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Biomedical subjects

G Kontogeorgos

Publications and source records attributed to G Kontogeorgos.

At least 55 records · Page 3Linked to original sources
PubMed1991

Multiple adenomas of the human pituitary. A retrospective autopsy study with clinical implications.

In a review of autopsy material from two centers, 20 pituitary glands were found containing multiple adenomas. In total, 44 adenomas were identified histologically; 16 glands contained double tumors and in four glands triple adenomas were found. Size was measured in 30 tumors, all of which were microadenomas. Thirty-four adenomas were located in the lateral wings and 10 lay in the median wedge. Forty-one tumors were chromophobic and three were basophilic. Immunocytochemical analysis of the 44 tumors demonstrated the presence of prolactin in 11, adrenocorticotropic hormone in three, growth hormone in one, and alpha-subunit as well as follicle-stimulating hormone and luteinizing hormone in one. Of the 20 patients studied, there were 11 men and nine women, with an average age of 69 years. All patients died from various nonendocrine causes. With the exception of one patient who appeared mildly acromegalic, no correlation was observed between pituitary morphology and clinical data. This study found a 10.4% frequency of adenomas in pituitaries studied randomly at autopsy. Multiple tumors were encountered in 0.9% of cases. Despite its low frequency, adenoma multiplicity may underlie surgical failure in cases in which one adenoma is removed and the other is left behind.

Adenoma↗
PubMed1991

Alpha-subunit immunoreactivity in plurihormonal pituitary adenomas of patients with acromegaly.

Twelve plurihormonal pituitary adenomas, removed surgically from 11 of 20 patients with acromegaly, were investigated. The mean age of the 11 patients was 45 yr. Seven patients with eight tumors were men. The tumors were immunostained for all known adenohypophysial hormones by the avidin-biotin-peroxidase complex (ABC) technique. All 12 adenomas were immunoreactive for growth hormone (GH) and alpha-subunit; prolactin (PRL) was detected in five tumors. Stains for the beta-subunits of glycoprotein hormones [thyroid-stimulating hormone (TSH), follicle-stimulating hormone (FSH), and luteinizing hormone (LH)] revealed immunopositivity for specific beta-subunits in ten adenomas. The close association between GH and alpha-subunit in pituitary tumors of acromegalic patients remains to be explained.

Acromegaly↗
PubMed1991

Null cell adenoma of the pituitary with features of plurihormonality and plurimorphous differentiation.

The case of a 35-year-old man with pituitary macroadenoma who was complaining of reduced sexual activity is presented. Histologic examination showed a chromophobic adenoma corresponding mainly to a null cell adenoma at the ultrastructural level. Focal plurihormonality and plurimorphous differentiation of adenoma cells were demonstrated by immunohistochemical and electron-microscopic studies. It is suggested that adenomatous null cells represent pluripotent progenitor cells capable of transforming to different hormone-producing cell types. The factors accounting for differentiating to various cell populations have yet to be elucidated.

Adenoma↗
PubMed1990

ERG and electron microscopic findings after intravitreal use of aminoglycosides.

The electroretinographic (ERG) changes and the retinal lesions shown by electron microscopy were studied in rabbits after intravitreal use of amikacin and tobramycin. We studied 40 eyes of 20 rabbits in which different doses ranging from 250 micrograms to 1000 micrograms of aminoglycosides were injected into the vitreous cavity. Tobramycin, and to some extent amikacin, were toxic to the retina even in doses of 500 micrograms as shown by ERG changes. The pathologic retinal lesions shown by electron microscopy were characterized by membranous inclusions in the retinal pigment epithelium, tumefaction of the photoreceptors, and partial disorganization of the inner layers. In doses of 250 micrograms or less, these two antibiotics seem to be nontoxic after a follow-up of three months.

Amikacin↗
PubMed1988

S-100 protein and neuron specific enolase (NSE) expression by chordomas in relation to the composition of their stromal mucosubstances.

The immunoreactivity of S-100 protein and neuron specific enolase (NSE.) was correlated with the composition of stromal glycosaminoglycans in chordomas and human notochords, in a combined histochemical and immunohistochemical study. We found that S-100 protein is negative in notochordal and chordoma cells in the absence of stromal mucosubstances or in the presence of small quantities of hyaluronic acid. The positivity of S-100 immunoreaction was found to be related to the presence of stromal glycosaminoglycans of the chondroitine sulfate A and C type. NSE. was found positive in cells presenting features of high metabolic activity. Consequently S-100 protein and NSE. immunoreactivity cannot have any cytogenetic implications, but they could be considered as markers indicating specific cell-stromal functional interactions.

Chordoma↗
PubMed1986

Tubal conjoined twin pregnancy.

A unique case of tubal conjoined twin pregnancy is reported. The embryos presented a lateral type of conjunction, which also is extremely rare, and were classified as symmetrical iliothroacopagus conjoined twins.

Adult↗
PubMed1985

A histological and immunoenzymatic study on the histogenesis of "giant cell tumor of bones".

We carried out a prospective histologic and immunoenzymatic study, using lysozyme and AI-antichymotrypsin, of 15 well documented cases of giant cell tumors of bones. The histologic appearance of the majority of the tumors was characterized by great pleomorphism. The predominant histologic patterns could be classified as either fibroblastic or histiocytic. Mitoses were seen exclusively on stromal mononuclear cells. All tumors showed positive marking with both lysozyme and AI-antichymotrypsin. The enzymatic activity was more pronounced in areas of conventional histology and appeared as coarse orange-brown granules in the cytoplasm of many mononuclear and multinucleated giant cells. Enzyme-positive cells were less frequently found in fibroblastic areas of the tumor and especially in areas with minimal differentiation. The results indicate that giant cell tumor of bones may result from the neoplastic proliferation of mononuclear cells which in many areas of the tumor differentiate to either fibroblasts or histiocytes. Thus, giant cell tumor of bones may be analogous to fibrohistiocytic tumors of soft tissues.

Adult↗
PubMed1984

Microcalcifications in breast carcinomas. A histological and histochemical study.

Microcalcification in breast carcinomas were studied histologically and histochemically in 332 prospectively collected mastectomy consecutive specimens, without previous roentgenographic examination. Microcalcifications were found in 41% of breast carcinomas. The incidence was higher in comedo-carcinomas, duct carcinomas nonotherwise specified (N. O. S.) and papillary carcinomas. In situ and infiltrative lobular carcinomas did not show any microcalcification. Histochemically, calcium was shown to be deposited in compound lipids. The morphology and localization of microcalcifications was similar to those described in fibrocystic disease. This should be ascribed to similar structural and cellular conditions in both diseases.

Breast Neoplasms↗
PubMed1984

Microcalcifications in benign breast diseases. A histological and histochemical study.

A hundred cases of fibroadenomas and 300 cases of benign breast diseases were studied without previous roentgenographic examination of the specimens. Microcalcifications were found in 19% of the fibroadenomas, in 26% of the cases of "fibrous disease" and in 57% of the cases of fibrocystic disease. Benign microcalcifications were not found in normal mammary tissue. They were steadily associated with metaplastic epithelial cells and with their abnormal secretions. Two basic types of microcalcifications were encountered: The granular microcalcifications with a predominately intracellular location and the homogeneous (with or without concentric rings) mainly associated with secreted materials. Microcalcifications were associated with metaplastic epithelial cells of the small eosinophilic variety and with their secretions, with the foam cells and with materials secreted by the apocrine cells. A common histochemical feature in cells or matrixes containing microcalcifications was the presence of compound lipids. The possible relationship of benign breast microcalcifications to the calcifications of other tissues, in connection with their association with lipids is discussed.

Adenofibroma↗
PubMed1983

Mucous metaplasia of epithelial cells in fibrocystic disease of the breast. A histochemical study.

Mucous metaplasia of breast epithelium was studied by histochemical procedures in cases of fibrocystic disease. Epithelial mucins consist almost entirely of non-sulfated sialomucins. A slight amount of sulfated sialomucins was identified occasionally while neutral mucins seems to be absent. Abundant glycogen granules are contained in the cytoplasm of metaplastic cells. The secretion of sialomucins may be associated with a loss of cell antigenicity. In this case, the survival of metaplastic epithelium supports the hypothesis of the possible immunological nature of the disease.

Epithelium↗
PubMed1979

Duct elastosis in infiltrating carcinoma of the breast.

Duct elastosis was studied in 219 patients subjected to radical mastectomy for infiltrating carcinoma of the breast, with a 10-year follow-up. Duct elastosis is a frequent finding in infiltrating breast cancer (65% of our cases). It develops in tumors of all three grades of malignancy, but it is more frequent in tumors of low grade malignancy (76% and 74% in grades I and II, respectively, and 47% in grade III tumors). In spite of their greater incidence in low malignancy tumors, the elastotic cases have a greater metastatic ratio than the non-elastotic cases (66% vs 45%). The elastotic cases also contain a significantly greater proportion of scirrhous tumors than the non-elastotic cases (86% vs. 32%). Duct elastosis and scirrhous reaction are two processes which develop in parallel, but are not related etiologically. They seem to be correlated with more advanced stages of the neoplastic disease. The influence of duct elastosis upon the ten year survival of the patients is unfavorable. this influence is not direct, and it is particularly evident in the metastatic cases. It seems to be related to the greater duration of the neoplastic disease and to the slow clinical course of tumors of low degree of malignancy.

Breast Neoplasms↗
PubMed1978

Chondrosarcoma of the larynx.

We report one case of chondrosarcoma of the larynx, which is considered to be rather uncommon. Clinical signs and symptoms have been noted, as well as some suggestions on the aetiology, incidence and site of cartliaginous tumours of the larynx.

Aged↗
PubMed1978

Diagnostic and therapeutic difficulties of leucoplakia of the renal pelvis.

2 cases of leucoplakia of the renal pelvis are reported. In the first one the diagnosis was established after nephrectomy and histological examination of the specimen. In the second one it was suspected on urine examination and was confirmed on histology. The current aspects about its cause and the difficulties concerning its diagnosis and treatment are discussed.

Aged↗
PubMedDate not supplied

Ultrastructural features of apoptosis in human pituitary adenomas.

Although several recent studies deal with various molecular aspects of apoptosis, or programmed cell death, very little information is available on the ultrastructural changes associated with apoptosis in the adenohypophysis and its role in the regulation of pituitary adenoma growth and progression. This paper describes the distinct ultrastructural sequences that develop during the various phases of the apoptotic process. The study is based on the ultrastructural investigation of more than 8,000 surgically removed pituitary biopsies, which were examined by histology and immunocytochemistry for diagnostic purposes. No apoptosis was found in normal adenohypophysis and it is also a rare event in pituitary adenomas. When present, adenomatous adenohypophysial cells exhibit common and characteristic apoptotic changes. The ultrastructural alterations of membraneous organelles associated with apoptosis are similar to those previously reported in other tissues. It is noteworthy that apoptosis is clearly distinguishable from the ubiquitous dark cells denoting the common way of cell death. The findings suggest that apoptosis in pituitary adenomas is not a random event. Practically every specimen containing multiple apoptotic cells represents corticotroph adenoma. Occasional examples occur in lactotroph or gonadotroph adenomas. Although electron microscopic specimens are admittedly small, the large number of investigated cases gives credence to the observations.

Adenoma↗
PubMedDate not supplied

Pituitary adenoma in Carney complex: an immunohistochemical, ultrastructural, and immunoelectron microscopic study.

First described in 1985, Carney complex is a rare, heritable disorder featuring abnormal skin pigmentation, cardiac and cutaneous myxoma, melanotic schwannoma of psammomatous type, and endocrine abnormalities, including pituitary adenomas. Patients with the latter present with elevated growth hormone (GH) levels and acromegaly or gigantism. Prolactin (PRL) elevation may also be seen. The authors have investigated 2 resected pituitary adenomas from patients with Carney complex. One, a 19-year-old female acromegalic with elevated GH, IgF-1, and PRL levels, had a mammosomatotroph adenoma immunoreactive for GH and PRL. Ultrastructurally, GH and PRL were present in the same secretory granules. The second patient, a 27-year-old acromegalic, had a sparsely granulated GH cell adenoma that by immuno-electron microscopy revealed GH immunoreactivity only. The lack of morphologic similarity between the 2 adenomas indicatesthat pituitary tumors in patients with Carney complex may not exhibit the same phenotype.

Abnormalities, Multiple↗
PubMedDate not supplied

Recent aspects in the diagnosis and prognosis of bladder cancer.

Epidemiologic studies have stated the progressive increase of bladder tumors during the last decades. The aim of our review is to refer to factors implicated in bladder carcinogenesis (such as activated oncogenes, growth factors and chromosomal aberrations) and to resistance to drug uptake (i.e., multidrug resistance gene and P-glycoprotein). The review also provides information of diagnostic and prognostic significance, based on DNA analysis of transitional cancer cells. In addition to cytometric data, alternative counterings for estimation of the S-phase fraction, useful in indicating the biologic behavior of bladder cancer, are presented. Knowledge of such mechanisms results in a better approach to the diagnosis, prognosis and prevention of bladder carcinomas, especially those that do not respond to systemic intravesical chemotherapy. We have tried to mention all significant factors related to the development of bladder cancer. We conclude that the progress made in understanding the pathogenesis of bladder cancer has been significant. However, more studies are needed in order to introduce and adopt reliable criteria to accurately predict the clinical behavior.

ATP Binding Cassette Transporter, Subfamily B, Mem↗