Detection of biological toxins on an active electronic microchip

An electric-field-driven assay for fluorescein-labeled staphylococcal enterotoxin B and cholera toxin B was developed on an active electronic microchip. An array of microlocations was transformed into an immunoassay array by electronically biasing electrodes at each microlocation to attract biotinylated capture antibodies. The electric field generated on the array directed the transport, concentration, and binding of biotinylated capture antibodies to streptavidin-coated microlocations. Subsequently, solutions of fluorescein-labeled staphylococcal enterotoxin B and fluorescein-labeled cholera toxin B were electronically addressed to the assay sites by an applied electric field. Each toxin was specifically bound to microlocations containing the appropriate capture antibody with little nonspecific binding to assay sites lacking the appropriate capture antibody. It was possible to detect both toxins from a mixture in a single electronic addressing step; detection was accomplished after a 1-min application of the electric field followed by washing. The ability to perform a rapid, electric field-mediated immunoassay for multiple analytes may provide an advantage over existing approaches.     

Structure–activity relationships in platinum–acridinylthiourea conjugates: effect of the thiourea nonleaving group on drug stability, nucleobase affinity, and in vitro cytotoxicity

The synthesis, cytotoxicity, and nucleoside binding of some platinum–acridinylthiourea conjugates derived from the prototypical compound [PtCl(en)(ACRAMTU)](NO₃)₂ {PT-ACRAMTU; en=ethane-1,2-diamine, ACRAMTU=1-[2-(acridin-9-ylamino)ethyl]-1,3-dimethylthiourea, protonated form} are reported. To establish structure–activity relationships within this class of compounds, systematic changes were made to the thiourea nonleaving group, which links the intercalator to platinum. Three new derivatives of ACRAMTU, one di-, one tri-, and one tetraalkylated, were generated, where the degree of alkylation indicates the number of alkyl groups attached to the SCN₂ framework. Subsequent reaction of the tri- and tetraalkylated derivatives with activated [PtCl₂(en)] yielded the corresponding platinum conjugates. The dialkylated thiourea gave an unstable complex, which was not included in the studies. The crystal structure of PT-ACRAMTU·MeOH has been determined. In the solid state, one axial position of the square-planar platinum coordination sphere is partially shielded by the bulky thiourea group, providing a strong rationale for the kinetic inertness of the compound. The cytotoxicity of the prototype, the two new conjugates, and cisplatin was assessed in ovarian (A2780, A2780/CP), lung (NCI-H460), and colon (RKO) cancer cell lines using clonogenic survival assays. The derivatives containing trialkylated thiourea groups showed activity similar or superior to cisplatin, with IC₅₀ values in the low micromolar concentration range. The complex modified with the tetraalkylated (bulkiest) thiourea was significantly less active, possibly due to the greatly decreased rate of binding to nucleobase nitrogen (¹H NMR spectroscopy), but was most efficient at overcoming cross resistance to cisplatin in A2780/CP. Possible consequences of the reported structural modifications for the mechanism of action of these agents are discussed.Electronic Supplementary Material Supplementary material is available in the online version of this article at Abbreviations ACRAMTU 1-[2-(acridin-9-ylamino)ethyl]-1,3-dimethylthiourea - Boc t-butyl carbamate - dGuo 2-deoxyguanosine - dien N¹-(2-aminoethyl)ethane-1,2-diamine - en ethane-1,2-diamine - HEPES 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid - PT-ACRAMTU [PtCl(en)(ACRAMTU)](NO₃)₂ - TSP 3-(trimethylsilyl)propionate, sodium salt     

Papilin in development; a pericellular protein with a homology to the ADAMTS metalloproteinases

Papilin is an extracellular matrix glycoprotein that we have found to be involved in, (1) thin matrix layers during gastrulation, (2) matrix associated with wandering, phagocytic hemocytes, (3) basement membranes and (4) space-filling matrix during Drosophila development. Determination of its cDNA sequence led to the identification of Caenorhabditis and mammalian papilins. A distinctly conserved 'papilin cassette' of domains at the amino-end of papilins is also the carboxyl-end of the ADAMTS subgroup of secreted, matrix-associated metalloproteinases; this cassette contains one thrombospondin type 1 (TSR) domain, a specific cysteine-rich domain and several partial TSR domains. In vitro, papilin non-competitively inhibits procollagen N-proteinase, an ADAMTS metalloproteinase. Inhibiting papilin synthesis in Drosophila or Caenorhabditis causes defective cell arrangements and embryonic death. Ectopic expression of papilin in Drosophila causes lethal abnormalities in muscle, Malpighian tubule and trachea formation. We suggest that papilin influences cell rearrangements and may modulate metalloproteinases during organogenesis.     

Deletion 17q12 is a recurrent copy number variant that confers high risk of autism and schizophrenia

Autism spectrum disorders (ASD) and schizophrenia are neurodevelopmental disorders for which recent evidence indicates an important etiologic role for rare copy number variants (CNVs) and suggests common genetic mechanisms. We performed cytogenomic array analysis in a discovery sample of patients with neurodevelopmental disorders referred for clinical testing. We detected a recurrent 1.4 Mb deletion at 17q12, which harbors HNF1B, the gene responsible for renal cysts and diabetes syndrome (RCAD), in 18/15,749 patients, including several with ASD, but 0/4,519 controls. We identified additional shared phenotypic features among nine patients available for clinical assessment, including macrocephaly, characteristic facial features, renal anomalies, and neurocognitive impairments. In a large follow-up sample, the same deletion was identified in 2/1,182 ASD/neurocognitive impairment and in 4/6,340 schizophrenia patients, but in 0/47,929 controls (corrected p = 7.37 × 10⁻⁵). These data demonstrate that deletion 17q12 is a recurrent, pathogenic CNV that confers a very high risk for ASD and schizophrenia and show that one or more of the 15 genes in the deleted interval is dosage sensitive and essential for normal brain development and function. In addition, the phenotypic features of patients with this CNV are consistent with a contiguous gene syndrome that extends beyond RCAD, which is caused by HNF1B mutations only.     

Reduced transforming growth factor-beta signaling in cartilage of old mice: role in impaired repair capacity

Osteoarthritis (OA) is a common joint disease, mainly effecting the elderly population. The cause of OA seems to be an imbalance in catabolic and anabolic factors that develops with age. IL-1 is a catabolic factor known to induce cartilage damage, and transforming growth factor (TGF)-beta is an anabolic factor that can counteract many IL-1-induced effects. In old mice, we observed reduced responsiveness to TGF-beta-induced IL-1 counteraction. We investigated whether expression of TGF-beta and its signaling molecules altered with age. To mimic the TGF-beta deprived conditions in aged mice, we assessed the functional consequence of TGF-beta blocking. We isolated knee joints of mice aged 5 months or 2 years, half of which were exposed to IL-1 by intra-articular injection 24 h prior to knee joint isolation. Immunohistochemistry was performed, staining for TGF-beta1, -2 or -3, TGF-betaRI or -RII, Smad2, -3, -4, -6 and -7 and Smad-2P. The percentage of cells staining positive was determined in tibial cartilage. To mimic the lack of TGF-beta signaling in old mice, young mice were injected with IL-1 and after 2 days Ad-LAP (TGF-beta inhibitor) or a control virus were injected. Proteoglycan (PG) synthesis (³⁵S-sulfate incorporation) and PG content of the cartilage were determined. Our experiments revealed that TGF-beta2 and -3 expression decreased with age, as did the TGF-beta receptors. Although the number of cells positive for the Smad proteins was not altered, the number of cells expressing Smad2P strongly dropped in old mice. IL-1 did not alter the expression patterns. We mimicked the lack of TGF-beta signaling in old mice by TGF-beta inhibition with LAP. This resulted in a reduced level of PG synthesis and aggravation of PG depletion. The limited response of old mice to TGF-beta induced-IL-1 counteraction is not due to a diminished level of intracellular signaling molecules or an upregulation of intracellular inhibitors, but is likely due to an intrinsic absence of sufficient TGF-beta receptor expression. Blocking TGF-beta distorted the natural repair response after IL-1 injection. In conclusion, TGF-beta appears to play an important role in repair of cartilage and a lack of TGF-beta responsiveness in old mice might be at the root of OA development.     

Feline leukemia virus infection as a potentiating cofactor for the primary and secondary stages of experimentally induced feline immunodeficiency virus infection.

Preexistent feline leukemia virus (FeLV) infection greatly potentiated the severity of the transient primary and chronic secondary stages of feline immunodeficiency virus (FIV) infection. Of 10 FeLV-FIV carrier cats, 5 died of experimentally induced FIV infection, compared with 2 deaths in 10 cats infected only with FeLV and 1 death in 7 cats infected only with FIV. FIV-infected cats with preexistent FeLV infections developed severe depression, anorexia, fever, diarrhea, dehydration, weight loss, and leukopenia 4 to 6 weeks after infection and were moribund within 2 weeks of the onset of signs, whereas cats infected only with FIV developed much milder self-limiting gross and hematologic abnormalities. Pathologic findings in dually infected cats that died were similar to those observed previously in cats dying from uncomplicated primary FIV infection but were much more widespread and severe. Coinfection of asymptomatic FeLV carrier cats with FIV did not increase the levels of FeLV p27 antigen present in their blood over that seen in cats infected with FeLV alone. The amount of proviral FIV DNA was much higher, however, in dually infected cats than in cats infected only with FIV; there was a greater expression of FIV DNA in lymphoid tissues, where the genome was normally detected, and in nonlymphoid tissues, where FIV DNA was not usually found. Dually infedted cats that recovered from the primary stage of FIV infection remained more leukopenic than cats infected with FIV or FeLV alone, and their CD4+/CD8+ T-lymphocyte ratios were inverted. One of these cats developed what was considered to be an opportunistic infection. It was concluded, therefore, that a preexistent FeLV infection in some way enhanced the expression and spread of FIV in the body and increased the severity of both the resulting transient primary and chronic secondary stages of FIV infection. This study also demonstrated the usefulness of the FIV model in studying the role of incidental infectious diseases as cofactors for immunodeficiency-causing lentiviruses.