Nonstoichiometric defects in carbides of the Group IV and V transition metals and radiation-induced atomic defects in SiC were studied by positron lifetime measurements before and after low-temperature (80 K) electron irradiation and subsequent thermal annealing up to 1900 K. Agglomeration of radiation-induced atomic defects which strongly depends on the energy of the irradiation electrons and subsequent decay of the agglomerates in SiC is observed.

Commenting on a case report of dermal immunocytoma with crystal-storing histiocytes, a short review is given on the phenomena related to crystallization of monoclonal immunoglobulins within plasma cells, in the extracellular space, or within the lysosomal compartment of macrophages. Paraprotein crystallization is supported by hydrophobicity, poor solubility in the cold or at acid pH, and there are few reports on structural defects of crystal-forming myeloma proteins which are supposed to promote either their crystallization or impaired intralysosomal degradation. In the hitherto known cases of crystal histiocytosis, immunoglobulins of light chain type kappa have been exclusively involved in the process of macrophage storage. Accumulation of paraprotein-related crystals in macrophages may mimic the appearance of Gaucher cells or of the so-called pseudo-Gaucher cells seen in chronic myelogeneous leukaemia. With regard to their lightmicroscopical and ultrastructural differences to both, Gaucher cells and pseudo-Gaucher cells, paraproteinaemia-related crystal-storing macrophages may be denoted as pseudo-pseudo-Gaucher cells (PPGC). Human PPGC are similar to constitutive crystal-storing histiocytes known from inbred C57 BL-6 mice. The distribution of PPGC may be limited to the realm of a plasmacytoma or immunocytoma, but there are also cases with systemic involvement of the RES similar to Gaucher disease.

The Institute of Pathology deals with more than 36.000 histological, cytological and autoptic reports each year. Furthermore it has to accomplish quite different tasks like patient care, research, teaching, management and tumor registry. Computers are used in all these fields. Thus the Institute a baseline organisation system for pathology has been installed since 1988. This system runs now for more than two years with any serious trouble like hardware failures or lost reports or inconsistency of the database. The system is upgraded to a large system with more than 60 terminals this year. PATSY software is written completely in MUMPS and supports all necessary tasks of the Institute. This paper describes the structure of the hardware and software in detail and discusses the advantages of our solution with regard to other published papers dealing with organisation systems for pathology.

Tumor necrosis factor (TNF) has been shown to mediate lipopolysaccharide-induced neutrophil adhesion to liver sinusoidal endothelium in vivo. Female NMRI mice received either 5 μg lipopolysaccharide (R595) per animal alone (model A) or together with 116 μmol d-galactosamine (model B). One hour after injection, TNF activity in the serum was detectable to an equal extent in both models. Neutrophils in the liver, which had been identified by chloroacetate esterase staining of liver sections and quantitated by light microscopy, started to increase at 1 h and were elevated 10-fold above baseline at 6 h after application in (A) and (B). If 0.5 μg TNF instead of lipopolysaccharide was injected alone (model C) or together with d-galactosamine (model D), neutrophil influx into the liver was comparable to that observed in (A) or (B). Alanine aminotransferase activity in the serum was nearly normal in (A) and (C) 6 h after injection, while it reached levels up to 50-fold above baseline in models (B) and (D). This reflects the well-known d-galactosamine sensitization against lipopolysaccharide or TNF. Furthermore, degranulation of a large number of intrasinusoidal neutrophils could be observed 9 h after lipopolysaccharide-galactosamine injection. The administration of 116 μmol d-galactosamine per animal alone led neither to a measurable TNF activity in the serum nor to an increase in alanine aminotransferase activity or number of liver neutrophils. If the animals had received 50 μl turpentine subcutaneously 24 h prior to lipopolysaccharide, TNF or d-galactosamine injection, the induced acute-phase reaction suppressed the increase of liver neutrophils in all models. Acute-phase reaction also prevented neutrophil degranulation and the rise of alanine aminotransferase in (B) to a great extent, while serum TNF activity was only minimally affected. It is concluded that TNF mediates neutrophil adhesion to the sinusoidal endothelium in vivo and that acute-phase reactants prevent lipopolysaccharide- or TNF-induced neutrophil influx into the liver.

Beta-glucuronidase and N-AS-D-chloroacetate esterase cytochemistry have been applied to rat liver sinusoidal endothelial cells and Kupffer cells. Both staining procedures allowed a clear-cut differentiation of either cell type. Kupffer cells which had been stained with beta-glucuronidase showed a positive reaction, whereas sinusoidal endothelial cells were completely negative. If the chloroacetate reaction was used, the former stained diffusely while the latter showed a characteristic granular staining pattern. Identity and purity of sinusoidal endothelial cells and Kupffer cells was validated by transmission and scanning electron microscopy as well as by the pattern of released eicosanoids which is characteristic for either cell type. These two staining techniques are a valuable addition to the peroxidase reaction commonly applied for differentiation.

Sinusoidal endothelial cells were isolated by collagenase-pronase digestion of rat livers followed by centrifugal elutriation. The main endothelial cell fraction consisted of more than 85% endothelial cells as shown by electron microscopy and enzyme histochemistry. Contamination by Kupffer cells was less than 5%. The endothelial cells formed a coherent stable monolayer on dishes coated with collagen type IV in the presence of an RPMI 1640 medium supplemented with 4% Ultroser. Fc receptors were undetectable immediately after elutriation but reappeared after 12 h in culture. Von Willebrand factor (formerly factor VIII-related antigen) could not be detected unequivocally by immunofluorescence. Unchallenged endothelial cells did not produce eicosanoids. In the presence of free arachidonate, however, prostaglandins D2 and E2 as well as thromboxane B2 and 6-keto-prostaglandin F1a were detected by radioimmunoassay and by high-performance liquid chromatography analysis of [3H]arachidonate-exposed cells. Cells treated with the Ca2+ ionophore A23187 produced the same spectrum of immunologically measured prostanoids. In contrast to Kupffer cells in primary culture, eicosanoid formation by endothelial cells was neither triggered by phagocytotic stimuli nor suppressed by pretreatment with dexamethasone.

A slow-positron source has been installed in the therminal of an electrostatic 6.5 MeV accelerator and provides a monoenergetic positron beam in the few-MeV range. It will be used to operate a “fast” positron lifetime spectrometer based onβ+γ coincidences. The properties of the beam, the expected performance of the spectrometer, its advantages over conventionalγγ lifetime measurements, a number of intended applications, as well as recent positron-electron scattering experiments and plans for positron channelling and channelling-radiation studies are outlined.

Using the cytochemical demonstration of alkaline phosphatase (AP) two different populations of lymphocytes are seen in the short-tailed mouse Clethrionomys glareolus: AP-positive and PA-negative lymphocytes. The aim of this study was to find out as to whether in this species AP represents a cytochemical marker for differentiating T- and B-lymphocytes. For this purpose, we analysed the frequency of AP-positive lymphocytes in the peripheral blood, bone marrow, thymus, lymph node, spleen, and Peyer's patches of normal adult animals 3 months after neonatal thymectomy, and at varying times following administration of intraperitoneal injections of a maximum dose of 16-methylenprednisolone. In normal mice the frequency of AP-positive lymphocytes in peripheral blood and bone marrow corresponds to that of T-lymphocytes in other species. In the thymic cortex, nearly 100% of the lymphocytes show an AP-positive reaction. In the peripheral lymphatic organs these cells are prevailing in the T-dependent areas (paracortex of lymph node, periarteriolar lymph sheet of spleen, and serosa-near region of Peyer's patches). Neonatal thymectomy as well as administration of corticosteroid cause a significant loss of enzyme-positive lymphocytes in the organism. This T-cell reduction becomes particularly evident in B-dependent regions, because in these areas AP-positive (T-) and AP-negative (B-) cells are usually intermingled, and this provides the necessary condition of T/B-interaction, which is of immunological significance. In T-dependent zones, populated mainly by AP-positive cells, neonatal thymectomy results in overall atrophy, while T-cell depletion, expressed as a percentage, is less pronounced within these atrophied areas. Based on these findings the conclusion may be drawn that in Clethrionomys glareolus committed thymocytes, recirculating T-lymphocytes as well as T-helper cells show an AP-positive reaction in contrast to prethymic T-cells, T-suppressor cells and B-cells, which do not express this enzyme. The histochemical demonstration of lymphocytic AP therefore permits an easy visualisation and quantification of T-lymphocytes in Clethrionomys glareolus.

Thirty-seven patients with chronic cytopenia were studied using a CFU-c assay in agar. On the basis of the growth pattern three types of preleukaemic syndrome (PL) and two types of aplastic anaemia were distinguished. Further evaluation of the bone marrow dysfunction was attempted with a combined application of cytochemistry and electron microscopy for the morphologic study of cells proliferating in vitro. Well-defined maturation defects in the growing cells from the bone marrow of patients with PL were demonstrated with cytochemical stainings performed in agar. These results were supported by electron microscopic findings of Auer-body-like inclusions in "statu nascendi" in the vacuoles of preleukaemic cells. On the basis of our results a high risk group of PL for development of overt leukaemia and a group of patients with a grave prognosis in aplastic anaemia were distinguished. The data obtained are relevant for the clinical diagnosis and prognosis of patients with cytopenias.

Pathophysiological Aspects.- Current View of the Mononuclear Phagocyte System.- The Kinetics of Mononuclear Phagocytes in Man.- Biochemical Properties of Human and Murine Mononuclear Phagocytes and Their Changes on Activation.- Macrophages in the Regulation of Immunity.- The Role of Macrophages as Effector Cells.- The Macrophage as a Cytotoxic Effector Cell.- The Role of Complement in the Function of the Monocyte-Macrophage System.- Macrophage-Dependent Production of Erythropoietin and Colony-Stimulating Factor.- The Relation Between Monocytes and Resident (Tissue) Macrophages.- Development of Exudate-Resident Macrophages in Vivo and in Vitro.- The Monocyte-Macrophage System in Granulomatous Inflammation.- Macrophages in Granulomas: Histochemical Evidence Suggesting Local Control of Heterogeneous Functions.- The Role of Macrophages in Storage Diseases.- Interaction of Lipoproteins with Macrophages.- The Role of Macrophages in Atherosclerosis.- Clinical Syndromes.- Acute Monocytic Leukemias.- Subacute and Chronic Myelomonocytic Leukemia.- Lysosomal Granules in Leukemic Monocytes and Their Relation to Maturation Stages.- Characteristics and Functions of Monocytes and Promonocytes in Monocytic Leukemia.- Chronic Monocytic Leukemias.- Therapy of Acute Monoblastic Leukemia.- Histiocytic Medullary Reticulosis - Neoplastic or Atypical Inflammatory Process?.- Histiocytic Medullary Reticulosis Re-visited.- Therapy of Malignant Histiocytosis.- Immunohistochemical Marking of Malignant Fibrous Histiocytoma and Malignant Histiocytosis.- Malignant Histiocytic Disorders of the Skin.- Childhood Histiocytosis X, Clinical Aspects and Therapeutic Approaches.- Therapy in Pulmonary Histiocytosis X.- Sinus Histiocytosis with Massive Lymphadenopathy and Epidural Involvement.- Familial Lymphohistiocytosis.- Concluding Remarks: The Pathology of the MMS-Present Knowledge and Future Trends.

After tensile and torsional deformation of a high-purity Ta crystal the internal friction was measured between 70K and 300K in a torsion pendulum at 0.7Hz and at 34Hz. The spectrum (0.7Hz) can be decomposed into a main maximum α1 at 150K and two satellites α2 and α3. They are discussed in terms of kink-pair formation in non-screw dislocations and kink diffusion on dislocations. The sensitivity of the peaks to torsional deformation and the additional amplitude-dependent internal friction is compared to earlier results on Nb.

Tangier disease is a rare hereditary disorder characterized by the virtual absence of normal high density lipoproteins (HDL) from plasma and widespread tissue accumulation of cholesteryl esters, mostly cholesteryl oleate(Assmann 1979; Herbert et al. 1978a). Prominent clinical features include enlarged, orange- yellow tonsils, splenomegaly and, frequently, peripheral neuropathy; early atherosclerosis is not a manifestation of the disease. Histological and ultrastructural observations have provided evidence that the intracellular lipid storage is mainly confined to macrophages (tissue histiocytes), Schwann cells of peripheral nerves and myenteric plexus, nonvascular smooth muscle cells of the intestine, nevus cells and, occasionally, mast cells and fibroblasts. Endothelial cells and smooth muscle cells of large and small arteries are not affected by lipid storage. The tissue macrophage is the site of most of the lipid deposition, and the conversion of histiocytic cells to foam cells is the predominant abnormality in affected tissues. The foam cells contain sudanophilic, cytoplasmic lipid droplets and, upon occasion, crystalline material; on examination at room temperature in plane polarized light, the storage material is birefringent and partially exhibits a maltese cross pattern. At body temperature a large proportion of the cholesteryl ester droplets within foam cells are in the smectic liquid crystalline state (Katz et al. 1977). Two major mechanisms may account for the intracellular accumulation of cholesteryl esters in various tissues: phagocytosis of abnormal lipoproteins and/or ineffective removal of cholesterol from cells. These two mechanisms are discussed in the light of present biochemical and morphological evidence.

A synopsis is given of recent attempts to clarify the nature of the prominent resistivity recovery stage at 220 K (Stage III) in irradiated high-purity α-iron and of the related magnetic and mechanical relaxation processes. With increasing irradiation dose the height of this stage increases linearly, and its position shifts to lower temperatures according to a second-order reaction. In accord with other experimental results this is taken as evidence for free migration of an elementary point defect in iron at about 220 K. Since vacancy migration can be excluded on the basis of thermal-equilibrium measurements, Stage III is attributed to interstitial migration. Suggestions for the interpretation of the Stage-III relaxation phenomena are presented. Es wird über neueste Untersuchungen an bestrahltem hochreinem α-Eisen berichtet, die durchgeführt wurden, um die Vorgänge in der ausgeprägten Erholungsstufe des elektrischen Widerstandes bei 220 K (Stufe III) und die in diesem Temperaturbereich auftretenden magnetischen und mechanischen Relaxationsprozesse aufzuklären. Mit wachsender Bestrahlungsdosis wächst Stufe III linear an und verschiebt sich zu tieferen Temperaturen gemäß einer Reaktion zweiter Ordnung. Daraus wird geschlossen, daß in Eisen bei ungefähr 220 K eine elementare atomare Fehlstelle frei wandert. Da Leerstellenwanderung aufgrund von Messungen im thermischen Gleichgewicht ausgeschlossen werden kann, wird Stufe III der freien Wanderung von Zwischengitteratomen zugeschrieben. Deutungsmöglichkeiten der Relaxationserscheinungen im Bereich der Stufe III werden vorgeschlagen.