Identification of benzothiazoles as potential polyglutamine aggregation inhibitors of Huntington's disease by using an automated filter retardation assay

Preventing the formation of insoluble polyglutamine containing protein aggregates in neurons may represent an attractive therapeutic strategy to ameliorate Huntington's disease (HD). Therefore, the ability to screen for small molecules that suppress the self-assembly of huntingtin would have potential clinical and significant research applications. We have developed an automated filter retardation assay for the rapid identification of chemical compounds that prevent HD exon 1 protein aggregation in vitro. Using this method, a total of 25 benzothiazole derivatives that inhibit huntingtin fibrillogenesis in a dose-dependent manner were discovered from a library of approximately 184,000 small molecules. The results obtained by the filter assay were confirmed by immunoblotting, electron microscopy, and mass spectrometry. Furthermore, cell culture studies revealed that 2-amino-4,7-dimethyl-benzothiazol-6-ol, a chemical compound similar to riluzole, significantly inhibits HD exon 1 aggregation in vivo. These findings may provide the basis for a new therapeutic approach to prevent the accumulation of insoluble protein aggregates in Huntington's disease and related glutamine repeat disorders.

[Scanning electron microscopy and elementary analytic studies of osteosarcoma]

By scanning electron microscopical (SEM) screening analyses of 14 osteosarcomas characteristic three-dimensional structures of tumor osteoid could be demonstrated. These osteoid formations are highly characteristic for osteosarcoma; we did not find them at any other bone tumor or tumor like lesion until now. With these results a better understanding of characteristic growth patterns of bone tumors could be achieved by SEM. No specific results could be found by elementar analysis, x-ray microanalysis, x-ray fluorescence and x-ray diffractometer techniques. The significance of single interesting values has to be evaluated in the future.

Mineralization of human aortas with coarctation: quantitative electron probe microanalysis

Aortas with coarctation (isthmus stenosis) are obviously an ideal model to investigate pressure dependent changes of the aorta, as one can compare the proximal region (high pressure) with the distal region (low pressure). 7 aortas of patients aged from 2 months to 54 years were investigated. The concentrations of Na, Mg, P, S, C1, K, and Ca were determined by electronprobe microanalysis. Ca and P are constituent parts of the developing mineral and are mainly discussed. The Ca/P ratio (by weight) is about 0.3 in the unmineralized and about 2 in the mineralized tissue. Mineralization is demonstrated by a parallel increase of Ca, P, and the Ca/P ratio. Enrichments of Ca and P are found above all in a subintimal band. Usually they occur proximally and distally, but are much more pronounced proximally. Even in the aorta of a 2 month old infant enrichments were found proximally, but not distally. Thus mineral deposits occur very early in regions of hypertension. The differences between the proximal and distal region may demonstrate the influence of blood pressure on vascular mineralization. The mineralization starts in small compartments, which increase in size and number in the process of mineralization. Mineralized regions could often be localized by cathodoluminescence. But to demonstrate and localize the initial mineral deposits and to quantify element contents, electronprobe microanalysis became indispensable.

Investigations on vasogenic and cytotoxic brain edema, comparing results from X-ray microanalysis and flame photometry

In these studies vasogenic brain edema has been induced by implantation of rat glioma cells RGI 2.2 into BD-IX rats while cytotoxic edema pas produced by permanent regional ischemia in the mongolian gerbil. In the gerbil sodium concentration was raised from 201 meq/kg d.w. (dry weight) [p/b (peak/background) = 0] to 269 meq/kg d.w. (p/b = 0.25; 2 hours) and 651 meq/kg d.w. [p/b = 0.71; 24 hours), whereas potassium concentration decreased from 373 meq/kg d.w. (p/b = 1.69) to 337 meq/kg d.w. (p/b = 1.65) and 152 meq/kg d.w. (p/b = 0.53). In the rat tumor sodium and potassium concentrations were 279 meq/kg d.w. (p/b = 0.44) and 510 meq/kg d.w. (p/b = 1.94). Non-tumorous tissue contained 237 meq/kg d.w. (p/b = 0) and 517 meq/kg d.w. (p/b = 1.98). In addition X-ray microanalysis could show that chlorine behaves like sodium, whereas the concentration of phosphorus and sulphur remains nearly constant. X-ray microanalysis in this case proved to be useful in the localization and quantification of different elements. The main disadvantage, however, is the reduced sensitivity for light elements, e.g. sodium, which cannot be determined in normal brain.

Evaluation of vasogenic edema in experimental brain tumors by cathodoluminescence and fluorescence microscopy

Cathodoluminescence and fluorescence microscopy have been used to study vasogenic edema in experimentally induced brain tumors in rats. Both methods are suited for the demonstration of FITC- or TRITC-coupled antiserum, and thus allow the evaluation of serum protein extravasation. Cathodoluminescence is more time consuming and laborious than fluorescence microscopy, but it has distinct advantages: Contrast enhancement improves the differentiation between certain cell types, and the higher resolution of the scanning electron microscope allows the identification of subcellular regions which cannot be recognized by conventional fluorescence microscopy.

Fibrous dysplasia in the light of new diagnostic methods

Various screening tests provide a detailed representation of fibrous dysplasia: thermography, scintigraphy, computer tomography, scanning electron microscopy, X-ray microanalysis, microradiography and fluorescence microscopy. The stationary nature of clinical and X-ray findings contrasts with the intensive structural changes that occur. The above-mentioned methods are examined with regard to differential diagnosis.

[Recessus and ganglia (author's transl)]

Preparated, communicating Recessus - Bursa suprapatellaris, Recessus popliteus and Bursa musculi gastrocnemii medialis - will be compared with ganglia. The surfaces document conformity. The REM-controls show a further proof of the gangliagenesis from recessus.

Comparison of the methods of cathodoluminescence, electronprobe microanalysis, and calcium staining, applied to human aorta with isthmus stenosis

Electron probe x-ray microanalysis is a useful method for studying pathologic and age-related calcification mechanisms in the aorta and in muscular arteries by means of elemental analysis in microareas. In the present investigation, this method was correlated with the histochemical alizarin-S-calcium staining and with cathodoluminescence analysis in the scanning electron microscope. Portions of the proximal region of a human aorta with isthmus stenosis was shock-frozen and sectioned in a cryostat. Serial sections were investigated by calcium staining, electron probe, and cathodoluminescence microanalysis. Using quantitative electron probe microanalysis of calcium and phosphorus, it was shown that the principal regions of calcium phosphate mineralization could be located using either alizarin-S staining or cathodoluminescence analysis. The advantage of the cathodoluminescence analysis is its higher lateral resolution compared with that of light microscopy, and the fact that no special staining is required. In addition, it was possible to obtain scanning images, thus providing additional information about the topology of the tissue surface, which is necessary to decide whether or not the section is suitable for microanalysis. Quantitative microanalysis is a valuable tool for basic research on calcified arteries. The results of the combined analysis in the proximal and distal regions as well as in the stenosis will be published in a later paper.

[Investigations on the contraceptive action of the Graefenberg ring. Historical review (author's transl)]

The biological activity of 2 Graefenberg rings was tested in vitro by electrone microscopy and X-ray microanalysis. The investigation showed that Graefenberg rings made of silver contain a varying amount of copper. The Graefenberg rings showed dissociation of copper in vitro which probably also occurred in the uterine cavity. The effect of the copper on the endometrium was probably a factor in the good contraceptive effectiveness of the Graefenberg silver ring compared for the silk thread intrauterine pessaries.

[Biological and medical applications of the cathodoluminescence in the scanning electron microscope (author's transl)]

The light emission according to the excitation of solids and molecules by electrons--named cathodoluminescence--extends the analytical field of applications of the scanning electron microscope. This method can be applied in biological and medical research. It can be used for the investigation of marked specimens similar to the fluorescence microscopy. The autoluminescence of some substances can also be used for special applications. The cathodoluminescence in the scanning electron microscope has the advantage that more sensitive detector-systems can be used than with the fluorescence microscope. Moreover, in the scanning microscope it is possible to combine the cathodoluminescence mode with other imaging or analytical equipments.

Glomerular microcapillary thrombosis demonstrated by the new technique of immunocathodoluminescence

Fluorescein-labeled antigen-antibody complexes could be made visible by scanning electron microscopy using an intensifying device. This new method of immunocathodoluminescence was demonstrated on cryostat sections of rat kidneys containing glomerular fibrin as the result of endotoxin infusion. The resulting photographs correspond with those obtained by immunofluorescent microscopy. The advantage of this technique is, however, the larger depth of focus. By using thinner cyostat sections it is expected that the higher resolution of scanning microscopy will provide even better details in three dimensions.