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Biomedical subjects

Stefan K Grebe

Publications and source records attributed to Stefan K Grebe.

5 recordsLinked to original sources
PubMed2006

Molecular diagnosis of a BRAF papillary thyroid carcinoma with multiple chromosome abnormalities and rare adrenal and hypothalamic metastases.

OBJECTIVE: Molecular characterization of thyroid tumors is rarely applied to patient management. Our aim was to demonstrate the application of molecular and cell biology to patient care. DESIGN: Clinical and molecular case study. MAIN OUTCOMES: A 57-year-old man with papillary thyroid carcinoma presented with adrenal and several other presumed metastases, pulmonary nodules, and mediastinal lymphadenopathy. Bronchial carcinoma was entertained for the pulmonary lesions because of a tobacco history. Mediastinal lymph node biopsy was nondiagnostic. Cells from the biopsy were grown in tissue culture and characterized by immunocytochemical (ICC), allele-specific polymerase chain reaction (PCR), reverse transcription (RT)-PCR, DNA sequencing, and cytogenetics. A panel of agents were tested the cells for tumoricidal activity. The cells expressed thyroid-specific markers [thyroid-stimulating hormone receptor (TSH-R), thyroglobulin (TG), sodium iodide symporter (NIS)] and markers [thyroid transcription factor-1 (TTF-1), cytokeratin-7, epidermal growth factor receptor (EGF-R)] present in the primary tumor and adrenal metastasis. The BRAF V600E mutation was detected. The karyotype was 44-48,XY, + der(1) t(1;9)(p13;p13),add(9)(p13),-17,-18, + 0-3mar[cp20]. Lovastatin, gefitinib, paclitaxel, depsipeptide, and 17-AAG inhibited the growth of the cultured cells. Combinations of two or three drugs produced additive or synergistic effects depending upon the combination. CONCLUSIONS: Unusual metastases may be associated with multiple molecular and cytogenetic abnormalities. Thus, molecular and cell-biological studies can allow otherwise difficult thyroid tumor diagnosis and may be used for targeted, individualized selection of potential treatments.

Adrenal Gland Neoplasms↗
PubMed2004

Quantitative, highly sensitive liquid chromatography-tandem mass spectrometry method for detection of synthetic corticosteroids.

BACKGROUND: Measurements of serum or urine concentrations of synthetic glucocorticoids are useful for assessing suspected iatrogenic hypothalamic-pituitary-adrenal axis suppression and Cushing syndrome. We have developed a liquid chromatography-tandem mass spectrometry (LC-MS/MS) assay for the simultaneous quantitative analysis of beclomethasone dipropionate, betamethasone, budesonide, dexamethasone, fludrocortisone, flunisolide, fluorometholone, fluticasone propionate, megestrol acetate, methylprednisolone, prednisolone, prednisone, triamcinolone, and triamcinolone acetonide. METHODS: Stable isotopes of cortisol-9,11,12,12-d(4) and triamcinolone-d(1) acetonide-d(6) were added as internal standards to calibrators, controls, and unknown samples. After acetonitrile precipitation, these samples were extracted with methylene chloride, and the extracts were washed and dried. Reconstituted extract (15 muL) was injected on a reversed-phase column and analyzed by LC-MS/MS in positive-ion mode. Assay precision, accuracy, linearity, and sample stability were determined by use of enriched samples. Clinical validation included analysis of 8 serum and 20 urine samples from patients with undetectable cortisol concentrations and analysis of different types of tablets. RESULTS: Functional assay sensitivity was as low as 0.6-1.6 nmol/L for all compounds except for triamcinolone (7.6 nmol/L). Interassay CVs were 3.0-20% for concentrations of 0.6-364 nmol/L for all analytes. Recoveries of all analytes (except triamcinolone in serum) were 82-138% at 19.2-693 nmol/L. All but one of the serum and urine samples from patients who were tested because of suppressed cortisol concentrations contained at least one synthetic steroid. Tablet analysis recovered 75% of the synthetic steroids in suspected drugs. CONCLUSIONS: LC-MS/MS allows simultaneous quantitative detection of various synthetic steroids in serum, plasma, urine, and tablets. This provides a valuable tool for evaluating the clinical effects of topical and systemic synthetic corticosteroids.

Adrenal Cortex Hormones↗
PubMed2003

Liquid chromatography-tandem mass spectrometry assay for simultaneous measurement of estradiol and estrone in human plasma.

BACKGROUND: Estradiol (E2) and estrone (E1) measurements form an integral part of the assessment of female reproductive function and have expanding roles in other fields. However, many E1 and E2 immunoassays have limited functional sensitivity, suffer from cross-reactivity, and display poor intermethod agreement. To overcome these problems, we developed a sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) assay for the simultaneous measurement of E1 and E2. METHODS: After dansyl chloride derivatization, samples were separated by fast gradient chromatography and injected into a tandem mass spectrometer after formation of positive ions with atmospheric pressure chemical ionization. The limits of detection and quantification, recovery, linearity, precision, and reference intervals were determined, and performance was compared with several immunoassays. RESULTS: Total run time per sample was 5 min. The multiple-reaction monitoring ion pairs were m/z 506/171 for 3-dansyl-estradiol and m/z 504/171 for 3-dansyl-estrone. The limits of detection for E1 and E2 were 12.9 pmol/L (3.5 ng/L) and 10.3 pmol/L (2.8 ng/L), respectively. Interassay imprecision (CV) was 4-20% (n = 20). The limits of quantification (functional sensitivities) for E1 and E2 were 44.1 pmol/L (11.9 ng/L) and 23.2 pmol/L (6.3 ng/L), respectively. The assay was linear to >2200 pmol/L ( approximately 600 ng/L) for each analyte. Recoveries were 93-108% for E1 and 100-110% for E2. No cross-reactivity was observed. Method comparison with several immunoassays revealed that the latter were inaccurate and prone to interferences at low E1 and E2 concentrations. CONCLUSIONS: LC-MS/MS allows rapid, simultaneous, sensitive, and accurate quantification of E1 and E2 in human serum.

Adult↗