Biomedical subjects

Katharina Ruebel

Publications and source records attributed to Katharina Ruebel.

3 recordsLinked to original sources

PubMed2005

Analysis of pituitary cells by laser capture microdissection.

The anterior pituitary gland consists of a heterogeneous population of various cell types. To study a single cell type with a homogeneous cell population, one can perform laser capture microdissection (LCM). Because different pituitary cells have unique immunophenotypic profiles, it is possible to perform immunohistochemical staining before LCM (immuno-LCM) for the collection of a phenotypically homogeneous cell population. These techniques were developed and applied to dissociated anterior pituitary cells and cultured pituitary cells. When combined with reverse transcriptase polymerase chain reaction, it is possible to analyze gene expression in as few as one to 10 pituitary cells. We have used the immuno-LCM technique to prepare homogeneous populations of folliculostellate cells. These cells were analyzed for expression of peptides and receptors. Anterior pituitary hormones were not expressed by these cells. These results show the utility of immuno-LCM for cellular and molecular studies of gene expression.

Animals↗

PubMed2005

Galectin-3 Expression in Functioning and Silent ACTH-Producing Adenomas.

Galectin-3 (Gal-3), a beta galactoside-binding protein, has been implicated in a variety of biological functions including cell growth, differentiation, tumor cell adhesion, angiogenesis, tumor progression, and metastasis. We recently reported that Gal-3 was expressed in a subset of normal pituitary cells and tumors including PRL, ACTH, and in folliculo-stellate (FS) cells and tumors and that Gal-3 had an important regulatory role in pituitary cell proliferation. We further investigated the expression of Gal-3 protein in ACTH- and PRL-producing tumors and the expression of various galectin mRNAs by RT-PCR in pituitary adenomas and normal pituitary. Most silent ACTH subtypes 1 and 2 adenomas were negative or only focally positive for Gal-3 expression compared to functioning ACTH tumors from patients with Cushing's disease and Nelson's syndrome. In the normal pituitary, Gal-3 was expressed in less than 1% of the basophil-invading cells (ACTH cells present in the posterior pituitary) and in a subset of the anterior lobe ACTH-positive cells. RT-PCR analyses showed that many members of the galectin family including galectins 1, 2, 3, 4, 5, 6, 7, 8, and 9 were expressed in normal pituitary and in functioning ACTH- and PRL-producing tumors. These results indicate that Gal-3 is associated with functioning ACTH and PRL tumors and is expressed infrequently in silent ACTH adenomas, suggesting that Gal-3 protein and/or gene is altered in non-functioning ACTH tumors. The use of ACTH and Gal-3 immunostaining should help in the diagnosis of silent ACTH adenomas.

ACTH-Secreting Pituitary Adenoma↗

PubMed2003

Androgen receptor expression in C-cells and in medullary thyroid carcinoma.

Recent studies have shown a higher incidence of C-cell hyperplasia (CCH) in men compared with women in postmortem thyroid tissues. We postulated that the expression of androgen receptor (AR) protein may, in part, explain the differences. To test this hypothesis, we examined thyroid tissue from 27 consecutive autopsy cases for the presence of CCH (defined as >50 C-cells/x100 magnification in three fields) and for AR expression in autopsy cases and in 43 medullary thyroid carcinomas (MTCs) from patients with sporadic and familial disease as well as two multiple endocrine neoplasia type 2A patients with only CCH. CCH was present in 8 of 20 males (40%) and in 1 of 7 females (14%) at autopsy. AR protein was detected in most surgically resected thyroids with MTC and CCH (80%), but in only 25% of autopsy thyroids, probably reflecting postmortem degradation of the receptor protein. Reverse transcriptase polymerase chain reaction confirmed the presence of AR mRNA in MTC and in papillary thyroid carcinomas. These results support the observation that CCH is more common in postmortem thyroids of males and suggest that the presence of AR with higher circulating levels of androgens may contribute to the higher incidence of CCH in men.

Aged↗