Model and simulation of multivalent binding to fixed ligands

A model to quantitate the principal aspects of multivalent binding was developed. It describes the random distribution of an immobilized component (the ligand) taking into account local densities. The binding of a bivalent molecule (the analyte) to the ligand is described as occurring in two steps, the second of which is driven by the local concentration of neighboring ligands. The model was used to simulate the kinetics of bivalent binding in surface plasmon resonance biosensors such as BIAcore. The simulations are compared with measured data. The simulation quantitates the influence of bivalent binding on the sensor signal, as a function of ligand density, analyte concentration, and binding site distance. Such simulations will be helpful for understanding and designing experiments to assess avidity effects as well as for developing molecules with high avidity. Furthermore, they help to analyze the inherent complexity in seemingly simple sensorgrams.

A dimeric bispecific miniantibody combines two specificities with avidity

Bispecific antibodies extend the capabilities of nature and might be applied in immunotherapy and biotechnology. By fusing the gene of a single-chain Fv (scFv) fragment to a helical dimerization domain, followed by a second scFv fragment of different specificity, we were able to express a functional protein in E. coli, which is bispecific and has two valencies for each specificity. The dimeric bispecific (DiBi) miniantibody preserves the natural avidity of antibodies in a very small-sized molecule of only 120 kDa. The generality of the principle was shown with a scFv fragment binding the EGF-receptor (named scFv 425) in three combinations with scFv fragments either directed against CD2 (ACID2.M1), phosphorylcholine (McPC603) or fluorescein (FITC-E2). Binding was analyzed by sandwich surface plasmon resonance biosensor (BIAcore) measurements.

[Myositis proliferans: a pseudosarcomatous lesion in soft tissue]

Myositis proliferans is a reactive, intramuscular soft tissue disease characterized by fibroblast and myofibroblast proliferation, showing similarities to the phase-like development seen in the general pathology of wound healing and hypertrophic scars. Immunohistochemically, a combined expression of vimentin and alpha-sm actin is seen in the spindle-shaped cell formations. The decisive histological preparations is supported by immunohistochemical techniques, especially in the differentiation from sarcoma. If a definite diagnosis is made, incomplete excision may suffice.

Expression of type IV collagenase correlates with the expression of vascular endothelial growth factor in primary non-small cell lung cancer

Tumor growth and metastasis are angiogenesis-dependent processes initiated and regulated by a number of cytokines. Vascular endothelial growth factor (VEGF) is a potent angiogenic protein with a selective mitogenic effect on vascular endothelial cells, known to be involved in physiological (embryogenesis) and pathophysiological (rheumatoid arthritis, tumor) angiogenesis. An increased expression of matrix metalloproteinase type IV collagenase has been reported in invading endothelial cells in vitro and in malignant cells, degrading structures of the basement membranes in various human malignancies. In the present study we investigated the expression of the genes for type IV collagenase and vascular endothelial growth factor (VEGF) in 40 cases of primary non-small-cell lung cancer (NSCLC). Specimens were immunostained by an antibody directed against VEGF and mRNA transcripts of VEGF and type IV collagenase were localized by non-radioactive in situ hybridization. VEGF mRNA was detected in 33 neoplasms, while in 23 cases transcripts of the type IV collagenase gene were visualized by digoxigenin-labeled cDNA probes. Transcripts of both mRNAs were detected in malignant cells. Furthermore, anti-VEGF immunostaining was present in newly formed microvessels close to the atypical cells, and mRNA of type IV collagenase was present in stromal cells adjacent to the tumor. A statistically significant correlation was found between the expression of type IV collagenase and VEGF (P = 0.0061). These data suggest a double role for type IV collagenase in the metastatic process of NSCLC: (1) facilitating the invasion of tumor cells by the proteolytic cleavage of the basement membrane and (2) similarly supporting the endothelial cell invasion essential for tumor angiogenesis. Furthermore, our findings sustain the hypothesis that metastatic spread and angiogenesis are associated with a clonal expansion of highly angiogenic and invasive tumor cell clones.

Static DNA cytometry as a diagnostic aid in effusion cytology: I. DNA aneuploidy for identification and differentiation of primary and secondary tumors of the serous membranes

OBJECTIVE

To determine whether DNA aneuploidy is a sensitive and specific marker for the identification of tumor cells in effusions and whether the pattern of DNA aneuploidy can provide important information for the differential diagnosis of primary and secondary tumors of the serous membranes.

STUDY DESIGN

One hundred eight malignant mesotheliomas as well as 102 metastatic carcinomas of the serous membranes were obtained from routine cytologic and histologic material. One hundred reactive effusions were investigated as controls. Nuclear DNA contents were measured after Feulgen staining using a TV image analysis system.

RESULTS

DNA aneuploidy was assumed if abnormal DNA stemlines, a coefficient of variation of the first DNA stemline > or = 10%, or cells > 9c were observed. On this basis the prevalence of DNA aneuploidy in mesotheliomas was 83% for cytologic and 84% for histologic material. In effusions of metastatic carcinomas it was 100%. None of the 100 reactive effusions revealed DNA aneuploidy (prevalence, 0%). Positive predictive value for mesotheliomas was 100%; negative predictive value was 88% for cytologic and 82% for histologic material. Positive predictive value for metastatic carcinomas was 100%; negative predictive value was 100%. Seventy-two percent of the mesotheliomas revealed their greatest stemline within the range 1.80c-2.20c, whereas none of the metastatic carcinomas showed this stemline position.

CONCLUSION

DNA image cytometry might be a very sensitive and highly specific, additional tool for identification of neoplastic cells in effusions as well as for the differential diagnosis of mesothelioma vs. metastatic carcinoma of the serous membranes.

Tandem immobilized metal-ion affinity chromatography/immunoaffinity purification of His-tagged proteins--evaluation of two anti-His-tag monoclonal antibodies

A tag comprising four to six histidines genetically fused to the protein of interest (His-tag) has been widely used to purify proteins by immobilized metal-ion affinity chromatography (IMAC). Here we report the utilization of the same tag twice in series, first for IMAC and subsequently for immunoaffinity purification. Both steps are based on completely different physical principles and can therefore remove different contaminants. Two anti-His-tag antibodies (3D5 and PentaHis) were characterized for their binding and elution properties using the BIAcore surface plasmon resonance biosensor. The dissociation constant of the PentaHis antibody was determined to be 1 x 10(-8) M and for the 3D5 antibody 3.4 x 10(-7) M at pH 7.4. Imidazole in the sample did interfere with binding, whereas chelating agents such as EDTA and high salt did not. The antibody 3D5 was coupled to a column matrix and used for a coupled two-step purification, in which the IMAC column is eluted with EDTA and the eluent is loaded directly on the immunoaffinity column. This method may constitute a very general procedure to purify proteins to near homogeneity without the need to tailor conditions individually, and it may thus be very attractive for high-throughput screening programs and for developing general protocols for clinical grade material.

[Pleural reaction pattern after talc pleurodesis]

Because of the rising importance of talcum pleurodesis in the therapeutic management of malignant and benign pleural effusions in Germany, pleural samples after talcum pleurodesis were compared to microscopic, immunohistochemical, and scanning electron microscopy findings after Tetracyclin and Novantron pleurodesis in 24 patients up to 18 months after intrapleural therapy. The histomorphological findings after talcum pleurodesis show an early phase of up to 4 weeks, characterized by the presence of talcum-containing granulation tissue with giant-cell foreign-body reaction, and a subsequent late phase with organization of the granulation tissue and connective tissue formation and obliteration of the pleura sheets. The resulting characteristic linear talcum zone in the pleural connective tissue is missing in cases with tumorous infiltration of the pleura. Continuous fibroblast activation, e.g., by macrophage or foreign-body giant-cell-released mediators, seems to be the decisive factor in the fibrosing process. No therapy-related tumor growth alterations could be demonstrated.

Chronic bronchitis--alterations of the bronchial mucosa

The mucociliary transport system is usually an important defense system which protects the body against a variety of noxious agents. Reactions of the bronchial mucosa to chronic infections are seen in the ciliated cells, the amount of globlet cells, in modifications of the basement membrane underlying the bronchial epithelium and an altered percentage of inflammatory cells. In ciliated cells the following atypia can be seen: thickening of the ciliar membrane, swollen cilia, formation of compound cilia, disarrangement of microtubules. Common alterations of the basement membrane are: increased diameter of the basement membrane zone, inhomogeneous staining pattern of the basement membrane zone, formation of cytoplasmatic protrusions, formation of double layers of the basement membrane and increased number of cytoplasmatic bound vesicles. Structural abnormalities of the basement membrane will lead to disturbances of the zone of transition and have to be interpreted as a sign of disregulation in the process of diffusion and resorption. The inflammatory response of the epithelium during chronic bronchitis and asthma shows many similarities. The bronchial epithelium has a specific reaction pattern which supports the response against different noxious agents. So all findings have to be interpreted as unspecific pathological changes. All alterations may show different degrees of severity and are dependent on individual pattern and the severity of chronic process. Electronmicroscopical examinations in combination with lightmicroscopical findings and immuno-histochemistry and seen in context with clinical data help to understand the mechanism of the inflammatory process.

Lung cancer risk and welding: results from a case-control study in Germany

In a case-control study, 839 male hospital-based cases of primary lung cancer and the same number of population-based controls--matched by sex, age, and region of residence--were personally interviewed for their job and smoking histories. The study allows to quantify occupational asbestos exposure that was thought to be a welding-associated risk: 6% of cases and 2% of controls were classified into the occupational category "welders or burners# (odds ratio [OR] = 2.65). This OR was reduced to 1.93 (95% confidence limit [CL]: 1.03-3.61) after adjustment for smoking and asbestos. In contrast, a history of welding in general for at least a half-year is 28% among cases and 23% among controls, yielding an OR of 1.25 (95% CL: 0.94-1.65) after adjustment for both confounders. The OR of welding for more than 6,000 hr is 1.45 (95% CL = 1.04-2.02), reduced to 1.10 after adjustment for smoking and asbestos. Oxyacetylene welding for more than 6,000 hr lifelong is associated with an OR of 1.86 (95% CL = 1.01-3.43) reduced to 1.46 (n.s.) after adjustment for smoking and asbestos. The risk of oxyacetylene welding seems to be highest for oat cell carcinoma with an adjusted OR for ever-exposure of 1.46 (95% CL = 0.69-3.10). Therefore, the present study supports the hypothesis that some, but not all, of the excess risk of welders observed in the literature may be due to a history of cigarette smoking and occupational asbestos exposure. The elevated risk for the subgroup of employees in the aircraft industry reported for the midterm evaluation of the study still prevails, though no longer statistically significant. However, employees in this industry who ever welded show an OR of 2.29 (95% CL = 1.19-4.42) after adjustment for smoking and asbestos.

Expression of c-Met receptor and hepatocyte growth factor/scatter factor in synovial sarcoma and epithelioid sarcoma

Overexpression of c-Met receptor/hepatocyte growth factor (scatter factor) system (c-Met/HGF/SF) as a physiologically paracrine cellular signaling system is thought to be involved in the progression of malignant tumours. In 26 synovial sarcomas and epithelioid sarcomas, c-Met and HGF/SF expression was analysed immunohistochemically. There were 10 biphasic synovial sarcomas, 7 of which showed moderate to strong c-Met expression in epithelial areas compared with the fibrous component, with corresponding expression of HGF/SF. Six of 9 monophasic fibrous synovial sarcomas showed only very faint c-Met and corresponding HGF/SF expression. In 7 epithelioid sarcomas strong expression of c-Met and HGF/SF was observed within epithelioid tumour cells. Non-radioactive in situ hybridization demonstrated the synthesis of c-Met receptor in tumor cells by detecting c-met-mRNA. This analysis shows that in synovial sarcomas and epithelioid sarcomas, tumour entities with epithelial and mesenchymal structures, c-Met and HGF/SF overexpression can be detected, indicating a role of this signaling system in these subtypes of sarcoma, and especially in the more epithelioid tumour phenotype. An autocrine interaction between overexpressed c-Met receptor and HGF/SF may be hypothesized.

Exposure to carbon black: a cancer risk?

Lung cancer is one of the most serious health problems in the industrial nations and is therefore of great public and scientific interest. Although inhalative cigarette smoking is without doubt the main cause for the increasing frequency of lung cancer, during recent years there has been more and more public interest in other substances in the environment or at the work place that are assumed to be potentially carcinogenic especially due to experiences with fibrous particles such as asbestos and their effects. Enhanced attention is also directed to inert or nuisance dusts such as carbon black. Evaluation of the possibly increased risk for humans should first be based on exact epidemiology data. In the absence of those data--as in the case of carbon black--experimental data in animals serve as the point of orientation, especially results gained in rats in long-term inhalation studies. Pathologic anatomy investigations of human lungs under similar exposure conditions, however, render results quite different from those obtained in rats and, thus, preclude ready interpretation of animal results to human risk assessment. This is particularly true for the development of lung tumors in rats under overload conditions as well as for certain tumor types not observed in human lung tissues. It is therefore quite understandable that many researchers propose to interpret the changes observed in rat lung tissues after inhalation of carbon black as rat-specific reaction mechanisms that cannot be applied to human tissues, which in the past have led to the wrong conclusions regarding human risk assessment due, among other factors, to incorrect experimental design and inaccurate nomenclature of tumorous lesions in rats.

[Basic principles of LIFE--autofluorescence bronchoscopy. Results of 194 examinations in comparison with standard procedures for early detection of bronchial carcinoma--overview]

BACKGROUND

Conventional bronchoscopy in the identification of preneoplasias and carcinoma in situ (CIS) has been inadequate to date. Tissue autofluorescence was found to differentiate normal mucosa from dysplastic or carcinomatous bronchial mucosa. This principle resulted in the development of the LIFE System (Light Imaging Fluorescence Endoscope, Xillix Techn., Vancouver, BC), now in routine use worldwide at 35 centres. In a prospective multicentric study in North America the relative sensitivity for diagnosing intraepithelial neoplasias of combined white light (WLB) and LIFE bronchoscopy in 173 at-risk patients was 6.3 as compared to WLB alone. A similar European multicentric study will be completed by spring of 1998.

PATIENTS AND RESULTS

We report on our experience with the routine use of the LIFE System over 23 months. 194 examinations (165 patients) were performed. Moderate to severe dysplasias and in situ carcinomas were diagnosed with a relative sensitivity of 2.7 by the combined WLB-LIFE examination as compared to WLB alone.

CONCLUSION

Autofluorescence bronchoscopy as a routine investigation without need of photosensitizers in patients with a high risk for lung cancer can lead to a substantial increase in the detection rate of CIS and moderate to severe dysplasias compared to white light bronchoscopy alone.

[Placentoid malformation of the lung]

The differential diagnosis of bullous and cystiform lung alterations comprises a relatively calculable number of various diseases, in which the most important are rare cystic tumors and congenial malformations, such as adenomatoid cystic malformation. We report on a rare clinical picture. In this case, the clinical diagnosis of localized unilateral emphysema caused by local displacement and with subsequent complications had led to "bullectomies" and pneumonectomy. Macroscopically, spongiform solid areas in association with areas of physaliform transformation were seen, corresponding histomorphologically to villous, placentalike formations. The "villous stroma" revealed focally regressive alterations, fatty islets and leiomyomatous areas. So far, the pathogenesis of this lesion, described as "placentoid malformation" due to its pathognomonic histological appearance, remains unclear. In contradiction to the much discussed hypothesis that this lesion may develop from pre-existing lung emphysema, our results suggest that this may be an independent lesion, possibly congenital hamartous malformation with self-developing progression. The clinically predominant emphysematic alterations are considered to be caused by a valve mechanism due to unphysiological traction forces, the lymphatic pathways regularly found in the border areas towards the original lung tissue, possibly playing an important etiological part.

The first constant domain (C(H)1 and C(L)) of an antibody used as heterodimerization domain for bispecific miniantibodies

Bispecific miniantibodies were constructed by genetically fusing the C(H)1 domain of an IgG1 to the C-terminus of a single-chain Fv fragment (scFv-425), specific for the EGF receptor, and fusing the C(L) domain of a kappa light chain to the C-terminus of a scFv specific for CD2 (scFv-M1). An efficient dicistronic gene arrangement for functional expression in Escherichia coli was constructed. Immunoblots demonstrated correct domain assembly and the formation of the natural C(H)1-C(L) disulfide bridge. Gel filtration confirmed the correct size, sandwich ELISAs demonstrated bispecific functionality, and SPR biosensor measurements determined binding to EGF-R in comparison to bivalent constructs. Bispecific anti-EGF-R/anti-CD2 miniantibodies are candidates for the immunotherapy of cancer.

Expression and localization of vascular endothelial growth factor and its receptor flt in pulmonary sarcoidosis

Vascular endothelial growth factor (VEGF) is a multifunctional cytokine, which has recently been reported to enhance the activation and migration of monocytes through the flt receptor in vitro, which are key events in granuloma formation of granulomatous disorders and in sarcoidosis. Since activated macrophages and monocytes are known to be involved in sarcoid granuloma formation in sarcoidosis, we investigated the expression of VEGF and its receptor flt in 33 paraffin-embedded lung tissue biopsies of patients with pulmonary sarcoidosis. VEGF-mRNA was localized by nonradioactive in situ hybridization, VEGF and flt expression were visualized immunohistochemically. We found an increased transcription and protein production of VEGF and an overexpression of flt in activated alveolar macrophages, in epitheloid cells, and in multinuclear giant cells of pulmonary sarcoid granulomas.

Hyperventilation induces release of cytokines from perfused mouse lung

Artificial mechanical ventilation represents a major cause of iatrogenic lung damage in intensive care. It is largely unknown which mediators, if any, contribute to the onset of such complications. We investigated whether stress caused by artificial mechanical ventilation leads to induction, synthesis, and release of cytokines or eicosanoids from lung tissue. We used the isolated perfused and ventilated mouse lung where frequent perfusate sampling allows determination of mediator release into the perfusate. Hyperventilation was executed with either negative (NPV) or positive pressure ventilation (PPV) at a transpulmonary pressure that was increased 2.5-fold above normal. Both modes of hyperventilation resulted in an approximately 1.75-fold increased expression of tumor necrosis factor alpha (TNFalpha) and interleukin-6 (IL-6) mRNA, but not of cyclooxygenase-2 mRNA. After switching to hyperventilation, prostacyclin release into the perfusate increased almost instantaneously from 19 +/- 17 pg/min to 230 +/- 160 pg/min (PPV) or 115 +/- 87 pg/min (NPV). The enhancement in TNFalpha and IL-6 production developed more slowly. In control lungs after 150 min of perfusion and ventilation, TNFalpha and IL-6 production was 23 +/- 20 pg/min and 330 +/- 210 pg/min, respectively. In lungs hyperventilated for 150 min, TNFalpha and IL-6 production were increased to 287 +/- 180 pg/min and more than 1,000 pg/min, respectively. We conclude that artificial ventilation might cause pulmonary and systemic adverse reactions by inducing the release of mediators into the circulation.

[Structural analysis of 16 different coronary stent systems]

Parallel with the increasing number of coronary stent implantation procedures, new or more elaborate coronary stents were introduced into clinical use almost every month in 1996. We have studied the architecture, surface-morphology, and shape-conversion of 16 different coronary stent systems. The objective of our study was to detect possible specific design and surface features which might influence the healing process in stent restenosis and stent thrombosis. Using electron microscopy we found ultrasmooth surfaces on 5 stents. All other coronary stents revealed individually varying and partly sharp-edged surface irregularities. Video-based morphometry showed covering between 8.3% and 26.4%. Stent shortening after in-vitro expansion ranged from 0% up to 10.5% of the initial stent length. In some stent systems balloon dilation lead to over-expansion of the stent margin. This over-expansion amounted up to 20% of the balloon diameter and the stents revealed a rather biconcave than homogeneous expansion pattern. This phenomenon was also found after postmortal stent implantation in 20 autopsied hearts.

[Correlation of radiologic and pathologic-anatomical findings in dust-induced pneumoconiosis in former coal miners]

The ILO classification of small and large opacities is the basis for the compensation of patients with pneumoconiosis. In order to validate the radiological findings, we compared the ILO classification with the gradings of pneumoconiosis in the post mortem investigation (n = 126). An ILO classification of 1/0 used as the threshold value for accepting the diagnosis of a pneumoconiosis was 100% sensitive with a specificity of 2%. With a value of 2/3 the sensitivity decreased to 60% and specificity increased to 74%. The grading of large opacities in the radiograph correlated well with the post mortem findings (rs = 0.71; p < 0.001). For accepting the diagnosis pneumoconiosis from the radiograph alone a threshold value of 1/0 is not specific. The ROC-plot revealed that specificity reached acceptable levels with an ILO classification of at least 2/3.

The relation between various histological types of lung cancer and the number of years since cessation of smoking

We studied the relation between various histological types of lung cancer and the number of years of cessation from smoking using data from a recently completed case-control study in Northern Germany. In this context we wanted to answer the question whether smoking cessation is a specific symptom of small cell lung cancer. Defining current smokers as the reference group the odds ratios decreased with years of cessation. Based on the analysis of all male cases and controls in our study, former smokers who stopped smoking 6-10 years ago had an odds ratio of 0.97 (95% confidence interval (C.I.) = 0.65-1.45), ex-smokers with 11-20 years of smoking cessation had a reduced risk of 0.55 (95% C.I. = 0.38-0.79), and for more than 20 years of cessation we found an odds ratio of 0.25 (95% C.I. = 0.16-0.40). Moreover, these calculations are also presented for the major groups of histological types of lung cancer. Our data show that there is no evidence for the presumption that cases with small cell lung cancer stop smoking earlier than cases with other histological types: in no other histological category we found such a big part of current smokers.

Tumour regression in non-small-cell lung cancer following neoadjuvant therapy. Histological assessment

In the scope of a prospective multi-centre study after neoadjuvant combined chemotherapy (carboplatin, ifosfamide, etoposide, vindesine) and radiotherapy (45 Gy) 40 resection specimens of locally advanced non-small-cell lung cancer were analysed in order to establish reproducible pathological/anatomical results of tumour regression. Resection specimens of 28 squamous cell carcinomas and 12 adenocarcinomas were investigated using serial sections of the primary lesion. The mean age of the patients was 57 years. The results were compared to spontaneous regressive changes in a control group of 50 untreated non-small-cell lung cancers. Marked scarry fibrosis in the region of the former primary tumour, concentric foci of fresh tumour necroses and surrounding foam cell clusters with transition into vascular granulation tissue could be established as characteristic features of therapy-induced tumour regression, whereas untreated carcinomas revealed necroses with adjoining vital tumour tissue. Using a three-step regression system, 3 tumours could be classified as grade I (no or only slight tumour regression), 10 tumours as grade IIA (marked but incomplete tumour regression, more than 10% vital tumour tissue), 20 tumours as grade IIB (less than 10% vital tumour tissue) and 7 tumours as grade III (complete tumour regression without vital tumour tissue). After a median follow-up period of 32.3 months in patients with grade IIB or III tumour regression ("responders") the median survival time of 27.9 months was found to be significantly longer than in patients with grade I or IIA tumour regression ("non-responders") with a median survival period of 13.7 months (log-rank test, P = 0.020). The resection specimens analysed, which were obtained 7 weeks (on average) after the end of radiochemotherapy, did not show specific changes due to preoperative therapy, but quite characteristic histological alterations in the former tumour area were registered, which had been induced by combined neoadjuvant radiation and chemotherapy. The grade of therapy-induced tumour regression could be shown to be a significant prognostic factor in non-small-cell lung cancer.

[Intravascular ultrasound findings in calcifying arteriosclerosis: in vitro validation using "soft" roentgen images]

AIM

The aim of this study was to validate the detection of calcified arteriosclerotic plaques with intravascular ultrasound (IVUS).

METHOD

181 arteries were examined by 20/30 MHz IVUS. The ultrasound cross-sections were compared to the corresponding radiologic (30 kV) and histologic cross-sections.

RESULTS

Calcified lesions were imaged as bright echos with shadowing. In 13 cases of 161 calcified lesions were too small to detect by IVUS. In 5 ultrasonic sections the diagnosis "calcified lesion" could not be verified neither by radiology nor by histology. The sensitivity was 91.6%, the specificity was 94.7% and the accuracy was 93.0%.

CONCLUSIONS

Because of the acoustic properties of calcium, calcified lesions can be detected accurately by IVUS. IVUS can generate new insights into the effect of plaque composition on the response to catheter therapies.

[Lymphomatoid granulomatosis--remission induction with interferon-alpha 2b]

HISTORY AND ADMISSION FINDINGS

A 72-year-old woman was admitted to hospital because of nonproductive cough, acrodistal sensorimotor axonal polyneuropathy, fatigue and 10 kg weight loss over the preceding 9 months.

INVESTIGATIONS

Chest radiogram showed multiple round foci in both lungs. No organs other than the lungs and the peripheral nervous system were affected. Open lung biopsy revealed a pleomorphic angioinvasive lymphocytic infiltrations.

DIAGNOSIS, TREATMENT AND COURSE

The findings indicated lymphomatoid granulomatosis (LG). Wegener granulomatosis was excluded on the basis of the clinical, serological and histopathological findings. Treatment with alpha-interferon (IFN-alpha) produced complete remission within 4 months. Interruption of treatment immediately resulted in a recurrence.

CONCLUSION

Together with previously reported cases this patient's response to IFN-alpha suggests that IFN-alpha is a less toxic alternative to cyclophosphamide and corticosteroid administration in the early stages of LG.

[Discontinuous lymph node metastases ("skipping") in malignant lung tumors]

In 50 lung cancers (25 small cell lung cancers, 17 squamous cell carcinomas, 8 adenocarcinomas) pulmonary, mediastinal and cervical lymph node-metastases were analyzed. Lymph-node "skipping" was demonstrated in 46% of the investigated tumors. In seven of these cases the lymph nodes were skipped, which showed complete hyalinization as a consequence of preexisting anthracosilicosis. In 5 other tumors additional lymph nodes with preserved structure were skipped by the metastatic process. Fibrosis of lymphatic tissue after tuberculosis or exposure to ionizing radiation were further reasons for lymph-node skipping. The skipping of intact lymph nodes can be explained by anatomically demonstrable intra- and perinodal short circuit connections. Apart from that, preexisting lymph node changes (silicosis, fibrosis) play an important part.

[Placentoid malformation of the lung as differential diagnosis of localized emphysema]

In a 50-year old patient with a long history of chronic obstructive airway disease and pulmonary emphysema, unusual solid spongious areas adjacent to bullous tissue were detected by bullectomia because of mediastinal displacement and dyspnoea on exertion. Pathological anatomical diagnosis showed villous framework in the marginal regions of bullous transformed parenchyma. According to pathognomonic histological finding the lesion is known as placentoid malformation or placentoid bullous transmogrification, respectively. This disease must be differentiated against rare cystic tumours such as alveolar adenoma or sclerosing haemangioma as well as congenital lesions e.g. adenomatoid cystic malformation. The lesion presented here includes hamartomatous features, such as the presence of leiomyomatoid proliferations of smooth muscle cells and fatty tissue embedded in the villous stroma. The clinically predominant emphysematous transformation of the adjacent lung tissue is pathogenetically the result of a valve formation in combination with unphysiological traction forces. The ectatic lymphatic vessels in peripheral tissue may perhaps be of etiological importance. According to former studies this may be an congenital malformation with progressive development. Resection of affected lung parenchyma seems to be curative: so far, no recurrences have been noticed.

[Heart rupture after mitral valve replacement. Pathologic-anatomic findings]

The rupture of the free left ventricular wall is considered a serious complication following mitral valve replacement. We report about 3 cases characterized by similar pathologic-anatomical findings within the region of the left ventricle after mitral valve replacement. Following resection of the original and pathologically altered mitral valve and implantation of a prosthesis, rupture of the left ventricular wall occurred in short time intervals ranging from 1 to 12 h postoperatively. All cases represented a transverse midventricular disruption located between the mitral valve anulus and the resected papillary muscles. The histologic findings included necrotic, damaged myocardial structures with considerable bleeding to the interstitium. Inflammatory infiltration could be detected within the myocardial defects. Abnormal pathologic findings of the coronary arteries or intraoperative lesions could be excluded by thorough autoptic studies. Because of central localization of the ventricular disruption between the mitral valve anulus and the papillary muscles a direct traumatic myocardial injury caused by mitral valve orotheses is to be excluded. When taking into account several reports from literature in combination with our described findings, in autopsy, a loss of contractile integrity of the left ventricle following resection of mitral valve apparatus, especially the chordae tendinaea, should be considered as primary cause for this type of ventricular rupture. This destabilization will lead to a regionally stressec myocardial "stretching" which finally results in rupture of the left ventricular free wall. The described pathogenetic concept seemingly represents the decisive mechanism of this transverse midventricular disruption in all 3 cases. To prevent such post-operative complications, only very limited resection of the mitral valve apparatus should be performed to maintain parts of the chordae tendineae.