Huntington's disease is a progressive neurodegenerative disorder caused by a polyglutamine [poly(Q)] repeat expansion in the first exon of the huntingtin protein.Previously, we showed that N-terminal huntingtin peptides with poly(Q) tracts in the pathological range (51-122 glutamines), but not with poly(Q) tracts in the normal range (20 and 30 glutamines), form high molecular weight protein aggregates with a fibrillar or ribbon-like morphology, reminiscent of scrapie prion rods and ␤-amyloid fibrils in Alzheimer's disease. Here we report that the formation of amyloidlike huntingtin aggregates in vitro not only depends on poly(Q) repeat length but also critically depends on protein concentration and time. Furthermore, the in vitro aggregation of huntingtin can be seeded by preformed fibrils. Together, these results suggest that amyloid fibrillogenesis in Huntington's disease, like in Alzheimer's disease, is a nucleation-dependent polymerization.

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The accumulation of insoluble protein aggregates in intra and perinuclear inclusions is a hallmark of Huntington's disease (HD) and related glutamine-repeat disorders. A central question is whether protein aggregation plays a direct role in the pathogenesis of these neurodegenerative diseases. Here we show by using a filter retardation assay that the mAb 1C2, which specifically recognizes the elongated polyglutamine (polyQ) stretch in huntingtin, and the chemical compounds Congo red, thioflavine S, chrysamine G, and Direct fast yellow inhibit HD exon 1 protein aggregation in a dose-dependent manner. On the other hand, potential inhibitors of amyloid-␤ formation such as thioflavine T, gossypol, melatonin, and rifampicin had little or no inhibitory effect on huntingtin aggregation in vitro. The results obtained by the filtration assay were confirmed by electron microscopy, SDS͞ PAGE, and MS. Furthermore, cell culture studies revealed that the Congo red dye at micromolar concentrations reduced the extent of HD exon 1 aggregation in transiently transfected COS cells. Together, these findings contribute to a better understanding of the mechanism of huntingtin fibrillogenesis in vitro and provide the basis for the development of new huntingtin aggregation inhibitors that may be effective in treating HD.glutamine repeat ͉ inhibition

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 Ϸ184,000 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-dimethylbenzothiazol-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.

A nonfluorescent low-cost, low-density oligonucleotide array was designed for detecting the whole coronavirus genus after reverse transcription (RT)-PCR. The limit of detection was 15.7 copies/reaction. The clinical detection limit in patients with severe acute respiratory syndrome was 100 copies/sample. In 39 children suffering from coronavirus 229E, NL63, OC43, or HKU1, the sensitivity was equal to that of individual real-time RT-PCRs.Coronaviruses (CoV) (family Coronaviridae, order Nidovirales) are large enveloped RNA viruses with a 27-to 32-kb genome of positive polarity. They comprise a very diverse spectrum of pathogens of humans and animals (2, 7). The coronavirus etiology of severe acute respiratory syndrome (SARS) and the recent discoveries of the novel human coronaviruses (hCoV) NL63 and HKU1 (5, 13, 15) have triggered intensified efforts in virus identification and diagnostics. Generic reverse transcription (RT)-PCR assays with a very broad detection range are required, but few such assays are available. None of them has been previously validated in a diagnostic setting (9, 12).The requirement for sequencing in order to achieve strain identification limits the applicability of generic PCR assays in general. Alternative techniques, such as mass spectrometry or complex fluorescent DNA microarrays, have been proposed (10), but these will often be too sophisticated for medical facilities. We describe here a simple and feasible approach to detecting the full spectrum of coronaviruses with diagnostic sensitivity, combining generic RT-PCR and low-cost, low-density (LCD) DNA microarrays which can be read with the naked eye.Primers for universal RT-PCR for the genus Coronavirus were designed after aligning all coronavirus RNA-dependent RNA polymerase genes. RNA-dependent RNA polymerase motifs A and C were targeted because they contain short amino acid patterns that are 100% identical in all coronaviruses (16). Primer binding regions corresponded to patterns LMGWDYPKCD and MMILSDDAV, comprising domains essential for metal ion chelation and binding of the primer 3Ј-end/template complex (11, 16). Reactions (25-l mixtures) were carried out using the QIAGEN (Hilden, Germany) one-step RT-PCR kit, with 200 nM of primer PC2S2 (equimolar mixture of TTATGGGTTGGGAT TATC and TGATGGGATGGGACTATC), 900 nM of primer PC2As1 (equimolar mixture of TCATCACTCAGAATCATCA, TCATCAGAAAGAATCATCA, and TCGTCGGACAAGATC ATCA), 1 l QIAGEN one-step RT-PCR kit enzyme mix, and 5 l RNA extract. The amplification procedure comprised 30 min at 50°C; 15 min at 95°C; 10 cycles of 20 s at 94°C, 30 s starting at 62°C with a decrease of 1°C per cycle, and 40 s at 72°C; and 30 cycles of 20 s at 95°C, 30 s at 52°C, and 40 s at 72°C. To determine the sensitivity of the assay, the target regions including sufficient stretches of flanking sequence were cloned from several coronaviruses (Table 1) and transcribed into RNA (3, 4). Amplification

KRAS mutation testing before anti-epidermal growth factor receptor therapy of metastatic colorectal cancer has become mandatory in Europe. However, considerable uncertainty exists as to which methods for detection can be applied in a reproducible and economically sound manner in the routine diagnostic setting. To answer this question, we examined 263 consecutive routine paraffin slide specimens. Genomic DNA was extracted from microdissected tumor tissue. The DNA was analyzed prospectively by Sanger sequencing and array analysis as well as retrospectively by melting curve analysis and pyrosequencing; the results were correlated to tissue characteristics. The methods were then compared regarding the reported results, costs, and working times. Approximately 40% of specimens contained KRAS mutations, and the different methods reported concordant results (kappa values >0.9). Specimens harboring fewer than 10% tumor cells showed lower mutation rates regardless of the method used, and histoanatomical variables had no influence on the frequency of the mutations. Costs per assay were higher for array analysis and melting curve analysis when compared with the direct sequencing methods. However, for sequencing methods equipment costs were much higher. In conclusion, Sanger sequencing, array analysis, melting curve analysis, and pyrosequencing were equally effective for routine diagnostic KRAS mutation analysis; however, interpretation of mutation results in conjunction with histomorphologic tissue review and on slide tumor tissue dissection is required for accurate diagnosis.

Respiratory complex I of plant mitochondria has to date been investigated with respect to physiological function, biochemical properties and molecular structure. In the respiratory chain complex I is the major entry gate for low potential electrons from matrix NADH, reducing ubiquinone and utilizing the released energy to pump protons across the inner membrane. Plant complex I is active against a background of several other NAD(P)H dehydrogenases, which do not contribute in proton pumping, but permit and establish several different routes of shuttling electrons from NAD(P)H to ubiquinone. Identification of the corresponding molecular structures, that is the proteins and genes of the different NADH dehydrogenases, will allow more detailed studies of this interactive regulatory network in plant mitochondria. Present knowledge of the structure of complex I and the respective mitochondrial and nuclear genes encoding various subunits of this complex in plants is summarized here. Copyright 1998 Elsevier Science B.V.

The LCD array protocol takes 45 min (15 min 'hands-on' time) after prior PCR amplification. Only minimal laboratory equipment is required. LCD arrays provide a rapid and economical method to characterize mutations in codon 315 of the katG gene, in the mabA-inhA regulatory region and in the rpoB gene.