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Biomedical subjects

Ricardo V Lloyd

Publications and source records attributed to Ricardo V Lloyd.

At least 19 recordsLinked to original sources

Immunohistochemical expression of nestin in the non-tumorous hypophysis and in pituitary neoplasms.

The aim of the present work was to investigate whether nestin, a member of the intermediate filament family, is immunohistochemically expressed in the non-tumoral human hypophysis and pituitary neoplasms. Twenty-three normal pituitaries and 125 pituitary neoplasms were included. The tissues were formalin-fixed and paraffin embedded. The neoplasms were identified on hematoxylin-eosin stained sections and were classified by immunohistochemistry as well as electron microscopy. For immunohistochemistry, the streptavidin-biotin-peroxidase complex method was applied using appropriate controls. Several corticotrophs in the autopsy obtained pituitaries showed cytoplasmic nestin immunopositivity. No nestin immunoreactivity was found in other cell types in non-tumorous adenohypophyses and in the cells of various pituitary adenomas. Nestin was, however, expressed in a small proportion of endothelial cells in both anterior and posterior lobes. Staining was also noted in several pituicytes, neurohypophysial nerve fibers, and Herring bodies. In contrast to CD-34 and Factor-8 immunostaining which demonstrated immunopositivity in practically all endothelial cells of every capillary, nestin expression was only focally seen suggesting that the functional status of the immunoreactive and non-staining endothelial cells was not the same. No statistically significant correlation was apparent between nestin immunoreactivity and patient age, gender, tumor size, mitotic index, Ki-67, labeling nuclear index, hormonal immunoprofile, and tumor type. In conclusion, nestin expression in adenomas cannot be viewed as a biologically relevant marker of cell proliferation and as a prognostic indicator. The patchy expression of nestin in endothelial cells remains unexplained and its significance requires further studies.

Adenoma↗

Modulation of VEGF/Flk-1 receptor expression in the rat pituitary GH3 cell line by growth factors.

Both vascular endothelial growth factor (VEGF) and its receptor Flk-1 are expressed in normal pituitary cells and in the prolactin- and growth hormone-producing GH3 cell line of the rat, thus suggesting autocrine/paracrine function. Regulation of the Flk-1 receptor system in pituitary cells is poorly understood, but evidence suggests that up-regulated growth factors play a role in its expression and activation. To study the role of growth factors in this process, we examined changes in VEGF and Flk-1 expression in GH3 cells following varied exposure to betaFGF, EGF, and TGFbeta1. Immunofluorescence labelling and laser scanning cytometry were used to measure changes in VEGF and Flk-1 expression. Results showed that betaFGF, EGF and TGFbeta up-regulated the VEGF/FLK-1 receptor system. Distinct patterns of activation were detected. At 2 hours, EGF and TGFbeta caused no significant changes in VEGF and Flk-1 expression; however, betaFGF up-regulated VEGF expression in 99% of cells but only induced modest changes in Flk-1 overexpression. A similar percentage of cells overexpressed VEGF after 24-hour incubation with betaFGF, but more prominent Flk-1 overexpression was detected. At 24 hours, EGF and TGFbeta1 induced a significant increase in both VEGF and Flk-1 expression. In summary, our findings show that VEGF/Flk-1 expression in pituitary cells may be altered by different growth factors. This may affect angiogenesis and the progression of pituitary tumors.

Animals↗

BRAF mutation analysis in fine needle aspiration (FNA) cytology of the thyroid.

BRAF mutations have been detected in 30% to 80% of papillary thyroid carcinomas (PTC). Several detection methods for BRAF mutation have been reported, but a direct comparison between different assay methods has not been previously reported. In this study, we examined the diagnostic utility of BRAF (T1799A) mutation in 71 cases of thyroid fine needle aspiration specimens using 4 different methods, including direct sequencing, Colorimetric Mutector Assay, real-time LightCycler polymerase chain reaction (LC PCR) with fluorescence resonance energy transfer probes, and an allele-specific LC PCR with CYBR green 1. BRAF mutation was detected in 31 of 58 cases of PTC, but not in 13 cases of non-PTC lesions. The 4 assay methods used in this study were sensitive, reliable, and comparable with each other (100% of specificity and 53.5% of sensitivity). PTC harboring BRAF mutation had higher extrathyroidal invasion and/or lymph node metastasis than PTC with wild-type BRAF. BRAF mutation analysis should be useful for the clinical diagnosis of PTC in cases of indeterminate fine needle aspiration specimen, because of the high degree of specificity. Our results indicate that there is similar sensitivity for the four detection methods. However, the allele-specific LC PCR with CYBR green 1 method is most rapid, easier to perform, and least expensive technique, and it can be readily performed in most molecular diagnostic laboratories.

Adult↗

Vascularization of rat pituitary autografts.

Pituitary autotransplantation eliminates direct vascular contact between the hypothalamus and the adenohypophysis, and enables us to study the role of the hypothalamus in regulating adenohypophysial endocrine activity. The aim of this study was to investigate vascularization of the pituitary autografts. Three-month-old male Wistar rats were hypophysectomized, and their adenohypophyses were autotransplanted under the renal capsule. The animals were killed 3 weeks after autotransplantation. The grafts were removed and studied by using histology, immunohistochemistry and transmission electron microscopy. In the central portion of the grafts, organizing necrosis was apparent. The peripheral portion of the graft contained all adenohypophysial cell types, with a predominance of lactotrophs. Vascular endothelial growth factor and hypoxia-inducible factor were expressed in the graft mainly in the perinecrotic areas. Several capillaries inside the grafts were lined by continuous unfenestrated epithelium, while others were lined by fenestrated endothelium, suggesting that neovascularization is the result of two processes: ingrowths of capillaries from the renal capsule to the graft, and neoformation of capillaries from pre-existing adenohypophysial vessels. In conclusion, hypoxia seems to be an important factor in the vascularization of pituitary autografts. Mediated via hypoxia-inducible factor, hypoxia stimulates vascular endothelial growth factor secretion, which plays a crucial role in angiogenesis.

Animals↗

Pathobiology of pituitary adenomas and carcinomas.

OBJECTIVE: To examine relationships between pituitary tumors and lesion size, invasiveness, resectability, deoxyribonucleic acid ploidy, cell cycle profile, mitotic activity, and immunoreactivity for MIB-1, proliferating cell nuclear antigen (PCNA), p27Kip1, and p53. PATIENTS AND METHODS: One hundred fifty-three adenomas of most pathological subtypes, including 20 medically treated and prolactin and growth hormone-containing tumors, as well as 10 premetastatic tumors and 13 pituitary carcinomas, were studied. RESULTS: Significant (P < 0.05) differences were noted between functional versus nonfunctional adenomas (percent aneuploidy, percent S phase, p27Kip1 labeling indices [LI], male sex, tumor size, and frequency of visual disturbance); Cushing's versus silent adrenocorticotropin adenomas (percent hypertetraploidy, p53 LI, tumor size, visual disturbance, and resectability); untreated versus medically treated prolactin cell adenomas (MIB-1 LI, p53 LI, and resectability); untreated versus medically treated growth hormone-containing adenomas (percent diploidy, percent S phase, MIB-1 LI, p53 LI, and p27 LI); untreated prolactin cell adenomas versus premetastatic tumors (percent hypertetraploidy, PCNA LI, p53 LI, invasiveness, and resectability); untreated growth hormone-containing adenomas versus premetastatic tumors (percent diploidy, percent S phase, PCNA LI, p53 LI, invasiveness, and resectability); Cushing's adenomas versus premetastatic tumors (percent diploidy, percent hypertetraploidy, percent S phase, MIB-1 LI, p53 LI, tumor size, invasiveness, visual disturbance, and resectability); Nelson's adenomas versus premetastatic tumors (p53 LI, tumor size, invasiveness, and resectability); silent adenomas as a whole versus nonfunctional adenomas (percent nondiploid, percent S phase, invasiveness, and respectability); silent adrenocorticotropin adenomas I and II versus silent adenoma Subtype III (invasiveness); silent adrenocorticotropin adenoma Subtypes I and II versus premetastatic tumors (MIB-1 LI and invasiveness); silent adenoma Subtype III versus premetastatic tumors (PCNA and p53 LI); and premetastatic tumors versus metastatic pituitary carcinomas (MIB-1 LI). CONCLUSION: Only trends toward differences were noted between Cushing's versus Nelson's adenomas and between prolactinomas of reproductive female patients versus those of menopausal female patients and male patients. Too few "atypical adenomas" were encountered to permit their comparison with premetastatic tumors, but our results suggest that most pituitary carcinomas arise by malignant transformation from adenomas.

Adolescent↗

Patterns of gene expression in pituitary carcinomas and adenomas analyzed by high-density oligonucleotide arrays, reverse transcriptase-quantitative PCR, and protein expression.

Very few of the genes that are important in pituitary tumor initiation, progression, and metastasis have been identified to date. To identify potential genes that may be important in pituitary tumor progression and carcinoma development, we used Affymetrix GeneChip HGU-133A-oligonucleotide arrays, which contain more than 15,000 characterized genes from the human genome to study gene expression in an ACTH pituitary carcinoma metastatic to the liver and four pituitary adenomas. Reverse-transcriptase real-time quantitative- PCR (RT-qPCR) was then used to analyze 4 nonneoplastic pituitaries, 19 adenomas, and the ACTH carcinoma. A larger series of pituitary adenomas and carcinomas were also analyzed for protein expression using tissue microarrays (TMA) (n = 233) and by Western blotting (n = 18). There were 4298 genes that were differentially expressed among the adenomas compared to the carcinoma, with 2057 genes overexpressed and 2241 genes underexpressed in the adenomas. The beta-galactoside binding protein galactin-3 was underexpressed in some adenomas compared to the carcinomas. Prolactin (PRL) and ACTH tumors had the highest levels of expression of galectin-3. The human achaetescute homolog-1 ASCL1 (hASH-1) gene was also underexpressed in some adenomas compared to the carcinoma. Prolactin and ACTH tumors had the highest levels of expression of hASH-1. ID2, which has an important role in cell development and tumorigenesis, was underexpressed in some adenomas compared to the carcinomas. Transducin-like enhancer of split four/ Groucho (TLE-4) was over-expressed in adenomas compared to the ACTH carcinoma. The differential expression of these genes was validated by RT-qPCR, by immunohistochemistry using TMA and by Western blotting. These results indicate that the LGALS3, hASH1, ID2, and TLE-4 genes may have important roles in the development of pituitary carcinomas.

ACTH-Secreting Pituitary Adenoma↗

Morphologic changes of prolactin-producing pituitary adenomas after short treatment with dopamine agonists.

Treatment of patients with prolactin (PRL)-producing pituitary adenomas with dopamine agonists has proved successful for most cases. Dopamine agonists inhibit PRL secretion, suppress cell proliferation, and may induce apoptosis to adenoma cells. Dopamine agonists induce striking morphologic changes in the majority of treated PRL-producing adenomas. To date, these morphologic effects have been primarily described only after long-term treatment. To the best of our knowledge, no similar studies have investigated apoptotic alterations induced after short-term therapy. The purpose of this report is to describe the morphologic changes seen in PRL-producing adenomas after short-term dopamine agonist treatment. We present two cases of PRL-producing macroadenomas, both from male patients who received treatment with dopamine agonists, the first for 5 and the second for 8 days. In contrast to long-term treatment, no striking reduction of PRL immunoreactivity was noted. Slight stromal fibrosis was noted in case 1, which contained several cells all in late phase of apoptosis. In addition to typical apoptotic cells, numerous "dark" cells representing another common form of cell death were also noted. These novel findings represent characteristic features of short-term dopamine agonist treatment, which are not seen in long-term treatment.

Adult↗

Induction of GH, PRL, and TSH beta mRNA by transfection of Pit-1 in a human pituitary adenoma-derived cell line.

The functional development of pituitary cells depends on the expression of a combination of transcription factors and co-factors. Pituitary-specific transcription factor-1 (Pit-1) is required for the expression of growth hormone (GH), prolactin (PRL), and the thyroid-stimulating hormone beta subunit (TSH beta) and acts synergistically with the estrogen receptor (ER) and GATA-binding protein 2 (GATA-2) to induce PRL and TSH beta expression, respectively. The glycoprotein hormone alpha subunit (alpha SU) is the first hormone to be expressed during pituitary development. In addition to being expressed in follicle-stimulating hormone, luteinizing hormone (LH), and TSH cells, alpha SU is reported to co-localize with GH in pituitary cells. These findings have led to the suggestion that the expression of Pit-1 in cells of the alpha SU-based gonadotropin cell lineage might also lead to the expression of GH. In this study, we transfected HP 75 cells (derived from a human non-functioning pituitary adenoma that expressed alpha SU and LH beta) with Pit-1 by using an adenovirus FLAG-Pit-1 construct. Most of the transfected cells expressed GH mRNA, with fewer cells expressing PRL and TSH beta mRNA. The HP 75 cells expressed the genes for ER and GATA-2, thus allowing their expression of GH, PRL, and TSH beta mRNA in response to Pit-1. These results support the hypothesis that GH can be induced in cells that possess an active alpha SU gene and shed light on the basic molecular mechanism that drives the development of GH, PRL, and TSH beta expression in the alpha SU-based gonadotroph lineage.

Adenoma↗

Hyperinsulinemic hypoglycemia with nesidioblastosis after gastric-bypass surgery.

We describe six patients (five women and one man; median age, 47 years; range, 39 to 54) with postprandial symptoms of neuroglycopenia owing to endogenous hyperinsulinemic hypoglycemia after Roux-en-Y gastric bypass surgery. Except for equivocal evidence in one patient, there was no radiologic evidence of insulinoma. Selective arterial calcium-stimulation tests, positive in each patient, were used to guide partial pancreatectomy. Nesidioblastosis was identified in resected specimens from each patient, and multiple insulinomas were identified in one. Hypoglycemic symptoms diminished postoperatively. We speculate that hyperfunction of pancreatic islets did not lead to obesity but that beta-cell trophic factors may have increased as a result of gastric bypass.

Adult↗

Effects of DNA methylation on galectin-3 expression in pituitary tumors.

Galectin-3 (Gal-3), a beta-galactoside-binding protein is expressed in a specific cell-type manner in pituitary tumors. Here we questioned the mechanism of Gal-3 expression in pituitary tumors, by using methylation-specific PCR and DNA sequence analyses to analyze the methylation status of the promoter region of the LGALS3 gene. DNA analysis of a human pituitary tumor, breast carcinoma cell lines, and thyroid carcinoma cell lines showed that in cells expressing Gal-3 protein, the LGALS3 gene was unmethylated, whereas in Gal-3 null cells, the promoter of the LGALS3 gene was methylated. Treatment of cells with 30 mumol/L 5-aza-2'-deoxycytidine induced Gal-3 mRNA and protein expression. Among pituitary tumors, 30% (7/23), mainly in follicle-stimulating hormone/luteinizing hormone-producing (38%) and null cell (57%) adenomas, the promoter of the LGALS3 was found to be methylated and silenced, although prolactin- and adrenocorticotropic hormone-producing tumors, which were unmethylated, expressed the Gal-3 protein. These results show for the first time that Gal-3 expression is regulated in part by promoter methylation in pituitary as well as in other tumors. Because it is functionally involved in cancer progression and metastasis, Gal-3 may serve as a possible therapeutic target in the treatment of pituitary tumors.

Adenoma↗

RASSF1A and NORE1A methylation and BRAFV600E mutations in thyroid tumors.

We analyzed RASSF1A and NORE1A methylation and BRAF mutation in 89 thyroid tumors, 42 non-neoplastic thyroid tissues and three thyroid tumor cell lines using polymerase chain reaction (PCR), methylation-specific PCR, Western blotting and DNA sequencing in order to study thyroid tumor pathogenesis and progression. RASSF1A promoter methylation was present in all three thyroid cell lines and in 27/78 (35%) of benign and malignant thyroid tumors. We showed for the first time that there was generally good agreement between RASSF1A methylation status and RASSF1A protein expression. We also examined for the first time NORE1A promoter region methylation in thyroid cell lines and primary tumors and showed that two of three thyroid cell lines were methylated in the NORE1A promoter region, while all primary thyroid tumors analyzed (n=51) were unmethylated. BRAF mutation was present in 38% of papillary thyroid carcinomas (PTC), including 20% of PTC with a follicular variant pattern and 67% of the tall cell variant of PTC. Hyalinizing trabecular tumors (n=23), which had nuclear features similar to PTC, did not have BRAF mutations, indicating that the presence of BRAF mutations can help to separate these two tumor types. Phospho-MEK expression was increased in the NPA cell line, which had a BRAF mutation, supporting the importance of the BRAF pathway alterations in PTC pathogenesis. These results indicate that RASSF1A epigenetic changes are an early event in thyroid tumor pathogenesis and progression and that NORE1A methylation is uncommon in primary thyroid tumors. BRAF mutation occurs later in thyroid tumor progression and is restricted mainly to PTC and anaplastic thyroid carcinoma.

Adaptor Proteins, Signal Transducing↗

Role of COX-2, thromboxane A2 synthase, and prostaglandin I2 synthase in papillary thyroid carcinoma growth.

The development of papillary thyroid carcinoma is influenced by many factors including genetic alterations, growth factors, and physical agents such as radiation. Arachidonic acid and its derivatives including prostaglandins (PG) and thromboxane along with the enzymes involved in their synthesis have been shown to influence the growth of various tumors. We analyzed the immunoreactivity for cyclooxygenase-2 (COX-2) and mRNA expression levels of the enzymes COX-2, thromboxane A(2) (TXA(2)) synthase, and PGI(2) synthase by RT-PCR in papillary carcinomas and matching normal tissues to determine the role of these enzymes in the development of papillary thyroid carcinomas. A papillary thyroid carcinoma cell line TPC-1 was also studied in vitro to determine the role of the specific COX-2 inhibitor NS-398 on COX-2 and vascular endothelial growth factor-A, since COX-2 also has a role in regulating tumor angiogenesis. RT-PCR analysis showed significant increases in TXA(2) synthase mRNA levels in papillary thyroid carcinomas compared to normal thyroid tissues. Although COX-2 mRNA levels were generally increased in papillary carcinomas, the differences were not statistically significant. There were no significant differences in PGI(2) synthase mRNA levels. COX-2 protein expression was greater in papillary carcinoma compared to normal thyroid tissues; however, the levels were quite variable. In vitro studies with a COX-2 inhibitor, NS-398, showed inhibition of tumor growth along with increased levels of COX-2 and vascular endothelial growth factor-A mRNA expression. These results indicate that specific enzyme levels in the PG synthesis pathway such as TXA(2) synthase are increased in papillary thyroid carcinomas. COX-2 also has a role in papillary thyroid growth, since a specific inhibitor of COX-2 regulates papillary thyroid carcinoma cell proliferation. These results implicate several enzymes in the synthesis of prostanoids as regulators of thyroid papillary carcinoma proliferation and suggest that increased levels of expression of these enzymes may play a role in the pathogenesis of these tumors.

Adult↗

Epidermal growth factor receptor and activated epidermal growth factor receptor expression in gastrointestinal carcinoids and pancreatic endocrine carcinomas.

The epidermal growth factor receptor (EGFR) plays an important role in the pathogenesis of many tumors. To analyze the expression of EGFR and activated EGFR in well-differentiated neuroendocrine carcinomas including primary and metastatic gastrointestinal carcinoid tumors and pancreatic endocrine tumors (PET), we examined 58 gastrointestinal carcinoid tumors and 48 PET using immunohistochemistry, Western blotting, and RT-PCR. EGFR and activated EGFR (P-EGFR) were expressed by both gastrointestinal carcinoids and PET in primary and metastatic tumors, although a higher percentage of gastrointestinal carcinoid tumors expressed EGFR and activated EGFR. Western blotting detected a 170 kDa band for both EGFR and activated EGFR in three primary carcinoid tumors and two metastatic carcinoid tumors to the liver. RT-PCR analysis confirmed the expression of EGFR mRNA in both primary and metastatic carcinoid tumors. Patients with activated EGFR expression in their primary PET had a significantly worse prognosis compared to those who did not express activated-EGFR (P = 0.043). These results indicate that gastrointestinal carcinoid tumors as well as PET express EGFR and activated EGFR, and that expression is more common in gastrointestinal carcinoid tumors compared to pancreatic endocrine tumors. These findings implicate the EGFR and P-EGFR signal transduction pathway in the pathogenesis of these neuroendocrine tumors and suggest that targeted therapy directed against the EGFR tyrosine kinase domain may be a useful therapeutic approach in patients with unresectable metastatic gastrointestinal carcinoid tumors and pancreatic endocrine tumors.

Blotting, Western↗

Diagnosis of cat scratch disease with Bartonella henselae infection in formalin-fixed paraffin-embedded tissues by two different PCR assays.

Cat scratch disease (CSD) is commonly caused by Bartonella henselae infection. Clinical history and histologic findings are often insufficient to establish a definitive diagnosis of CSD. We retrospectively studied formalin-fixed, paraffin-embedded (FFPE) lymph nodes from 35 patients with histologically suspected CSD by 2 different PCR assays and immunohistochemistry (IHC). The first primer pair amplified a 163-bp fragment of the 16S rRNA gene in 19 of the 35 cases (54%). The second primer pair amplified a 191-bp fragment of the henselae citrate synthase (gltA) gene in 17 of the 35 cases (49%). IHC identified the organisms in 8 of 33 cases (24%). Fresh cultures of various Bartonella species showed a specific PCR product with an analytical sensitivity of 0.5 to 5 pg bacterial DNA. Bartonella species were identified by the unique size of the amplified PCR product. Twenty-two lymph nodes without morphologic evidence or a history of CSD were negative by PCR and immunostaining. Tissues from a patient with Legionella pneumophila were also negative by PCR and immunostaining for CSD supporting the specificity of the PCR reaction. The specific PCR products of the B. henselae were confirmed by sequencing. Human beta-actin for each case was amplified to check the integrity of the DNA. Our data indicate that detection of Bartonella DNA by PCR is useful to confirm the diagnosis of CSD.

Actins↗

Molecular diagnosis of Ewing's sarcoma/primitive neuroectodermal tumor in formalin-fixed paraffin-embedded tissues by RT-PCR and fluorescence in situ hybridization.

Recent studies have suggested that formalin-fixed paraffin-embedded (FFPE) tissues can be used for molecular analyses by fluorescence in situ hybridization (FISH) and RT-PCR. We analyzed 18 cases of ES/PNET for the t(11;22)(q24;q12) and t(21;22)(q22;q12) fusion transcripts by RT-PCR and analyzed for EWS translocation by interphase FISH with a dual color fusion probe to compare these two approaches directly. RT-PCR detected 13 (72%) EWS-FLI-1 fusions (type I=10, type II=3) and 2 (11%) EWS-ERG fusions. Three cases could not be evaluated because the housekeeping gene phosphoglycerate kinase (internal mRNA control) was not amplified. FISH was diagnostic in 15 of 18 cases (83%). There were three discordant cases between RT-PCR and FISH (concordance of 83%). Using a combination of RT-PCR and FISH, the results were complementary. One advantage of RT-PCR analysis was that subtypes of EWS translocation could be determined specifically (type I, type II and ERG). These findings indicate that because of the difficulties and limitations associated with the molecular analysis of FFPE tissues, a combination of RT-PCR and FISH may be a better approach to enhance the sensitivity and accuracy of detecting ES/PNET translocations in FFPE tissues with suboptimally preserved nucleic acids.

Base Sequence↗

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↗

DNA microarrays: recent developments and applications to the study of pituitary tissues.

Many new techniques are rapidly being developed and applied to the study of normal and neoplastic pituitary. DNA microarrays are a uniquely efficient method for simultaneously assessing the expression levels of thousands of genes, identifying disease subphenotypes, and predicting disease progression. This article reviews the utility of DNA microarray-based tumor profiling including recent developments and applications to pituitary biology in order to demonstrate how these new techniques are providing insights about basic aspects, clinical knowledge, and pharmacologic knowledge of the pituitary gland and about pituitary tumors.

Adenoma↗