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S Diederich

Publications and source records attributed to S Diederich.

At least 91 records · Page 5Linked to original sources
PubMed1996

[HRCT of the lung in collagenoses].

Collagen vascular diseases, representing systemic soft tissue disorders, may cause a broad spectrum of pathologic changes of the respiratory tract. The type and extent of manifestations can vary considerably among individuals and entities. This survey describes the chest radiographic and, in particular, high-resolution computed tomographic (HRCT) findings of individual lesions of the respiratory tract. It includes fibrosing alveolitis (alveolitis, interstitial pneumonia, pulmonary fibrosis) and bronchial (bronchitis/bronchiolitis, bronchiectasis), pleural and vascular manifestations, as well as lymphadenopathy and abnormalities related to therapy. We present typical patterns of changes in progressive systemic sclerosis (PSS, scleroderma), systemic lupus erythematosus (SLE), mixed connective tissue disease (MCTD, Sharp syndrome), Sjögren syndrome, overlap syndrome and rheumatoid arthritis (RA). Furthermore, we describe findings which are specific for individual entities such as esophageal involvement in PSS, acute pneumonitis and pulmonary hemorrhage in SLE, lymphoproliferative disease in Sjögren syndrome and necrobiotic nodules in RA.

Arthritis, Rheumatoid↗
PubMed1996

The metabolism of 9 alpha-fluorinated steroids in the human kidney.

UNLABELLED: We compared the renal metabolism of 9 alpha-fluorinated steroids with that of the unfluorinated, endogenous steroid cortisol (F). By defining kinetic variables, we characterized isoenzyme activities of 11 beta-hydroxysteroid-dehydrogenase (11 beta-HSD). METHODS: I) In human kidney slices, we studied the conversion of 9 alpha-fluoro-cortisol (FF) and F to their oxo-products (and vice versa). II) In human kidney microsomes, we performed the kinetic analysis of 11 beta-HSD activity for the steroid pairs F/cortisone (E) and dexamethasone (D)/11-dehydro-dexamethasone (DH-D). RESULTS: I) In kidney slices, FF is very weakly oxidized to 9 alpha-fluorocortisone (FE), while the reduction of FE to FF is very effective. In contrast, E is hardly reduced to F, but F is strongly inactivated to E. II) Enzyme kinetics in kidney microsomes: 1a) Oxidation of F to E: exclusively NAD-dependent; K(m) = 25.5 nmol/L. b) Reduction of E to F: clearly NADH-preferring; K(m) = 81 nmol/L; Vmax(oxidation) /Vmax(reduction) (F/E) = 26.2a) Oxidation of Dtto DH-D: exclusively NAD-dependent; K(m) = 81 nmol/L b) Reduction of DH-D to D: exclusively NADH-dependent; K(m) = 68 nmol/L; Vmax(oxidation)/Vmax(reduction) (D/DH-D) = 0.09. Thus, the equilibrium of FF/FE in human kidney slices is far on the biologically active hydroxy-side. This shift, induced by the 9-fluorination, gives a good explanation for its mineralocorticoid potency. The cosubstrate dependence and the K(m)-value of the oxidation of F are similar to those of the cloned human 11 beta-HSD-II. For the first time, we could show a NADH-dependent reduction of E to F. Moreover, we found that the preference of D/DH-D for the reductase reaction (see the quotients Vmax(oxidation)/Vmax(reduction)) is due toaa NADH-dependent enzyme (probably 11 beta-HSD-II). These results provide strong evidence against the "dogma" of an "unidirectional" 11 beta-HSD-II.

11-beta-Hydroxysteroid Dehydrogenases↗
PubMed1996

Chronic sputum production: correlations between clinical features and findings on high resolution computed tomographic scanning of the chest.

BACKGROUND: There are few published data on the correlation between the clinical findings in subjects with chronic sputum production and the appearances on high resolution computed tomographic (HRCT) scans of the chest. METHODS: HRCT scanning of the chest was performed on 40 subjects with chronic sputum production. Three readers independently reported the scans for the presence or absence of bronchiectasis and the extent of bronchiectasis on the basis of the percentage of involved bronchi in each lobe. Relationships were sought between these findings and the clinical history, physical examination, and laboratory investigations. RESULTS: HRCT scanning showed that 27 subjects had bronchiectasis. Of the clinical features only the continual production of purulent sputum and childhood pertussis were associated with bronchiectasis. There was a positive correlation between the extent of bronchiectasis and dyspnoea, and a negative correlation with forced expiratory volume in one second but not with forced vital capacity. CONCLUSIONS: These results indicate that, in subjects with chronic sputum production, only a few clinical features show any correlation with the presence or extent of bronchiectasis as visualised on HRCT scans.

Adult↗
PubMed1996

Human kidney 11 beta-hydroxysteroid dehydrogenase: regulation by adrenocorticotropin?

In ectopic adrenocorticotropin (ACTH) syndrome (EAS) with higher ACTH levels than in pituitary Cushing's syndrome and during ACTH infusion, the ratio of cortisol to cortisone in plasma and urine is increased, suggesting inhibition of renal 11 beta-hydroxysteroid dehydrogenase (11 beta-HSD) by ACTH or by ACTH-dependent steroids. Measuring the conversion of cortisol to cortisone by human kidney slices under different conditions, we tested the possibility of 11 beta-HSD regulation by ACTH and corticosteroids. Slices prepared from unaffected parts of kidneys removed because of renal cell carcinoma were incubated with unlabeled or labeled cortisol, and cortisol and cortisone were quantitated after HPLC separation by UV or radioactive detection. The 11 beta HSD activity was not influenced by incubation with increasing concentrations (10(-12)-10(-9) mol/l) of ACTH (1-24 or 1-39) for 1 h. Among 12 ACTH-dependent steroids tested (10(-9)-10(-6) mol/l), only corticosterone (IC50 = 2 x 10(-7) mol/l), 18-OH-corticosterone and 11 beta-OH-androstenedione showed a significant dose-dependent inhibition of 11 beta-HSD activity. The percentage conversion rate of cortisol to cortisone was concentration dependent over the whole range of cortisol concentrations tested (10(-8) - 10(-5) mol/l. A direct inhibitory effect of ACTH on 11 beta-HSD is, therefore, unlikely. The only steroids inhibiting the conversion of cortisol to cortisone are natural substrates for 11 beta-HSD. Kinetic studies show a saturation of the enzyme at high cortisol concentrations. Thus, the reduced percentage renal cortisol inactivation in EAS seems to be due mainly to overload of the enzyme with endogenous substrates (cortisol, corticosterone and others) rather than to direct inhibition of 11 beta-HSD by ACTH or ACTH-dependent steroids, not being substrates of 11 beta-HSD.

11-beta-Hydroxysteroid Dehydrogenases↗
PubMed1994

[Radiological findings in lung transplantation].

Lung transplantation (single-lung transplantation, double-lung transplantation or heart-lung transplantation) may be the only effective therapy in end-stage pulmonary disease. At specialized institutions it has been performed on a routine basis for some years now. Diagnostic imaging plays an important role in the assessment of potential recipients as well as for the postoperative evaluation after transplantation. The aim of this review is to describe the role of imaging procedures of the chest in these patients and to demonstrate characteristic plain radiographic and computed tomographic findings. Normal postoperative findings specific to lung transplant patients as well as typical complications are presented. These include reimplantation response, acute and chronic rejection, and the typical bacterial, viral, and fungal infections as well as the sequelae of transbronchial biopsy.

Adult↗
PubMed1994

Impaired renal 11 beta-oxidation of 9 alpha-fluorocortisol: an explanation for its mineralocorticoid potency.

9 alpha-Fluorocortisol (9 alpha FF) is about 200 times more potent as a mineralocorticoid than cortisol (F) in man, although it binds with the same affinity as F and aldosterone to the human mineralocorticoid receptor. The low mineralocorticoid activity of F has been shown to be due to its rapid conversion by the kidney to cortisone (E), which does not bind to the receptor. Therefore, we compared the conversion of F to E with that of 9 alpha FF to 9 alpha-fluorocortisone (9 alpha FE) by 11-hydroxysteroid dehydrogenases in man in vivo and in vitro. Single oral doses of 9 alpha FF, 9 alpha FE, and F were given to normal males, and the excretion of free 9 alpha FF, 9 alpha FE, F, and E was measured in urine. Human kidney and liver slices were incubated with unlabeled steroids, and the free 11-hydroxy- and 11-oxosteroids were quantitated after high performance liquid chromatography separation by UV absorption. Oral F (5 mg) is excreted 70% as free E and 30% as free F (percentage of free steroids only). Oral 9 alpha FF (5 mg) is excreted 90% as free 9 alpha FF and 10% as free 9 alpha FE. Free 9 alpha FF excretion is 14 times greater than that of F after ingesting an identical dose. Oral 9 alpha FE (4 mg) is also excreted 90% as 9 alpha FF and 10% as 9 alpha FE. Kidney slices convert F much faster to E than 9 alpha FF to 9 alpha FE. The conversion of 9 alpha FE to 9 alpha FF is, on the contrary, much faster than that of E to F. Thus, the equilibrium of the reaction is on the 11-oxo side for F/E and on the 11-hydroxy side for 9 alpha FF/9 alpha FE. The interconversion of both pairs of steroids is inhibited by glycyrrhetinic acid in a dose-dependent manner. Liver slices do not measurably convert 9 alpha FF to 9 alpha FE, but do rapidly convert 9 alpha FE into 9 alpha FF. Reflecting this negligible conversion of 9 alpha FF to 9 alpha FE and the low plasma-protein binding of 9 alpha FF, free urinary 9 alpha FF excretion is much higher than that of F after the same oral dose.(ABSTRACT TRUNCATED AT 400 WORDS)

11-beta-Hydroxysteroid Dehydrogenases↗
PubMed1994

Sonographic features of mediastinal tumors.

Although mediastinal sonography, thus far, is used rarely in the United States, it might play a role in the diagnostic workup of mediastinal pathology as an adjunctive examination technique to other imaging studies (chest radiography, CT, and MR imaging). Mediastinal sonography is an effective and inexpensive imaging method, with a higher sensitivity than conventional radiographs, for the detection of mediastinal tumors [1-3]. The diagnostic advantage of mediastinal sonography over chest radiography results from its capability to demonstrate deep central mediastinal lymph nodes sonographically long before a displacement of pleuromediastinal lines occurs [3]. Mediastinal sonography is inferior only marginally to CT in the detection of supraaortic, pericardial, and prevascular lesions (sensitivity, 98-100%), but certain compartments (e.g., the posterior mediastinum and the paravertebral region) can be evaluated only with CT or MR imaging [3]. In addition to the assessment of size and topographic characteristics of mediastinal masses, sonography precisely visualizes the internal structure of the tumor, which may suggest a specific diagnosis when considered along with the clinical presentation and the location of the tumor [4]. This article illustrates the sonographic appearance of various mediastinal tumors.

Aortic Diseases↗
PubMed1993

[Pancreatic metastases: sonographic and computed tomographic findings].

We analysed sonographic (n = 19) and CT (n = 15) findings in 19 patients with intrapancreatic metastases (solitary: n = 8, multiple: n = 11) from solid tumours. The diagnosis was confirmed either histologically (n = 5) or by the follow-up showing decrease of the size of the lesion due to chemotherapy (n = 3) or progression without specific therapy (n = 11). Clinically or serologically organ-related symptoms were found in 5 cases, whereas the rest of the patients were free of symptoms. Sonographically the metastases appeared hypoechogeneic compared to normal pancreatic parenchyma. In 15 cases CT at the time of sonographic investigation demonstrated hypodense intrapancreatic lesions (8/15) or bulging of the organ contour without differences in density (2/15). In some patients (5/15) sonographically detected metastases measuring less than 2 cm were not discovered via CT. In a patient with known malignancy multiple intrapancreatic lesions must be considered as metastases. Differential diagnosis includes diffusely growing pancreatic carcinoma, haemorrhagic necrotising pancreatitis and focal infiltrates due to malignant lymphoma.

Adult↗
PubMed1993

[Postmortem high-resolution computed tomography of the lung. Radiologic-morphologic correlations].

To establish precise correlations between high-resolution computed tomography (CT) and normal pulmonary anatomy and pulmonary pathology, 49 lungs affected by different diseases were analysed. Post-mortem high-resolution CT scans were compared with the corresponding macroscopic and microscopic pathological findings. For scanning, lungs were inflated and fixed, which avoided any decrease in the structural resolution of pulmonary parenchyma and allowed a topographically exact correlation between CT appearances and morphological changes. After demonstration of the structural details relevant for CT in normal pulmonary parenchyma, an attempt is made to establish the morphological basis of the following CT phenomena: thickening of interlobular septae, increase in pulmonary translucency, consolidation of the non-nodular alveolar and of the nodular type, and changes in the pleural region. Although CT findings in pulmonary lesions are mainly non-specific, knowledge of the corresponding morphological basis is helpful in diagnostic evaluation.

Animals↗
PubMed1993

[Computed tomography in noninfectious interstitial lung diseases].

Computed tomography is a well-established imaging technique for the assessment of non-infectious interstitial pulmonary disease. Compared with the conventional chest radiograph it is characterized by a higher degree of sensitivity and specificity, particularly when a high-resolution technique is implemented. Because of its superior correlation with the morphological characteristics in specific diseases, it plays an important role if the histological diagnosis is doubtful and also in patients with clinical features suggestive of pulmonary disease in the presence of a normal chest film. This article describes the limitations of the conventional chest radiograph and the advantages of pulmonary computed tomography. Typical CT findings in different interstitial diseases are illustrated, and their value is discussed in comparison with the plain radiograph.

Asbestosis↗
PubMed1992

Diagnosis and therapy surveillance in Addison's disease: rapid adrenocorticotropin (ACTH) test and measurement of plasma ACTH, renin activity, and aldosterone.

The rapid ACTH injection test is an indirect screening test for adrenocortical insufficiency. As a supplement to this test, we evaluated the practicability of single measurements of plasma cortisol, ACTH, aldosterone, and PRA as a definitive diagnostic test of primary adrenocortical insufficiency (PAI). We also tested the value of PRA measurements during treatment with hydro- and fludrocortisone (HC and FC) as a guide for correct mineralocorticoid substitution. In 45 patients with PAI, results of the rapid ACTH test and single measurements of the four hormones (all tests between 0800-0900 h) were compared. Single hormone measurements were also made in 55 normal subjects and 46 patients with pituitary disease (cortisol and ACTH only), most of them with mild to severe secondary adrenocortical insufficiency (SAI). The rapid ACTH test was abnormal in 100% of 41 patients with PAI tested. Plasma ACTH, PRA, and the ratios of ACTH/cortisol and PRA/plasma or urinary aldosterone were clearly elevated in 100% of the patients with PAI. The ACTH/cortisol ratio also distinguished 100% of patients with PAI from those with SAI, but not always control subjects from those with SAI. Thus, dynamic tests (CRH or insulin tests) are indicated if SAI is suspected. PAI and involvement of zona fasciculata and glomerulosa function can be diagnosed with high reliability by measuring cortisol, ACTH, aldosterone, and PRA either together with the rapid ACTH test or later, after a short interval of steroid substitution. PRA measurements during treatment with HC and FC correlated better with the mineralocorticoid dose than plasma potassium and sodium levels. PRA measurement is a valuable guide for FC replacement therapy. It should be titrated into the upper normal range to avoid under- and overtreatment.

Addison Disease↗