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G Seifert

Publications and source records attributed to G Seifert.

At least 55 records · Page 3Linked to original sources
PubMed1997

[Diagnosis of cytomegalovirus disease in biopsy and surgical material. Methods and clinical relevance].

Since the first description of cytomegaly as "disease with protozoan-like cells" more than 50 years have past until a definitive explanation of the viral aetiology was reached. In the eighties cytomegaly gained increasing importance in adults. This event was based upon the occurrence of cytomegaly especially in patients with organ transplantation, AIDS infection, chronic dialysis or chemotherapy of malignant tumours. With the development of immunohistochemistry (IHC), in situ hybridization (IHS) and polymerase chain reaction (PCR) new, more sensitive methods became available to detect CMV infections especially in biopsy specimens or cytological material. With IHC, ISH and PCR CMV verification is possible in seemingly normal cells without inclusion bodies. PCR can be used also on small biopsy particles of paraffin-embedded material and is characterized by high specificity and sensitivity. The parallel performance of IHC and ISH was proved to be useful in routine diagnostic work, whereas PCR should be used especially in diagnostically different cases. The methods of the evidence of CMV infection are analysed in the different organs.

AIDS-Related Opportunistic Infections↗
PubMed1997

[Carcinoma in pre-existing Warthin tumors (cystadenolymphoma) of the parotid gland. Classification, pathogenesis and differential diagnosis].

Malignant transformation of pre-existing Warthin tumours of the parotid gland in carcinomas is very rare compared with the development of carcinomas in pre-existing pleomorphic adenomas. Five cases examined in the Salivary Gland Register of Hamburg 1965-1996 were classified in 2 cases as mucoepidermoid carcinoma and in each of one case as oncocytic carcinoma, squamous cell carcinoma and acinic cell carcinoma. In the pathogenesis the benign oncocytic epithelial formations at the surface of the cystic spaces are restricted by malignant neoplastic epithelial cells in the course of which transitions of squamous cell metaplasia or goblet cell metaplasia can be observed. In the further course an infiltrating spread of the carcinoma takes place into the lymphoid stromal component of the Warthin tumour, sometimes also an infiltration of the surrounding tissue und rarely to cervical lymph node metastases. The own findings are analysed concerning the classification of the carcinomas and the differential diagnosis under consideration of the until now reported cases of the literature.

Adenolymphoma↗
PubMed1997

[Sclerosing polycystic sialadenopathy. A rare non-tumorous disease].

Tumour-like lesions of the salivary glands are diseases which, in accordance with the new WHO classification of salivary gland tumours, can simulate a true tumour by swelling or induration of the salivary gland tissue. An additional rare entity, only recently not described in the new WHO classification, is "sclerosing polycystic sialadenopathy" (s.p.s.) which, especially in younger patients, results in nodular, incompletely encapsulated, tumour-like masses mainly of the parotid gland. Histologically, it is comparable to fibrocystic mastopathy and is characterized by distinct hyalinized, centrally accentuated sclerosing collageneous tissue with inclusion of cystically ectatic ducts and focal epithelial hyperplasia. In the hyperplastic ducts, trans-luminal bridges and cribriform patterns can develop, sometimes also apocrine secretion and eosinophilic globules. The s.p.s. must be distinguished mainly from cystadenoma, mucoepidermoid carcinoma and also from dysgenetic cystic parotid gland. Based on four of our own observations the differential diagnosis is analysed.

Adolescent↗
PubMed1997

[Heterotopic (extraosseous) calcification (calcinosis). Etiology, pathogenesis and clinical importance].

Heterotopic tissue calcification represents a pathological event which goes along with active extra- and intracellular metabolic processes. The heterotopic calcification is not the manifestation of tissue ageing. Aetiologically, metastatic calcification, dystrophic calcification and genetic-hereditary calcification are distinguished. Two pathogenetic mechanisms play a role during the heterotopic calcification. The intracellular calcification is based upon the function of mitochondria as regulator of the calcium concentration and as "lime-catcher". The extracellular calcification is initiated by membraneous organelles--so-called matrix vesicles. The further steps are the production of hydroxylapatite crystals which are eliminated from the matrix vesicles in the extracellular spaces. Special types of heterotopic calcification are hypercalcaemias (tumour-associated hypercalcaemias, primary and tertiary hyperparathyroidism, drug-induced hypercalcaemias), tumoral calcinosis, intratumoral calcifications, calcifications of different organs (lung, heart, vessels, joints, ligaments, skin or kidney). Some calcifications of organs show partly overlapping aetiological factors and pathogenetic mechanisms.

Aging↗
PubMed1997

AMPA receptor subunits expressed by single astrocytes in the juvenile mouse hippocampus.

The subunit composition of native AMPA receptor (AMPA-R) channels was recently described in several neuronal cell types but less information is available on glial cells. Evidence from recombinant receptor studies suggests that the expression of distinct subunits determines the specific functional properties of the receptor channel. In the present study, we combined the patch clamp technique with the reverse transcription-polymerase chain reaction (RT-PCR) to correlate the expression of gene transcripts with functional properties of AMPA-R in single identified glial cells of the hippocampus. The cells were freshly isolated from the stratum radiatum of the CA1 subregion. We focused on cells expressing AMPA-R with an intermediate Ca2+ permeability which were identified as immature astrocytes due to their morphological, immunocytochemical and electrophysiological characteristics. After recording, the cells were harvested and RT-PCR was performed with the same individual cell to investigate the composition of their AMPA-R transcripts. Our results suggest the expression of a heteromeric subunit architecture. In all cells, the GluR2 subunit was present, which is known to confer a low Ca2+ permeability to the receptor complex. Most frequently, we met co-expression of GluR2 and GluR4. This study demonstrates that astrocytes in the hippocampus express a distinct AMPA-R subunit composition which differs from neurons. The glial receptors might be involved in the modulation of gene expression as well as the regulation of proliferation and differentiation.

Animals↗
PubMed1997

Tumour-simulating squamous cell metaplasia (SCM) in necrotic areas of salivary gland tumours.

Squamous cell metaplasia (SCM) adjacent to necrotic areas of salivary gland tumours must be distinguished from other types of SCM (focal SCM in the excretory ducts of salivary glands; necrotizing sialometaplasia; focal SCM within salivary gland tumours) in respect to the tissue structure. Based on the high cellular proliferation, arcade- or cord-like pseudoneoplastic SCM develops with stellate extension in the surrounding tissue and focal inclusion of goblet cell metaplasia. This proliferative SCM resembles the cellular demarcation of radicular dental cysts. In the Salivary Gland Register 8 cases of tumor-simulating SCM could be analysed which clinically and morphologically were suspect of squamous cell or mucoepidermoid carcinoma. Five cases were localized in the parotid gland, 2 cases in the submandibular gland and 1 case in the palatinal glands. Tumour-simulating SCM was developed in pleomorphic adenomas (5 cases) and in multifocal adenomatous oncocytic hyperplasia (3 cases).

Adenoma, Pleomorphic↗
PubMed1997

Bilateral mucoepidermoid carcinomas arising in bilateral pre-existing Warthin's tumours of the parotid gland.

A unique case of bilateral mucoepidermoid carcinoma arising in pre-existing bilateral Warthin's tumours of the parotid glands is presented. Reports of carcinomas arising in pre-existing unilateral Warthin's tumours are likewise rare with only 3 cases of concern mucoepidermoid carcinoma. This is the first report of bilateral occurrence of mucoepidermoid carcinoma in Warthin's tumours in the literature. The pathogenesis and differential diagnosis are analysed.

Adenolymphoma↗
PubMed1997

[Salivary glands and the organism--interrelations and correlating reactions].

BACKGROUND: Functional disturbances and diseases of the salivary glands are not only conditioned by local factors, but are also based on the manifold connections of the salivary glands with the remaining organism. The salivary glands represent consequently a "mirror of diseases" and a "diagnostic fluid". METHODS: A comparing analysis of the data of the Salivary Gland Register Hamburg (more than 18,000 cases) with the details of the literature was performed. RESULTS: Interrelationships and correlations of the salivary glands exist especially in diseases of the immune system, in viral infections, in metabolic diseases and in diseases of the hormone or nerve system. The occurrence and concentration of a great number of substances identified in the saliva represent a monitoring system with conclusions to functional or morphological alterations of other organs. CONCLUSION: The salivary glands as an integral component of the oral cavity are connected consequently in a manifold manner with the remaining organism by interrelationships and correlations and represent thus a "mirror of diseases".

Diagnosis, Differential↗
PubMed1997

The spectrum of giant cells in tumours of the salivary glands: an analysis of 11 cases.

In view of the different terminology for salivary gland tumours with giant cells, eleven cases were analysed by histopathology and immunocytochemistry. Four cases (three pleomorphic adenomas, one carcinosarcoma in a pleomorphic adenoma) were classified as having a foreign-body giant cell reaction, and five cases (two mucoepidermoid carcinomas, one acinic cell carcinoma, two carcinomas in pleomorphic adenomas) as having a sarcomatoid osteoclast-like giant cell reaction. In two further cases a giant cell tumour and a giant cell granuloma were associated with carcinomas in pleomorphic adenomas. All giant cells showed characteristic expression of CD68 as a typical marker for histiocytes and macrophages with their origin in mononuclear haematopoetic stem cells. There was no evidence for an epithelial origin of the giant cells because all those examined had a negative reaction to cytokeratin. Foreign-body cells were characterized by cytoplasmic vacuoles and irregularly dispersed nuclei. They showed a focally circumscribed reaction mostly outside the connective tissue pseudocapsule of the tumours. The sarcomatoid osteoclast-like giant cell reactions in carcinomas were distinctly intermingled with the carcinomatous patterns. In contrast, the associated osteoclast-like giant cell tumour was distinctly separate from the salivary gland tumour tissue and was composed of numerous larger osteoclast-like giant cells with a greater number of nuclei (more than 20); these giant cells were uniformly distributed throughout the tumour tissue. The giant cell granuloma was also separate from the carcinoma and was composed of nests of smaller, more irregularly distributed giant cells.

Adenoma, Pleomorphic↗
PubMed1997

Analysis of AMPA receptor properties during postnatal development of mouse hippocampal astrocytes.

Glial cells in the mammalian brain express various types of voltage- and ligand-gated ion channels, including glutamate receptors (GluRs) of the alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)-subtype. In the present study we followed developmental changes in the functional properties of AMPA receptor (AMPA-R) channels expressed by astrocytes of the mouse hippocampus between postnatal days (P) 5-35 to learn more about the physiological significance of these glial receptors. A fast concentration clamp technique was applied to cells acutely isolated from the CA1 stratum radiatum subregion to quantitatively analyze rapidly activating and desensitizing receptor responses. The equilibrium responses of glutamate and kainate differed between P5 and P12. Although the maximum current induced by kainate was almost the same at all developmental stages, a steep rise in the maximum glutamate response was observed within the same time range. Between P5 and P12 there was an increase in the potentiation of AMPA-R currents with cyclothiazide (CTZ); at the same time, the dissociation kinetics of CTZ became significantly slower. These changes in the pharmacological properties suggested a variation in splice variant expression. With proceeding maturation, we observed an increase in the degree of desensitization of the glutamate- and AMPA-induced receptor currents. In addition to the shift in flip/flop splicing, these findings could hint at a developmental regulation of RNA editing in the arginine/glycine site. Altogether, the present results demonstrate changes in astrocytic AMPA-R functioning early in postnatal development, although after P12 the receptor properties remained almost constant. Although the overall Ca2+ permeability did not vary during development, the prolonged receptor opening in the early postnatal period causes an enhanced Na+/Ca2+ influx into the immature astrocytes. This could influence glial proliferation and differentiation during CNS ontogenesis.

Animals↗
PubMed1996

[Hyalinizing clear cell carcinoma of the salivary glands].

Many cell types of the salivary glands have clear cytoplasm. Causes of clear cytoplasmic quality in light microscopy are loss of organelles, storage of substances or fixation artefacts. Differential diagnosis of the different clear cell types requires special staining techniques, immunocytochemistry and electron microscopy. A new and distinct salivary gland neoplasm is hyalinizing clear cell carcinoma, which was not included in the second edition of the WHO Classification of Salivary Gland Tumors. Analysis of the collected cases of the Salivary Gland Register Hamburg and recent reports in the literature reveal that this carcinoma shows low-grade malignancy with localization usually in the minor salivary glands. Most cases occur in women. The pathohistology is characterized by solid or trabecular formations of polygonal clear cells which are surrounded by a broad hyalinized desmoplastic connective tissue stroma. The clear cells are mucin negative and express cytokeratin and EMA, in some cases also CEA, but not S-100 protein, actin or other markers of myoepithelial cells. Ultrastructural findings are undifferentiated duct cells with only few organelles and inclusion of glycogen granules. The differential diagnosis includes other clear cell tumours, especially epithelial-myoepithelial carcinoma and the clear cell variants of myoepithelial carcinoma and acinic cell or mucoepidermoid carcinoma.

Adenocarcinoma, Clear Cell↗
PubMed1996

Hybrid tumours of salivary glands. Definition and classification of five rare cases.

Hybrid tumours are very rare tumour entities which are composed of two different tumour entities, each of which conforms with an exactly defined tumour category. The tumour entities of a hybrid tumour are not separated but have an identical origin within the same topographical area. In contrast, biphasically differentiated tumours are a mixture of two cellular patterns with a corresponding term in the tumour classification. Examples of a biphasic differentiation are: basaloid-squamous carcinoma, adeno-squamous carcinoma or sarcomatoid carcinoma, and epithelial-myoepithelial carcinoma, mucoepidermoid carcinoma or adenoid cystic carcinoma. Hybrid tumours must also be distinguished from the multiple occurrence of salivary gland tumours which can develop syn- or metachronously. In the tissue samples of more than 6600 salivary gland tumours covered by the Salivary Gland Register (Institute of Pathology, University of Hamburg, Germany) only 5 cases of hybrid tumours were recorded between 1965 and 1994. This means less than 0.1% of all registered tumours. Case 1 was a very rare example of a hybrid adenoma with differentiation as a basal cell adenoma and a canalicular adenoma of the parotid gland. The similar cellular origin of both types of adenoma may be an explanation for its development in a hybrid adenoma. Case 2 is a hybrid tumour with a composition of basal cell adenoma and a glandular type of adenoid cystic carcinoma. In both types of tumours the two cell types (duct-lining cells and modified myoepithelial cells) have a similar histogenetic origin. Therefore, the development of the both cell types in a hybrid tumour with two trends of differentiation is possible. Case 3 represents a hybrid adenoma as a mixture of a Warthin tumour and a sebaceous adenoma. Although inclusions of sebaceous cells are observed in Warthin tumours, this hybrid tumour shows a composition of two different epithelial structures in a varied mixture. Case 4 is a very rare and unique hybrid carcinoma with two absolutely different components: acinic cell carcinoma and salivary duct carcinoma. The poor prognosis of this hybrid carcinoma is determined by the salivary duct carcinoma. Case 5 represents a hybrid carcinoma whose two components have a similar histogenetical basis: epithelial-myoepithelial carcinoma and a glandular type of adenoid cystic carcinoma. Both carcinomas are composed of variable proportions of ductlining cells and myoepithelial cells.

Aged↗
PubMed1996

Multiple tumours of the salivary glands--terminology and nomenclature.

Multiple tumours of the salivary glands are very rare and their combinations according to histological classification of the tumours, localisation and origin (origin in independent topographical areas or in the same tissue) are diverse. The following two categories can be distinguished: common occurrence of multiple salivary gland tumours with identical histology, or with different histology. In either group the tumours can be unilateral or bilateral, synchronous or metachronous. The most common multiple tumours with an identical histology are Warthin tumours and pleomorphic adenomas. Bilateral occurrence has been observed especially in oncocytomas, acinic cell carcinomas and basal cell adenomas. In the group of multiple tumours with differing histology, Warthin tumours and pleomorphic adenomas show a number of combinations with other adenomas or carcinomas of the salivary glands. Notable also is the simultaneous occurrence of salivary gland tumours with other oral tumours or extraglandular tumours, especially thyroid carcinomas and breast carcinomas. Multiple salivary gland tumours must be distinguished by nomenclature from tumours with biphasic differentiation and hybrid tumours. Tumours with biphasic differentiation are defined as regular, recurring mixtures of two cellular components in the same tumour and have a corresponding term in the tumour classification. Hybrid tumours are very rare and are composed of two different tumour entities within the same topographical area. Each of the tumour entities conforms with an exactly defined tumour category.

Adenolymphoma↗
PubMed1996

Mucoepidermoid carcinoma in a salivary duct cyst of the parotid gland. Contribution to the development of tumours in salivary gland cysts.

Concerning the hypothesis that distinct types of salivary gland cysts may be the starting point of a salivary gland tumour, a histological examination of 1,661 salivary gland cysts was performed in order to analyse the cell types and their proliferative activity. Epithelial alterations were found especially in salivary duct cysts of parotid gland and in mucous retention cysts of minor salivary glands. Characteristic cellular changes were epithelial metaplasias (goblet cells, clear cells, squamous cells) and focal epithelial proliferations with plump or papillary plaques projecting into the cyst lumen. Only in one case had a mucoepidermoid carcinoma developed in the wall of a parotid duct cyst. The epithelial metaplasia and focal proliferative activity in salivary duct cysts is comparable to similar alterations in odontogenic cysts as possible early manifestation of a tumour, especially of an ameloblastoma or mucoepidermoid carcinoma. The differential diagnosis of salivary duct cysts must take primarily cystadenomas and cystic mucoepidermoid carcinomas of well-differentiated type into account.

Carcinoma, Mucoepidermoid↗