[Molecular pathology of tuberculosis : Status, methodology, and limits]. / Molekularpathologie der Tuberkulose : Stellenwert, Methodik und Grenzen.

In the diagnosis of mycobacterioses, microbiological examination with culture and antibiogram, possibly in combination with molecular biological testing of the fresh material, still represents the gold standard. However, these methods are not available for formalin-fixed paraffin-embedded (FFPE) material or other fixed samples. For this reason, the first step in pathology is to attempt microscopic pathogen detection (ZN/Fite/rhodamine-auramine). Subsequently, molecular pathological examination for the detection of mycobacterial gene sequences should also be considered mandatory today. Although this has clear limits due to the material, it is nevertheless well suited, if carried out correctly, to detect a mycobacterial infection or make it unlikely. A negative result may favor an alternative diagnosis but does not completely rule out mycobacteriosis.For the therapy of tuberculosis or nontuberculous mycobacterial (NTM) disease, the reliable detection of the species and the determination of resistance is of utmost importance. With regard to therapy, the clinician cannot afford to make a false diagnosis. In case of doubt, a rebiopsy for sampling native material, particularly for microbiological testing, should be discussed.

Meat allergy associated with galactosyl-α-(1,3)-galactose (α-Gal)-Closing diagnostic gaps by anti-α-Gal IgE immune profiling.

BACKGROUND: Glycoproteins and glycolipids of some mammalian species contain the disaccharide galactosyl-α-(1,3)-galactose (α-Gal). It is known that α-Gal is immunogenic in humans and causes glycan-specific IgG and also IgE responses with clinical relevance. α-Gal is part of the IgE-reactive monoclonal therapeutic antibody cetuximab (CTX) and is associated with delayed anaphylaxis to red meat. In this study, different α-Gal-containing analytes are examined in singleplex and multiplex assays to resolve individual sensitization patterns with IgE against α-Gal. METHODS: Three serum groups, α-Gal-associated meat allergy (MA) patients, idiopathic anaphylaxis (IA) patients with suspected MA, and non-meat-allergic healthy control individuals (HC), were analyzed via singleplex allergy diagnostics and a newly established immunoblot diagnostic system. The new dot blot detection system resolved individual IgE sensitization profiles for α-Gal-containing analytes CTX, bovine thyroglobulin (Bos d TG), and human serum albumin (HSA)-conjugated α-Gal. RESULTS: Singleplex allergy diagnostics using the α-Gal analytes CTX and Bos d TG confirms the history of MA patients in 91% and 88% of the cases, respectively. A novel dot blot-based assay system for the detection of IgE against α-Gal reveals individual IgE sensitization profiles for α-Gal-containing analytes. An α-Gal-associated IgE cross-reactivity profile (IgE against CTX, Bos d TG, and HSA-α-Gal) was identified, which is associated with MA. CONCLUSIONS: Detection of individual sensitization patterns with different α-Gal-containing analytes provides the basis for an individual allergy diagnosis for α-Gal-sensitized patients. Higher amounts of α-Gal in pork and beef innards compared to muscle meat as indicated by a higher staining intensity are a plausible explanation for the difference in allergic symptom severity.

[A reduced TKI dosage is not associated with loss of activity in EGFR mutated NSCLC patients]. / Reduzierte Dosis von TKI führt nicht zu Wirkungsverlust bei Patienten mit aktivierender EGFR-Mutation.

BACKGROUND: Patients treated with anti-EGFR tyrosine kinase inhibitors (TKI) may receive dose reduction due to toxicity; however, the impact on treatment efficacy and patient outcome remains unknown. PATIENTS AND METHODS: Patients with stage IV NSCLC harbouring EGFR mutations and treated at our institution were retrospectively analyzed for treatment with TKI in 2012 or later. RESULTS: Thirty patients with EGFR mutated adenocarcinoma were identified meeting the inclusion criteria. Eleven patients received cytotoxic therapy as first line treatment yielding in a response rate of 36 %. All patients were treated with TKI as first or second-line therapy which resulted in disease stabilization (23 %) or response (77 %) in all patients. The median progression-free survival was 21.4 months with 21 patients still on treatment with TKI. For 7 patients, the dose of TKI treatment had to be reduced due to co-morbidities (n = 2) or skin toxicity (rash ≥ grade 3; n = 5). These patients demonstrated a similar response and outcome as compared to patients receiving full dose TKI treatment. CONCLUSION: Patients with EGFR mutated NSCLC and the need for TKI dose reduction seem to benefit in a similar manner from TKI therapy.

Glioma infiltration of the corpus callosum: early signs detected by DTI.

The most frequent primary brain tumors, anaplastic astrocytomas (AA) and glioblastomas (GBM): tend to invasion of the surrounding brain. Histopathological studies found malignant cells in macroscopically unsuspicious brain parenchyma remote from the primary tumor, even affecting the contralateral hemisphere. In early stages, diffuse interneural infiltration with changes of the apparent diffusion coefficient (ADC) and fractional anisotropy (FA) is suspected. The purpose of this study was to investigate the value of DTI as a possible instrument of depicting evidence of tumor invasion into the corpus callosum (CC). Preoperatively, 31 patients with high-grade brain tumors (8 AA and 23 GBM) were examined by MRI at 3 T, applying a high-resolution diffusion tensor imaging (DTI) sequence. ADC- and FA-values were analyzed in the tumor-associated area of the CC as identified by fiber tracking, and were compared to matched healthy controls. In (MR-)morphologically normal appearing CC the ADC values were elevated in the tumor patients (n = 22; 0.978 × 10(-3) mm²/s) compared to matched controls (0.917 × 10(-3) mm²/s, p < 0.05), and the corresponding relative FA was reduced (rFA: 88 %, p < 0.01). The effect was pronounced in case of affection of the CC visible on MRI (n = 9; 0.978 × 10(-3) mm²/s, p < 0.05; rFA: 72 %, p < 0.01). Changes in diffusivity and anisotropy in the CC can be interpreted as an indicator of tumor spread into the contralateral hemisphere not visible on conventional MRI.

Effects of antimicrobial peptides on methanogenic archaea.

As members of the indigenous human microbiota found on several mucosal tissues, Methanobrevibacter smithii and Methanosphaera stadtmanae are exposed to the effects of antimicrobial peptides (AMPs) secreted by these epithelia. Although antimicrobial and molecular effects of AMPs on bacteria are well described, data for archaea are not available yet. Besides, it is not clear whether AMPs affect them as the archaeal cell envelope differs profoundly in terms of chemical composition and structure from that of bacteria. The effects of different synthetic AMPs on growth of M. smithii, M. stadtmanae, and Methanosarcina mazei were tested using a microtiter plate assay adapted to their anaerobic growth requirements. All three tested methanoarchaea were highly sensitive against derivatives of human cathelicidin, of porcine lysin, and a synthetic antilipopolysaccharide peptide (Lpep); however, sensitivities differed markedly among the methanoarchaeal strains. The potent AMP concentrations affecting growth were below 10 µM, whereas growth of Escherichia coli WBB01 was not affected at peptide concentrations up to 10 µM under the same anaerobic growth conditions. Atomic force microscopy and transmission electron microscopy revealed that the structural integrity of the methanoarchaeal cells is destroyed within 4 h after incubation with AMPs. The disruption of the cell envelope of M. smithii, M. stadtmanae, and M. mazei within a few minutes of exposure was verified by using LIVE/DEAD staining. Our results strongly suggest that the release of AMPs by eukaryotic epithelial cells is a potent defense mechanism targeting not only bacteria, but also methanoarchaea.

Pulmonary haptoglobin and CD163 are functional immunoregulatory elements in the human lung.

BACKGROUND: The acute-phase protein haptoglobin (Hp) and its receptor CD163 serve as immunomodulators and possess anti-inflammatory besides antioxidant functions. OBJECTIVES: To further understand the role of the recently described pulmonary Hp (pHp) and its receptor CD163 in case of inflammation and infection, pHp and CD163 were investigated on mRNA and protein level to gain insight into the cellular events taking place upon stimulation with the inflammatory mediators LPS, Pam3, cytokine IL-6 and dexamethasone, and upon infection with respiratory pathogens (Haemophilus influenzae, Streptococcuspneumoniae and Chlamydia pneumoniae) by use of a human ex vivo tissue culture model and cell cultures of A549 and alveolar epithelial cells type II. In addition, pHp and CD163 expression in COPD and sarcoidosis was assessed. METHODS: We conducted experiments using 942 ex vivo cultured lung samples applying immunohistochemistry, immunocytochemistry, in situ hybridization, immunofluorescence, real-time PCR, RT-PCR, slot and Western immunoblot analyses with tissue lysates and culture supernatants as well as ELISA and cytometric bead array analyses. RESULTS: This study describes for the first time the expression, regulation and secretion of pHp and its receptor CD163 in the human lung. The release of soluble mediators from A549 cell line and human monocyte-derived macrophages was observed indicating that Hp differentially activates the release of soluble mediators and major chemoattractants. CONCLUSIONS: The findings indicate a native function of pHp and CD163 as functional pulmonary defense elements due to local expression, regulation and secretion during lung infection and as part of the inflammatory immune response of the respiratory system.

Generation and evaluation of a monoclonal antibody, designated MAdL, as a new specific marker for adenocarcinomas of the lung.

BACKGROUND: Different therapy regimens in non-small-cell lung cancer (NSCLC) are of rising clinical importance, and therefore a clear-cut subdifferentiation is mandatory. The common immunohistochemical markers available today are well applicable for subdifferentiation, but a fraction of indistinct cases still remains, demanding upgrades of the panel by new markers. METHODS: We report here the generation and evaluation of a new monoclonal antibody carrying the MAdL designation, which was raised against primary isolated human alveolar epithelial cells type 2. RESULTS: Upon screening, one clone (MAdL) was identified as a marker for alveolar epithelial cell type II, alveolar macrophages and adenocarcinomas of the lung. In a large-scale study, this antibody, with an optimised staining procedure for formalin-fixed tissues, was then evaluated together with the established markers thyroid transcription factor-1, surfactant protein-A, pro-surfactant protein-B and napsin A in a series of 362 lung cancer specimens. The MAdL displays a high specificity (>99%) for adenocarcinomas of the lung, together with a sensitivity of 76.5%, and is capable of delivering independent additional diagnostic information to the established markers. CONCLUSION: We conclude that MAdL is a new specific marker for adenocarcinomas of the lung, which helps to clarify subdifferentiation in a considerable portion of NSCLCs.

Tumors in the lung--morphologic features and the challenge of integrating biomarker signatures into diagnostics.

In the last decade, pathologic approaches concerning diagnosis and treatment of lung carcinomas have increasingly moved towards the implementation of molecular methods into the process of decision. In this study, an overview is given referring to the variety of tumors in the lung including common primary lung neoplasms and secondary tumors, and a modus operandi is presented which integrates immunology as well as molecular pathology within the process of finding correct diagnoses. Besides the conventional and approved methods and techniques leading to appropriate treatment including so-called targeted therapies, pathologist's work meanwhile depends on both histologic and molecular results. Since molecular techniques have increasingly entered the field of routine diagnostics, challenges and possibilities have changed and are still rapidly developing. The proceeding integration of molecular-biologic investigations into the process of diagnosing has changed the nature of diagnostics and will continuously grow in the near future. Only by obtaining a proper diagnosis, the optimal treatment of a patient can be assured, whereupon the knowledge of gene mutations and/or altered protein expression is crucial. By identifying those novel molecular target structures, the therapeutic spectrum is tremendously enlarged and will finally improve the patient's prognosis by personalized targeted therapies.

Expression analysis of EML4 in normal lung tissue and non-small cell lung cancer (NSCLC) in the absence and presence of chemotherapeutics.

Despite considerable progress in the development of individualized targeted therapies of tumor diseases, identification of additional reliable target molecules is still mandatory. One of the most recent targets is microtubule-associated human EML4 generating a fusion-type oncogene with ALK demonstrating marked transforming activity in lung cancer. Since EML4 is a poorly characterized protein with regard to expression, function and regulation in human tissue, specimens of human tumor and tumor-free tissues obtained from patients with NSCLC were analyzed to determine the cellular localization. All tissue samples have been previously fixed with the novel HOPE-technique and paraffin embedded. Determination of both gene expression and protein levels of EML4 were performed using RT-PCR, in situ hybridization as well as immunohistochemistry, respectively. In human NSCLC tissue samples, possible regulation of EML4 transcription upon chemotherapy with combinations of most established cytotoxic drugs for NSCLC treatment was also studied employing the recently established ex vivo tissue culture model STST. In normal lung, both marked mRNA and protein levels of EML4 were localized in alveolar macrophages. In contrast, lung tumor tissues always showed consistent transcriptional expression in situ and by RT-PCR. Stimulation of NSCLC tissues with chemotherapeutics revealed heterogeneous effects on EML4 mRNA levels. Based on its expression patterns in both tumor-free lung and NSCLC tissues, human EML4 is likely to be closely associated with processes involved in local inflammation of the lung as well as with tumor behavior. Thus, our results suggest that EML4 may have the potential as a therapeutic target molecule in NSCLC chemotherapy.

Malignant and non-malignant lung tissue areas are differentially populated by natural killer cells and regulatory T cells in non-small cell lung cancer.

Even though the lung represents a special immune compartment with the capacity of a high inflammatory response, ineffective anti-tumour immunity is common in lung-associated malignancies. We asked whether a differential composition of the immune cell infiltrate in malignant (MLTAs) and non-malignant lung tissue areas (N-MLTAs) exists and might potentially contribute to this effect. We performed a comparative analysis of immune cells residing in MLTAs and N-MLTAs of non-small cell lung cancer (NSCLC) patients. To this end, we used immunophenotyping and functional analyses on directly isolated immune cells and tissue arrays on archived paraffin-embedded specimens. A strong T cell infiltration was prominent in both tissue compartments whereas CD4(+)CD25(+)CD127(-) T regulatory cells were present in MLTAs only. Nonetheless, concurrent functional ex vivo T cell analyses revealed no significant difference between T cells of MLTA and N-MLTA, suggesting that tumour-infiltrating T cells were not functionally impaired. Interestingly, T cell infiltration was less pronounced in specimens with a high neutrophilic infiltrate. NK cell infiltration was strikingly heterogenous between MLTA and N-MLTA. While NK cells were almost absent in the malignant tissue regions, non-malignant counterparts were selectively populated by NK cells and those NK cells showed strong cytotoxic activity ex vivo. We report that malignant and non-malignant tissue areas in NSCLC are selectively infiltrated by certain immune cell types with NK cells being displaced from the tumour tissue. These phenomena have important implications for tumour immunology of NSCLC and should be considered for the development of future immunologic intervention therapies.

The HOPE technique opens up a multitude of new possibilities in pathology.

Fixation of tissues with formalin results in well-preserved morphology but to a high degree leads to degradation of nucleic acids, which substantially constricts the spectrum of applicable molecular techniques. The novel HOPE-fixative with subsequent paraffin embedding, as an alternative to formalin, has been shown to result in a morphological preservation comparable to formalin-fixed, paraffin-embedded specimens. Due to a similar workflow like in formalin-fixation and paraffin embedding, the HOPE technique can be successfully established within any pathological institute. We have shown that DNA, RNA and proteins are protected in HOPE-fixed, paraffin-embedded tissues for at least eight years. Moreover, we described procedures which permit successful application of all common molecular techniques such as in situ hybridization targeting either DNA or RNA, immunohistochemistry without antigen retrieval and for formalin-refractory antigens, PCR, RT-PCR, Western blot, Northern blot, and transcription microarrays to HOPE-fixed, paraffin-embedded tissues. Furthermore, HOPE-fixed tissues can be used for the construction of tissue microarrays for enhanced high-throughput analyses on the molecular level. Using the HOPE technique as its crucial methodological base, ex vivo model systems could be established, e.g. for the simulation of early events in human infections and detection of chemotherapy resistances in human cancer. In addition to tissues, cell-culture preparations have been prepared utilizing the HOPE technique, which were then successfully applied to in situ hybridization targeting mRNA or immunocytochemistry with excellent preservation of morphological details. Taken together, the HOPE technique to date represents an alternative fixation that is, in contrary to other procedures, scientifically broadly analyzed. Therefore new possibilities are opened up especially within the rapidly growing field of molecular pathology.

Improved detection of mycobacterial DNA by PCR in formalin-fixed, paraffin-embedded tissues using thin sections.

PCR is a unique methodology allowing for the sensitive detection of mycobacterial DNA-sequences in cases in which no fresh material can be obtained for classic analyses. Despite the limitations of this technique, for example the less satisfactory quality of DNA from paraffin-embedded specimens and the high effort necessary to control contamination, PCR still represents a useful additional tool for routine diagnostic examinations of mycobacterial infections. Fragmentation of the DNA extracted from formalin-fixed, paraffin-embedded samples on the one hand and the rigid cell wall of mycobacteria on the other hand are obstacles to detecting the DNA of these microorganisms by PCR. Here, we describe a simple mechanical procedure that allows us to improve the detection of mycobacterial DNA with the use of thin (1 microm) sections instead of thicker sections. This could be explained by a gentle, mechanical opening of the acid fast mycobacterial cell wall. Thus, even the application of heat/cold shock treatments is not necessary. This inexpensive fast procedure can also be used for the detection of other infectious agents.

Mechanisms of acrylamide formation: Maillard-induced transformation of asparagine.

The formation of acrylamide (AA) from L-asparagine was studied in Maillard model systems under pyrolysis conditions. While the early Maillard intermediate N-glucosylasparagine generated approximately 2.4 mmol/mol AA, the Amadori compound was a less efficient precursor (0.1 mmol/mol). Reaction with alpha-dicarbonyls resulted in relatively low AA amounts (0.2-0.5 mmol/mol), suggesting that the Strecker aldehyde pathway is of limited relevance. Similarly, the Strecker alcohol 3-hydroxypropanamide generated low amounts of AA (0.2 mmol/mol). On the other hand, hydroxyacetone afforded more than 4 mmol/mol AA, indicating that alpha-hydroxycarbonyls are more efficient than alpha-dicarbonyls in transforming asparagine into AA. The experimental results are consistent with the reaction mechanism proposed, i.e. (i) Strecker-type degradation of the Schiff base leading to azomethine ylides, followed by (ii) beta-elimination of the decarboxylated Amadori compound to release AA. The functional group in beta-position on both sides of the nitrogen atom is crucial. Rearrangement of the azomethine ylide to the decarboxylated Amadori compound is the key step, which is favored if the carbonyl moiety contains a hydroxyl group in beta-position to the N-atom. The beta-elimination step in the amino acid moiety was demonstrated by reacting under pyrolysis conditions decarboxylated model Amadori compounds obtained by synthesis.

Phenotype and genotype associations of lung carcinoma with atypical adenomatoid hyperplasia, squamous cell dysplasia, and chromosome alterations in non-neoplastic bronchial mucosa.

The frequency of preneoplastic lesions of the lung and bronchial mucosa as well as potential genotype alterations in spatial relationship to pulmonary malignancies still need intensive investigations in order to understand the occurrence and manifestation of lung cancer in detail. To investigate the contemporary manifestation of lung cancer precursor lesions, peripheral (non-neoplastic) lung parenchyma and bronchial mucosa of operated lung carcinomas were analyzed at distinct distances (1, 2, 3, and 4 cm) from the tumor boundary for pre-neoplastic lesions--atypical adenomatoid hyperplasia (AAH) and squamous cell dysplasia (SCD), in 150 surgical specimens. Short-term tissue cultures of additional 55 primary and secondary lung tumors and their surrounding non-neoplastic bronchial mucosa were performed at the same distances in order to search for chromosome alterations, i.e. genotype aberrations. In phenotype observations, atypical adenomatoid hyperplasia was noted in 19/150 (13%) cases, and squamous cell dysplasia in 46/150 (31%) cases. The degree of cellular atypia decreased with increasing distance from the tumor boundary in both AAH and SCM. AAH was observed more frequently in adenocarcinomas, SCQ more frequently in squamous cell carcinomas. In genotype observations, the average number of abnormal metaphases measured 4.5/10 high power fields (HPF) in primary lung carcinomas, and only 2/10 in metastases. Data indicate that the so-called preneoplastic lesions in the lung are not completely tumor-precursor lesions, but, in addition, induced by the tumor itself.

Improved diagnostics targeting c-MET in non-small cell lung cancer: expression, amplification and activation?

BACKGROUND: Several c-MET targeting inhibitory molecules have already shown promising results in the treatment of patients with Non-small Cell Lung Cancer (NSCLC). Combination of EGFR- and c-MET-specific molecules may overcome EGFR tyrosine kinase inhibitor (TKI) resistance. The aim of this study was to allow for the identification of patients who might benefit from TKI treatments targeting MET and to narrow in on the diagnostic assessment of MET. METHODS: 222 tumor tissues of patients with NSCLC were analyzed concerning c-MET expression and activation in terms of phosphorylation (Y1234/1235 and Y1349) using a microarray format employing immunohistochemistry (IHC). Furthermore, protein expression and MET activation was correlated with the amplification status by Fluorescence in Situ Hybridization (FISH). RESULTS: Correlation was observed between phosphorylation of c-MET at Y1234/1235 and Y1349 (spearman correlation coefficient rs = 0.41; p < 0.0001). No significant correlation was shown between MET expression and phosphorylation (p > 0.05). c-MET gene amplification was detected in eight of 214 patients (3.7%). No significant association was observed between c-MET amplification, c-MET protein expression and phosphorylation. CONCLUSION: Our data indicate, that neither expression of c-MET nor the gene amplification status might be the best way to select patients for MET targeting therapies, since no correlation with the activation status of MET was observed. We propose to take into account analyzing the phosphorylation status of MET by IHC to select patients for MET targeting therapies. Signaling of the receptor and the activation of downstream molecules might be more crucial for the benefit of therapeutics targeting MET receptor tyrosine kinases than expression levels alone.

Localization of ceramide and glucosylceramide in human epidermis by immunogold electron microscopy.

Ceramides and glucosylceramides are pivotal molecules in multiple biologic processes such as apoptosis, signal transduction, and mitogenesis. In addition, ceramides are major structural components of the epidermal permeability barrier. The barrier ceramides derive mainly from the enzymatic hydrolysis of glucosylceramides. Recently, anti-ceramide and anti-glucosylceramide anti-sera have become available that react specifically with several epidermal ceramides and glucosylceramides, respectively. Here we demonstrate the detection of two epidermal covalently bound omega-hydroxy ceramides and one covalently bound omega-hydroxy glucosylceramide species by thin-layer chromatography immunostaining. Moreover, we show the ultrastructural distribution of ceramides and glucosylceramides in human epidermis by immunoelectron microscopy on cryoprocessed skin samples. In basal epidermal cells and dermal fibroblasts ceramide was found: (i) at the nuclear envelope; (ii) at the inner and outer mitochondrial membrane; (iii) at the Golgi apparatus and the endoplasmic reticulum; and (iv) at the plasma membrane. The labeling density was highest in mitochondria and at the inner nuclear membrane, suggesting an important role for ceramides at these sites. In the upper epidermis, ceramides were localized: (i) in lamellar bodies; (ii) in trans-Golgi network-like structures; (iii) at the cornified envelope; and (viii) within the intercellular space of the stratum corneum, which is in line with the known analytical data. Glucosylceramides were detected within lamellar bodies and in trans-Golgi network-like structures of the stratum granulosum. The localization of glucosylceramides at the cornified envelope of the first corneocyte layer provides further proof for the existence of covalently bound glucosylceramides in normal human epidermis.

EnVision+, a new dextran polymer-based signal enhancement technique for in situ hybridization (ISH).

Seventy paraffin-embedded cervical biopsy specimens and condylomata were tested for the presence of human papillomavirus (HPV) by conventional in situ hybridization (ISH) and ISH with subsequent signal amplification. Signal amplification was performed either by a commercial biotinyl-tyramide-based detection system [GenPoint (GP)] or by the novel two-layer dextran polymer visualization system EnVision+ (EV), in which both EV-horseradish peroxidase (EV-HRP) and EV-alkaline phosphatase (EV-AP) were applied. We could demonstrate for the first time, that EV in combination with preceding ISH results in a considerable increase in signal intensity and sensitivity without loss of specificity compared to conventional ISH. Compared to GP, EV revealed a somewhat lower sensitivity, as measured by determination of the integrated optical density (IOD) of the positively stained cells. However, EV is easier to perform, requires a shorter assay time, and does not raise the background problems that may be encountered with biotinyl-tyramide-based amplification systems. (J Histochem Cytochem 49:1067-1071, 2001)

The prognostic value of the expression of collagenase IV, cathepsin D and metallothionein in squamous cell carcinomas of the skin determined by immunohistochemistry.

We analyzed 53 specimens from primary squamous cell carcinomas of the skin for the expression of collagenase IV, cathepsin D and metallothionein by means of immunohistochemistry along with histological data. We compared tumors that metastasized (30) with tumors that did not (23) during a follow-up period of at least 5 years. The expression of the two proteolytic enzymes cathepsin D and collagenase IV was also assessed at the invading front of the tumors. Statistical analyses revealed significant differences for the overall expression of cathepsin D (P < 0.05), expression of cathepsin at the invading front (P < 0.05) and the tumor thickness (P < 0.01). The results showed that cathepsin D may be a prognostic factor for squamous cell carcinomas of the skin. We then combined the results of parameters with statistically significant differences by multiplication. The prognostic value of such a combined risk-factor score showed higher confidence than any of the single parameters alone: a sensitivity of 63.3%, a specificity of 87.0% and an efficiency of 73.6%. This kind of combined risk-factor score might be used to more accurately detect patients at high risk of metastasis.

DNA-printing: utilization of a standard inkjet printer for the transfer of nucleic acids to solid supports.

The use of total cDNA as a probe for hybridization enables the transcription level of a large number of genes to be analyzed at the same time. Some effort has been spent to develop high density gene arrays on different solid supports to facilitate this hybridization. We achieved a high resolution by utilizing inkjet printer technology as a useful alternative to blotting the target genes onto a membrane. By the use of an ordinary inkjet printer model we show that it is possible to print DNA onto hybridization membranes and hybridize using either specific genes or total cDNA as probes. The high resolution of these prints (300 dpi) might be used in the future to construct complex micro-arrays to analyze simultaneously large numbers of genes.