A colorimetric chemical tongue detects and distinguishes between multiple analytes.

The rate-limiting step for diagnostics development is the discovery and validation of biomarker analytes. We describe a new analyte-agnostic and label-free approach based on colorimetric reactions involving type I polymerization photoinitiators. We demonstrate that a chemically diverse array of hydrogels embedded with cleaved type I photoinitiators could act as microreactors, undergoing colorimetric reactions with bound analytes. The colorimetric signatures produced were visually distinctive and readable with a flatbed document scanner. Signatures of a broad range of sample types were accurately differentiated by unsupervised clustering without knowledge of any analytes bound to the array. The principles described have the potential to enable scalable and cost-effective analysis of complex samples.

Bilateral sacroiliitis following group C streptococcal sepsis.

Reactive arthritis particularly affects individuals 20 to 40 years old. The most common preceding infections are enteric and urogenital. The association of group C and group G streptococcal infections with reactive arthritis is rare. We present a case of old-onset bilateral sacroiliitis following group C streptococcal infection in an 81-year-old woman, treated successfully with a steroid taper and infliximab.

Unusual presentation of silently growing abdominal aortic aneurysm causing biliary obstruction.

Biliary obstruction is a rare presentation of abdominal aortic aneurysm (AAA). The most common symptoms of AAA are abdominal or back pain and limb ischaemia from thromboembolism. We report a case of a 67-year-old male who was diagnosed with obstructive jaundice secondary to an AAA. CT angiogram revealed compression of the common bile duct by the large AAA, causing diffuse intrahepatic and extrahepatic ductal dilatation. Surgical repair of the aortic aneurysm was successful, and patient's symptoms improved.

Protective Enterotoxigenic Escherichia coli Antigens in a Murine Intranasal Challenge Model.

Enterotoxigenic Escherichia coli (ETEC) is an endemic health threat in underdeveloped nations. Despite the significant effort extended to vaccine trials using ETEC colonization factors, these approaches have generally not been especially effective in mediating cross-protective immunity. We used quantitative proteomics to identify 24 proteins that differed in abundance in membrane protein preparations derived from wild-type vs. a type II secretion system mutant of ETEC. We expressed and purified a subset of these proteins and identified nine antigens that generated significant immune responses in mice. Sera from mice immunized with either the MltA-interacting protein MipA, the periplasmic chaperone seventeen kilodalton protein, Skp, or a long-chain fatty acid outer membrane transporter, ETEC_2479, reduced the adherence of multiple ETEC strains differing in colonization factor expression to human intestinal epithelial cells. In intranasal challenge assays of mice, immunization with ETEC_2479 protected 88% of mice from an otherwise lethal challenge with ETEC H10407. Immunization with either Skp or MipA provided an intermediate degree of protection, 68 and 64%, respectively. Protection was significantly correlated with the induction of a secretory immunoglobulin A response. This study has identified several proteins that are conserved among heterologous ETEC strains and may thus potentially improve cross-protective efficacy if incorporated into future vaccine designs.

Cross-Reactivity against Naja sumatrana (Black Spitting Cobra) Envenoming from the Haffkine Antivenom in a Mouse Model.

Naja sumatrana is the dominant cobra species in Malaysia, Singapore, Borneo, and Sumatra, and it does not have specific antivenom. The Haffkine antivenom has been advocated instead. This study aims to determine the efficacy of this antivenom against Naja sumatrana envenoming using a mouse model. Methods. Male Swiss albino mice were used. Intravenous LD50 was first determined separately for Naja naja and Naja sumatrana venom. ED50 was determined by preincubating antivenom with each venom at 2.5 LD50 before administering the mixture into the tail vein. Validation was carried out using a challenge test. Each mouse received 111 µg of Naja sumatrana venom intramuscularly followed by intraperitoneal administration of dilute Haffkine antivenom. Survival was recorded 24 hours after envenoming. Results. The LD50 of Naja naja venom was 78.13 µg, standard error (SE) 13.3 µg. The ED50 of the Haffkine antivenom against Naja naja venom was 45.9 mg, SE 7.5 mg. The LD50 and ED50 of Naja sumatrana venom were 55.5 µg, SE 12.0 µg; and 73.9 mg, SE 12.0 mg, respectively. The intra-peritoneal ED50 against 111 µg intramuscular Naja sumatrana venom was 136.95 mg, SE 36.74 mg. Conclusion. The Haffkine polyvalent antivenom exhibited cross-neutralisation against Naja sumatrana venom when used at a higher dose.

AUF1 is expressed in the developing brain, binds to AT-rich double-stranded DNA, and regulates enkephalin gene expression.

During our search for transcriptional regulators that control the developmentally regulated expression of the enkephalin (ENK) gene, we identified AUF1. ENK, a peptide neurotransmitter, displays precise cell-specific expression in the adult brain. AUF1 (also known as heterogeneous nuclear ribonucleoprotein D) has been known to regulate gene expression through altering the stability of AU-rich mRNAs. We show here that in the developing brain AUF1 proteins are expressed in a spatiotemporally defined manner, and p37 and p40/42 isoforms bind to an AT-rich double-stranded (ds) DNA element of the rat ENK (rENK) gene. This AT-rich dsDNA sequence acts as a cis-regulatory DNA element and is involved in regulating the cell-specific expression of the ENK gene in primary neuronal cultures. The AT-rich dsDNA elements are present at approximately 2.5 kb 5'upstream of the rat, human, and mouse ENK genes. AUF1 proteins are shown here to provide direct interaction between these upstream AT-rich DNA sequences and the TATA region of the rENK gene. Double immunohistochemistry demonstrated that in the developing brain AUF1 proteins are expressed by proliferating neural progenitors and by differentiating neurons populating brain regions, which will not express the ENK gene in the adult, suggesting a repressor role for AUF1 proteins during enkephalinergic differentiation. Their subnuclear distribution and interactions with AT-rich DNA suggest that in the developing brain they can be involved in complex nuclear regulatory mechanisms controlling the development- and cell-specific expression of the ENK gene.

Effects of topical heparin, antivenom, tetracycline and dexamethasone treatment in corneal injury resulting from the venom of the black spitting cobra (Naja sumatrana), in a rabbit model.

BACKGROUND: The Naja sumatrana cobra can spit venom in defense and may result in permanent blindness. The study sought to determine the efficacy of topical heparin, Haffkine antivenom, tetracycline and dexamethasone. MATERIALS AND METHODS: Male New Zealand White Rabbits were used. Pooled venom was frozen at -30 degrees C. 0.05 mL of 20 times dilute venom was introduced into the conjunctiva, in groups of three rabbits randomly. Heparin at 5000 IU/mL, Haffkine antivenom or saline control was administered repeatedly on each rabbit's eye over 158 minutes, after a specified delay. In other groups, 1% tetracycline, 0.1% dexamethasone or a placebo ointment was applied and repeated at 24 and 48 hours. All the rabbits were assessed after 24, 48, 72 hours, one and two weeks by an ophthalmologist blinded to the treatment arms. OBSERVATIONS: Following ocular envenomation, there was immediate blepharospasm, lacrimal secretions, redness and chemosis; more intense in the normal saline group. The Roper-Hall grades improved, corneas re-epithelialized and inflammation quietened in the heparin and antivenom-treated rabbit eyes compared to controls. Scarring appeared from the first week, but ameliorated in the heparin and antivenom groups. Heparin treatment remained efficacious up to four minutes delay. The tetracycline, dexamethasone and placebo groups had worsening Roper-Hall trends, greater corneal epithelial loss, inflammation and scarring. Combined heparin-tetracycline therapy was as efficacious with heparin alone. CONCLUSION: Topical heparin or antivenom therapy significantly improved overall outcomes in rabbit corneas exposed to Naja sumatrana venom, compared to tetracycline, dexamethasone and controls. Heparin treatment remains efficacious up to 4 minutes delay.

RNA recognition site of PP7 coat protein.

The coat proteins of different single-strand RNA phages use a common protein tertiary structural framework to recognize different RNA hairpins and thus offer a natural model for understanding the molecular basis of RNA-binding specificity. Here we describe the RNA structural requirements for binding to the coat protein of bacteriophage PP7, an RNA phage of Pseudomonas. Its recognition specificity differs substantially from those of the coat proteins of its previously characterized relatives such as the coliphages MS2 and Qbeta. Using designed variants of the wild-type RNA, and selection of binding-competent sequences from random RNA sequence libraries (i.e. SELEX) we find that tight binding to PP7 coat protein is favored by the existence of an 8 bp hairpin with a bulged purine on its 5' side separated by 4 bp from a 6 nt loop having the sequence Pu-U-A-G/U-G-Pu. However, another structural class possessing only some of these features is capable of binding almost as tightly.

Recognition of diverse RNAs by a single protein structural framework.

The coat proteins of different single-strand RNA phages utilize a common structural framework to recognize different RNA targets, making them suitable models for studies of RNA-protein recognition generally, especially for the class of proteins that bind RNA on a beta-sheet surface. Here we show that structurally distinct molecules are capable of satisfying the requirements for binding to Qbeta coat protein. Although the predicted secondary structures of the RNAs differ markedly, we contend that they are approximately equivalent structurally in their complexes with coat protein. Based on our prior observations that the RNA-binding specificities of Qbeta and MS2 coat proteins can be interconverted with as few as one amino acid substitution each, and taking into account details of the structures of complexes of MS2 coat protein with wild-type and aptamer RNAs, we propose a model for the Qbeta coat protein-RNA complex.