Chemoselective umpolung of thiols to episulfoniums for cysteine bioconjugation.

Cysteine conjugation is an important tool in protein research and relies on fast, mild and chemoselective reactions. Cysteinyl thiols can either be modified with prefunctionalized electrophiles, or converted into electrophiles themselves for functionalization with selected nucleophiles in an independent step. Here we report a bioconjugation strategy that uses a vinyl thianthrenium salt to transform cysteine into a highly reactive electrophilic episulfonium intermediate in situ, to enable conjugation with a diverse set of bioorthogonal nucleophiles in a single step. The reactivity profile can connect several nucleophiles to biomolecules through a short and stable ethylene linker, ideal for introduction of infrared labels, post-translational modifications or NMR probes. In the absence of reactive exogenous nucleophiles, nucleophilic amino acids can react with the episulfonium intermediate for native peptide stapling and protein-protein ligation. Ready synthetic access to isotopologues of vinyl thianthrenium salts enables applications in quantitative proteomics. Such diverse applications demonstrate the utility of vinyl-thianthrenium-based bioconjugation as a fast, selective and broadly applicable tool for chemical biology.

Sex identification in juvenile and adult Indonesian blue-tongued skinks (Tiliqua gigas) through cystoscopy and accuracy of contrast radiography.

OBJECTIVE: To describe a nonsurgical endoscopic technique for sex identification in Indonesian blue-tongued skinks (Tiliqua gigas) and to assess accuracy of contrast radiography of the hemipenile/hemiclitoral pouches. ANIMALS: 42 clinically healthy Indonesian blue-tongued skinks between 6 months and 3 years old and weighing between 22 and 550 g. METHODS: Cystoscopy was performed under general anesthesia. Gonads were visualized through the transparency of the urinary bladder, and their gross morphology was described. Contrast was applied in the tail pouches before obtaining full-body radiographs. Two radiologists, blinded to the sex of the skink, evaluated the radiographs. RESULTS: Cystoscopy was achieved in all 42 skinks. Visualization of the gonads through the urinary bladder was possible in 41 (98%; 95% CI, 87% to 99%) of the skinks, with 18 of them identified as males and 23 identified as females. Median procedure time was 60 seconds (range, 25 to 180 seconds) and was not associated with procedure order (-0.69; 95% CI, -1.83 to 0.45) or with the weight (0.02 g; 95% CI, -0.07 to 1.0) or the identified sex (11.7; 95% CI, -15.07 to 38.45) of the skink. Radiographs had a sensitivity of 69.6% (95% CI, 47.1% to 86.8%) and a specificity of 75.0% (47.6% to 92.7%) to identify female skinks. All the skinks recovered uneventfully. CLINICAL RELEVANCE: Cystoscopic sex identification is feasible in Indonesian blue-tongued skinks of various age and size. Considering the difficulty in identifying their sex otherwise, this technique could provide a significant improvement in the veterinary care of this species. In this population, contrast radiographs showed limited accuracy for sex identification.

Concomitant Congenital Diaphagmatic Hernia (CDH) and bilateral bacterial glomerulonephritis in a pet chinchilla (Chinchilla lanigera).

BACKGROUND: The domestic chinchilla has been descended from Chinchilla lanigera (long-tailed Chinchilla) or Chinchilla chinchilla (short-tailed Chinchilla). Both species of chinchilla are currently listed as endangered by the IUCN Red List of Threatened Species. Over the past 20 years, they have spread as pets and overall knowledge about their care is improving. The present case report describes a congenital diaphragmatic hernia in a Chinchilla lanigera. CASE PRESENTATION: A 1-year-old, 420 g female chinchilla (Chinchilla lanigera) was presented for clinical examination due to 2 days haematuria episodes and anorexia. A complete haematological analysis was performed, showing a moderate neutrophilia and severe renal involvement. X-rays showed severe intestinal meteorism affecting mostly the cecum, and a soft tissue density mass with translucent areas located in the caudal thorax, making it hard to distinguish the cardiac silhouette. A barium swallow (barium sulfate) was performed and after 20 min, radiograms were performed again, showing part of the stomach dislocated in thorax. Ultrasound was also carried out, confirming the partial stomach herniation into the thoracic cavity and a severe nephropathy. The patient was euthanized according to the owner's wish and a complete necropsy was performed. The diagnosis was congenital diaphragmatic hernia concomitant to a severe bilateral bacterial glomerulonephritis. DISCUSSION AND CONCLUSIONS: Diaphragmatic hernias can be either congenital or acquired. About CDHs in pet chinchillas, literature is still lacking. In this patient there was no history of previous traumas. No scar tissue or thickening involved margins of the pathological diaphragm window at the necropsy, supporting the hypothesis of a congenital defect. Glomerulonephritis most often results from immune-mediated mechanisms, generally after the deposition of soluble immune complexes within the glomeruli. This mechanism is favoured by a prolonged antigenemia that could occur during specific viral infections, chronic bacterial infections, chronic parasitism, autoimmune diseases and neoplasia. Few cases of nephritis are described in chinchillas (Chinchilla lanigera), mostly related to bacterial sepsis or less commonly involving fungi. The evidence of bacterial aggregates in kidneys at the histopathology, confirmed the infective aetiology. No relationship between the diaphragmatic hernia and glomerulonephritis was found in this report.

Acute tea tree oil intoxication in a pet cockatiel (Nymphicus hollandicus): a case report.

BACKGROUND: Phytotherapy is becoming a more and more common practice, not only for personal care but also for pet care. Nevertheless, we often have to deal with substances on which, in most cases, very little literature is available, even more so if the species of interest are the exotic ones. In particular, the essential oil from the Melaleuca leaves, because of its antinflammatory and antibacterial properties, is widely used and very little is known about its potential toxicity on pet birds. The present paper describes the first case of Tea tree oil intoxication in a pet bird. CASE PRESENTATION: A one-year-old, 80 g male cockatiel (Nymphicus hollandicus) was presented for clinical examination due to a serious despondency episode after the application of 3 drops of tea tree oil (Melaleuca alternifoglia) directly on the cutis of its right wing. The subject was urgently hospitalized and blood tests were performed.Serum biochemical values showed severe liver damage and slight renal involvement, complete blood count (CBC) parameters indicated a moderate neutrophilia a moderate neutropenia. Warm subcutaneous fluids and vitamin (VIT) B12 were administered, and after 8 h of fluid therapy the clinical condition of the patient improved. The subject was discharged after 48 h of hospitalization, in stable conditions. CONCLUSIONS: Toxicosis are relatively common in bird pets and a number of cases are reported in literature, concerning heavy metals intoxications and toxic plants ingestion. However, in literature there are no described cases regarding Melaleuca oil intoxication in pet birds, but it has been reported in humans (mainly by ingestion) as well as in dogs, cats and rats. We hope that this first case report can be an initial aid in the knowledge of this potential toxicosis and therefore in the clinical veterinary practice of pet birds.

Studying the fragmentation mechanism of selected components present in crude oil by collision-induced dissociation mass spectrometry.

RATIONALE: Structural characterization of individual compounds in very complex mixtures is difficult to achieve. One important step in structural elucidation is understanding the mass spectrometric fragmentation mechanisms of the compounds present in such mixtures. Here, different individual compounds presumed to be present in a complex crude oil mixture have been synthesized and structurally characterized by tandem mass spectrometry (MS/MS) studies. METHODS: Model compounds with different aromatic cores and various substitutents were synthesized. Major effort has been put into producing isomerically pure compounds to better understand the fragmentation pattern. Each synthesized compound has been subjected to MSn studies using either a triple quadrupole or a linear ion trap mass spectrometer with electrospray or atmospheric pressure photoionization. The results are used to analyze individual compounds from a complex vacuum gas oil (VGO). RESULTS: The synthesized compounds and a chromatographically simplified vacuum gas oil were used for structural analysis. The major fragmentation mechanism is the benzylic cleavage of the aliphatic side chain. Each side chain can be separately removed from the aromatic core by using MSn methods. At the end of a series of fragmentations, the base aromatic core structure remains and can be chararcterized. CONCLUSIONS: By defining the fragmentation mechanism in complex oil samples it was possible to structurally characterize individual compounds present in a chromatographically simplified VGO. The compounds consist of an aromatic core with aliphatic side chains. Cleavage of all side chains can be achieved by MSn measurements, allowing characterization of the remaining core structure.

Quantitative and Qualitative Analysis of Three Classes of Sulfur Compounds in Crude Oil.

Owing to the environmental hazards arising from sulfur-containing combustion products, strong legal regulations exist to reduce the sulfur content of transportation fuels down to a few ppm. With the ongoing depletion of low-sulfur crude oil reservoirs, increased technological efforts are needed for crude oil refining to meet these requirements. The desulfurization step is a critical part of the refining process but partly suffers from the recalcitrance of certain species to sulfur removal and the inability to quantitatively understand the behavior of individual compound classes during the process. We herein present a new and simple approach for the parallel quantification of three different classes of sulfur species present in crude oils by LC separation and on-line detection and quantification by ICP-MS/MS. This approach will help to estimate the amount of recalcitrant species and thus facilitate the optimization of desulfurization conditions during fuel production.