Modulation of keratinocyte growth factor and its receptor in reepithelializing human skin.

We investigated the expression and distribution of keratinocyte growth factor (KGF) (FGF-7) and its receptor (KGFR) during reepithelialization of human skin. KGF mRNA levels increased rapidly by 8-10-fold and remained elevated for several days. In contrast, KGFR transcript levels decreased early but were significantly elevated by 8-9 d. A KGF-immunoglobulin G fusion protein (KGF-HFc), which specifically and sensitively detects the KGFR, localized the receptor to differentiating keratinocytes of control epidermis, but revealed a striking decrease in receptor protein expression during the intermediate period of reepithelization. Suramin, which blocked KGF binding and stripped already bound KGF from its receptor, failed to unmask KGFRs in tissue sections from the intermediate phase of wound repair. The absence of KGFR protein despite increased KGFR transcript levels implies functional receptor downregulation in the presence of increased KGF. This temporal modulation of KGF and KGFRs provides strong evidence for the functional involvement of KGF in human skin reepithelialization.

Specific receptor detection by a functional keratinocyte growth factor-immunoglobulin chimera.

Fibroblast growth factor receptors (FGFRs) are encoded by at least four distinct highly conserved genes, and alternative splicing generates multiple gene products. The close relationship among different FGFRs has greatly increased the difficulty in generating specific immunochemical probes. As an alternative strategy, we constructed a fusion protein comprising keratinocyte growth factor (KGF) and an IgG1 Fc domain (HFc). The chimeric molecule was efficiently secreted from transfectants as a disulfide-linked dimer that bound KGFRs with high affinity. Moreover, the KGF-HFc, like native KGF, induced DNA synthesis by epithelial cells implying normal functional receptor activation. Because it retained the convenient detection properties of an immunoglobulin, it was possible to use the KGF-HFc in ligand-mediated histochemical analysis of KGFRs. Flow cytometry revealed KGF-HFc chimera detection of the KGFR, an alternative FGFR2 product, but not FGFR1 (flg) or FGFR2 (bek). Histochemical analysis of normal skin demonstrated the specific localization of KGFRs within the spinous layer, a zone of epithelial cell differentiation. KGFRs were also localized to epithelial cells within a specific region of the hair follicle, and they were not detectable in cells of the sweat gland. Tissue sections of soft palate and tonsil, two examples of nonkeratinizing epithelium, revealed staining of stratum spinosum and some staining of the basal cell layer as well. Neither salivary gland epithelium nor lymphoid cells were positive. The ciliated epithelium of the trachea exhibited KGFR expression in intermediate and basal cell layers. In striking contrast to the normal pattern of staining in the adjacent epithelium, a squamous cell carcinoma of skin lacked detectable KGFRs. Our present findings suggest that growth factor-Ig fusion proteins may be generally applicable in ligand-mediated histochemical detection and localization of growth factor receptors.

Pseudoepithelial pattern in smears prepared from fine needle aspirates of plasmacytomas.

A pseudoepithelial pattern was observed in smears prepared from fine needle aspirates (FNA) from three plasmacytomas. In one case cells displayed a markedly granular, 'oncocytic' cytoplasm. Granularity of the cytoplasm was due to a large number of mitochondria as shown by electron microscopy. B-lymphocytic origin of the neoplasms was confirmed by immunocytochemistry.

[Possibilities of cytodiagnosis in ascites]. / Möglichkeiten der Zytodiagnostik im Aszites.

The examination of ascitic fluid is an important part in the diagnosis and control of gastrointestinal diseases. Different etiological conditions and pathological ways help develop different types of ascitic fluid. Variation of protein content (transudates/exsudates), variation of cells lead to different diagnosis. The following paper describes methods, diagnosis and differential diagnosis and limits of the cytological ascitic fluid examination.

Bioactivation of N-nitrosomethylbenzylamine and N-nitrosomethyl-amylamine in oesophageal papillomas.

Oesophageal papillomas were induced in male F344 rats by continuous exposure to N-nitrosomethylbenzylamine (NMBzA) and N-nitrosomethyl(2-methylbutyl)amine in the drinking water at concentrations of 10 and 19.5 p.p.m. respectively. After 81-141 days animals received a single i.p. chasing dose of NMBzA (0.1 mmol/kg), [14C-methyl]NMBzA or N-nitroso[14C-methyl]amylamine and were killed 6 h later. Induced papillomas (3-9 per animal) were analysed by autoradiography and by immunohistochemistry using a polyclonal antibody to O6-methyldeoxyguanosine. Both techniques revealed the presence of high levels of alkylation products in all papillomas investigated. Immunohistochemical staining of O6-methyldeoxyguanosine was largely restricted to nuclei of the basal layer and of epithelial cells with incipient keratinization. These findings demonstrate that NMBzA and N-nitrosomethylamylamine and probably related methylalkylnitrosamines are effectively bioactivated in premalignant lesions, indicating that during chronic exposure papillomas can acquire additional mutations that are likely to play a major role in tumour progression.

[Pattern of intermediate filaments in thymomas]. / Intermediärfilamentmuster von Thymomen.

The cytokeratin pattern of medullary, mixed and cortical thymomas and thymic carcinomas were analyzed by two-dimensional equilibrium electrophoresis. Extracts from a medullary thymoma and normal, total thymi showed a similar pattern. On the other hand in cortical thymomas and very similar in thymic carcinomas there were marked changes in the cytokeratin pattern. These findings support the classification of thymomas as described by MULLER-HERMELINK.

[Immunophenotypic and genotypic characterization of T-cell populations in thymomas]. / Immunphaenotypische und genotypische Charakterisierung der T-Zellpopulation in Thymomen.

The T cell component of eight thymomas has been studied by immunohistochemistry and Southern blot analysis. In the cortical areas of thymomas the T cells expressed an immature cortical phenotype. In cortical and medullary areas T cell Receptor (TcR) alpha-beta lymphocytes heavily predominated over TcR gamma-delta lymphocytes. No genomic rearrangement of TcR and Immunoglobulin genes could be detected, thus supporting the non neoplastic nature of the lymphocyte component in thymomas.

Leaking giant aneurysm of the aortic root due to cystic medial necrosis with pericardial tamponade mimicking type-A aortic dissection.

The diagnosis of acute type-A aortic dissection is predominantly based on the demonstration of an intimal tear or a dissection membrane. We describe another pathogenetic mechanism in a patient with the typical features of acute aortic dissection with pericardial tamponade, and a giant aneurysm of the ascending aorta. However, no dissection membrane, rupture site, or intimal tear could be demonstrated by transesophageal echocardiography, intraoperatively, or histologically. The histological work-up showed an extreme form of cystic medial necrosis with intramural hemorrhages consistent with a leaking aneurysm. Hence, in a patient with a symptomatic aneurysm of the aortic root and pericardial tamponade, obvious intimal dissection or rupture does not always have to be present echocardiographically or intraoperatively. A different presentation can occur in the setting of an extreme medial necrosis, where blood leaks through the aortic wall causing intramural hemorrhages with intimal leaks invisible to the surgeon's or echocardiographer's eye. This process is clinically indistinguishable from type-A aortic dissection.