas are supposed to be curable by transsternal multicompartmentectomy.

Adenocarcinoma↗
PubMed1992

[The clinical course of oxyphilic carcinoma of the thyroid].

In a total of 1665 patients with malignant thyroid neoplasms 90 oxyphilic thyroid carcinomas (OTC) were found of whom 55 could be re-examined and newly classified. Morphological and clinical parameters influencing the clinical course were determined. During a mean follow-up period of 6.5 y metastases or local recurrent disease occurred in 12 patients (24%). Apart from 3 early manifestations of metastases, 9 patients developed recurrent disease within, on average, 4.7 y after thyroidectomy: local lymph node metastases and local recurrences occurred within an average of 5.4 y, distant metastases after only 2.7 y. Thyroglobulin proved to be reliable for follow-up with a sensitivity of 88% on levothyroxine and 75% on endogenous TSH-stimulation (specificity: 98%). The frequency of metastases and local recurrences correlated with age at the time of tumor diagnosis, the degree of invasiveness and the local tumor extension (pT4 vs. pT1-3), whereas other factors such as the absolute diameter of the tumor or patient's sex had no influence on the clinical course. The survival probability for 5 and 10 years was 95 and 75%, respectively. All OTC patients should be examined regularly at least once a year by cervical sonography and thyroglobulin measurement. Because 18% recurrences occurred within 4.7 y such examinations should be repeated beyond year 5 after thyroidectomy.

Aged↗
PubMed1992

[Mucociliary clearance in childhood].

AIM OF THE STUDY: A new, nearly monodisperse human serum albumin particle produced by air-pressure-nebulization was inhaled by children and lung-transplant patients. METHOD: After inhalation of the particles obtained with an air-pressure nebulizer, the initial deposition pattern showed a marked tracheobronchial deposition which could be reproducibly obtained without a special breathing technique, the alveolar deposition being not higher than 10%. With the use of 99mTc, the radiation exposure is limited to a level which is low enough for children, but images can be taken up to 24 hrs later. Further parameters for in vivo characterization of the mucociliary function are the 24 h retention pattern and the velocity of particle motion in the trachea. RESULTS: Within the first 45 minutes, the global clearance rate was 51% in healthy children, which is rather high in comparison with the literature, most likely due to size of particles and the selection of patients with a mean age of 10.7 years. In ciliary dysfunction, the initial clearance rate was 16% and 46% within 24 h. CONCLUSIONS: With simplification of the preparation, application, and examination technique, this method is to be used in children, so that a wider use can be anticipated. The normally fast initial elimination of particles allows quick differentiation of normal and impaired ciliary function.

Adolescent↗
PubMed1991

[The effect of magnetic resonance treatment on chicken embryos].

Nuclear Magnetic Resonance (NMR) is of increasing diagnostic importance especially in human medicine. To evaluate possible side effects of this technology, embryonated chicken eggs were used as a model. Different fields (static magnetic field [1 oder 4 T], variable magnetic field [gradient] or high frequency field) were applied before the beginning and at the fifth day of incubation for different times (18.8, 37.6, 56 or 75.1 min, resp.). According to the criteria embryo-mortality, hatching-rate or vitality of the chickens, influences of the NMR-treatment were not observed.

Animals↗
PubMed1990

Imaging of dialysis-related amyloid (AB-amyloid) deposits with 131I-beta 2-microglobulin.

The diagnosis of dialysis-related amyloid (AB-amyloid) has been based usually on clinical and radiological criteria. Following the discovery that beta 2-microglobulin was the major protein of this amyloid, we isolated and radiolabelled uremic plasma beta 2-microglobulin. After intravenous injection, gamma-camera images of selected joint areas were obtained from 42 patients who were on regular hemodialysis therapy. Positive scans involving the shoulder, hip, knee and carpal regions were found in 13 of 14 patients treated for more than 10 years and 10 of 16 patients treated for 5 to 10 years. Patients treated for less time had negative scans. Specificity was indicated by negative scans in non-amyloid inflammatory lesions in control hemodialysis patients. Up to 48-fold tracer enrichment was detected in excised AB-amyloid containing tissue as compared to amyloid-free tissue. These findings suggest that circulating radiolabelled beta 2-microglobulin is taken up by the amyloid deposits. This method may non-invasively detect tissue infiltrates of amyloid. It may also permit prospective evaluation of the efficacy of prophylactic dialysis strategies which are designed to prevent or delay the onset of this complication of long-term dialysis.

Amyloidosis↗
PubMed1990

Positron emission tomography in neuropsychiatric lupus erythematosus.

We performed positron emission tomography (PET) using 18F-labeled 2-F-2-deoxyglucose in 13 patients with systemic lupus erythematosus (SLE). Ten of them had clinical signs of central nervous system involvement (NP-SLE). All patients with neurologic symptoms showed pathologic changes on PET, always in accordance with the clinical state. Three patients without neuropsychiatric manifestations had normal PETs. Computed tomography of the brain and magnetic resonance imaging proved to be less sensitive to both presence and localization of CNS lesions. We conclude that the combination of PET and MRI constitutes the most useful diagnostic procedure for NP-SLE.

Adolescent↗
PubMed1990

[A comparison of two algorithms for determining renal whole body clearance following simultaneous acquisition with a partially shielded whole-body counter and a gamma camera].

The influence of instrumentation, algorithm, and the time of blood sampling on whole-body renal clearance as defined by effective renal plasma flow (ERPF) was investigated. The study involved simultaneous sampling with a partially shielded whole-body counter (WBC) and a gamma camera to assess ERPF. The results obtained using two different analysis algorithms for each modality are compared. Although ERPF as determined by the Oberhausen technique was significantly higher than that obtained using an algorithm developed by the authors, for each algorithm there was no significant difference between the WBC and gamma camera-derived values within the range of 100 to 800 ml/min. Furthermore, positioning of the ROI was not critical for gamma camera-derived ERPF (SD less than 1% for multiple crescentic ROIs and approximately 4% for multiple rectangular ROIs). However, the time of blood sampling did appear more important since the average ERPF derived from the 10- and 20-min samples compared with that from the 15- and 25-min samples differed significantly for both analysis algorithms. The methodology which we have validated provides a more precise tool for further investigations of the influence of medication, posture, and exercise stress on renal function.

Algorithms↗
PubMed1990

[Clinical and magnetic resonance imaging follow-ups of children after dilatation of aortic isthmus stenosis (CoA)].

Aortic aneurysm and stenosis are the most severe post-interventional complications after angioplasty of CoA and require regular follow-up. Twenty children (4 2/12-13 11/12 years old) underwent MRI within 3 months to 5 7/12 years after dilatation. All children were in a good state of health and showed no signs of heart failure. Three patients suffered from arterial hypertension; seven children showed hypertension on exertion. In six children, a resting gradient (minimal 20 mm Hg, maximal 40 mm Hg) between the upper and lower extremities could be measured. Four children showed pathological changes of the ascending aorta, three had a moderate ectasia, one had severe dilatation of more than 5 cm in diameter. In three cases, a circumscript aneurysm of the descending aorta was found. In many cases, there were mild changes in the aortic wall in the region of dilatation. In 12 children, there was a moderate spindly dilatation distal to the aortic isthmus, which, however, could be seen in the pre-dilatation angiography. After dilatation of CoA, several patients continue to have hypertension and pathological changes of the thoracic aorta. With regard to adequate therapy, regular controls are necessary. Besides routine examinations, MRI is an effective non invasive imaging method for the initial investigation and short-time follow-up evaluation of CoA.

Adolescent↗
PubMed1989

PET and MR imaging in a neuro-Behçet syndrome.

Positron emission tomography (PET) and magnetic resonance imaging (MRI) studies were performed on a case of neuro-Behçet's syndrome. In accordance with the clinical signs, FDG PET (using 18F-labeled 2-F-2'-desoxyglucose) revealed disseminated storage defects in the cerebrum and cerebellum. Focal regions of enhanced signal intensity were demonstrated in the parietal white matter of the cerebrum in T2-weighted images and in the brain stem by MRI.

Adult↗
PubMed1989

Specific imaging of dialysis-related amyloid deposits using 131I-beta-2-microglobulin.

Dialysis-related amyloidosis (DRA), characterized by its association with beta 2-microglobulin (beta 2m), has become a major concern in long-term hemodialysis patients. Hitherto the diagnosis was based on histological examinations of tissue obtained by biopsy or during surgery. In this preliminary study a new noninvasive diagnostic method was developed using the affinity of beta 2m for its derived fibrils. 3 patients on long-term hemodialysis for 10-16 years with biopsy-proven DRA and 1 patient on chronic hemodialysis for only 6 months were examined after intravenous injection of 131I-labelled beta 2m. Specific local accumulation of radioactivity was noted in the DRA patients after 48 h, persisting for further 96 h and corresponding to clinically or radiologically evident sites of amyloid deposition and to several other hitherto unsuspected sites. Examination of an excised amyloid tumor subsequent to in vivo labelling confirmed a highly specific accumulation of radioactivity in the amyloid tissue but not in control tissue. In the patient on chronic hemodialysis for only 6 months, no specific local accumulation was detected even after 1 week. These findings provide in vivo evidence in man that a specific uptake of circulating amyloid precursor molecules into deposits occurs and that this uptake may be used to radiolabel even small tissue infiltrates of amyloid. This method therefore may not only allow an objective, noninvasive detection of DRA but may also be used to obtain new pathophysiologic insights into amyloid formation in man, as well as permitting the evaluation of preventive therapeutic strategies in prospective studies on new patients.

Amyloidosis↗