Host-Guest Induced Peptide Folding with Sequence-Specific Structural Chirality.

Controlling the spatial and temporal behavior of peptide segments is essential in the fabrication of functional peptide-based materials and nanostructures. To achieve a desired structure, complex sequence design is often required, coupled with the inclusion of unnatural amino acids or synthetic modifications. Herein, we investigate the structural properties of 1:1 inclusion complexes between specific oligopeptides and cucurbit[8]uril (CB[8]), inducing the formation of turns, and by alteration of the peptide sequence, tunable structural chirality. We also explore extended peptide sequence binding with CB[8], demonstrating a simple approach to construct a peptide hairpin.

Oligopeptide-CB[8] complexation with switchable binding pathways.

Host-guest complexes exhibiting a 1 : 1 binding stoichiometry need not consist of a single host and guest. A series of oligopeptides, which were previously reported to have abnormally high binding enthalpies were investigated to deduce whether they exist as a 2 : 2 quaternary or a 1 : 1 binary complex with cucurbit[8]uril (CB[8]). Through a systematic study of the sequence-specific binding pathways of peptide-CB[8] association, a phenylalanine-leucine dipeptide was found to be capable of switching from a 1 : 1 stoichiometric complex to a 2 : 1 complex. By studying the differences in size-based diffusion properties of these two binding modes, the presence of a 1 : 1 pairwise inclusion complex was verified for the regime where CB[8] is in excess. Findings in this study can be utilised to 'customise' the precise CB[8]-oligopeptide self-assembly pathway, acting as a useful toolbox in the design of supramolecular systems.

Tunable Pentapeptide Self-Assembled ß-Sheet Hydrogels.

Oligopeptide-based supramolecular hydrogels hold promise in a range of applications. The gelation of these systems is hard to control, with minor alterations in the peptide sequence significantly influencing the self-assembly process. We explored three pentapeptide sequences with different charge distributions and discovered that they formed robust, pH-responsive hydrogels. By altering the concentration and charge distribution of the peptide sequence, the stiffness of the hydrogels could be tuned across two orders of magnitude (2-200 kPa). Also, through reassembly of the ß-sheet interactions the hydrogels could self-heal and they demonstrated shear-thin behavior. Using spectroscopic and cryo-imaging techniques, we investigated the relationship between peptide sequence and molecular structure, and how these influence the mechanical properties of the hydrogel. These pentapeptide hydrogels with tunable morphology and mechanical properties have promise in tissue engineering, injectable delivery vectors, and 3D printing applications.

Self-Healing, Self-Assembled ß-Sheet Peptide-Poly(γ-glutamic acid) Hybrid Hydrogels.

Self-assembled biomaterials are an important class of materials that can be injected and formed in situ. However, they often are not able to meet the mechanical properties necessary for many biological applications, losing mechanical properties at low strains. We synthesized hybrid hydrogels consisting of a poly(γ-glutamic acid) polymer network physically cross-linked via grafted self-assembling ß-sheet peptides to provide non-covalent cross-linking through ß-sheet assembly, reinforced with a polymer backbone to improve strain stability. By altering the ß-sheet peptide graft density and concentration, we can tailor the mechanical properties of the hydrogels over an order of magnitude range of 10-200 kPa, which is in the region of many soft tissues. Also, due to the ability of the non-covalent ß-sheet cross-links to reassemble, the hydrogels can self-heal after being strained to failure, in most cases recovering all of their original storage moduli. Using a combination of spectroscopic techniques, we were able to probe the secondary structure of the materials and verify the presence of ß-sheets within the hybrid hydrogels. Since the polymer backbone requires less than a 15% functionalization of its repeating units with ß-sheet peptides to form a hydrogel, it can easily be modified further to incorporate specific biological epitopes. This self-healing polymer-ß-sheet peptide hybrid hydrogel with tailorable mechanical properties is a promising platform for future tissue-engineering scaffolds and biomedical applications.

Day one core competencies in veterinary dentistry.

This article describes the core competencies recommended for inclusion in the veterinary curriculum for all veterinary graduates based on the American Association of Veterinary Medical Colleges Competency-Based Veterinary Education document. General practice companion animal veterinarians are frequently presented with patients having dental, oral, or maxillofacial pathology, and veterinary graduates will be relied upon for recommendations for the maintenance of oral health, including the prevention of periodontal disease, identification of endodontic disease, and knowledge of developmental defects. These recommendations should be made for all veterinary patients starting at a young age. These core competencies can apply to many companion species, but mainly are focused on the dog and cat. Because periodontal disease is the most common abnormality observed in dogs and cats, the first key step is taking a few seconds during examination of every patient of any age presented for any reason to examine the oral cavity. Although dental, oral, and maxillofacial pathology is often diagnosed after imaging and evaluation under anesthesia, the first step is observation of dentition and gingivae during the conscious exam to assess periodontal health status. The physical exam of the oral cavity may reveal oral behavior (eg, observation of uncomplicated crown fractures due to chewing on hard objects), which will permit recommendations for enhanced prevention by daily oral hygiene or professional treatment. There are now many involved dental and surgical treatments available, some of which require specialist-level instrumentation and expertise. General practitioners should be able to competently perform the following immediately upon graduation from veterinary school: For patients for whom the owner's reason for the veterinary visit is not dental, oral, or maxillofacial disease, obtain a brief (1 or 2 questions) history of the oral health of the patient. On lifting the lip of every patient, recognize presence or absence of accumulated dental plaque or calculus on the crowns of the teeth, presence or absence of gingival inflammation or ulceration, and presence or absence of other dental, oral, and maxillofacial pathology. On anesthetized patients that have dental, oral, and maxillofacial pathology for which professional treatment is indicated, be able to obtain and interpret appropriately positioned and exposed dental radiographs. When the presence of dental, oral, and maxillofacial pathology is recognized, determine whether each tooth present in the mouth does or does not require professional treatment beyond dental subgingival and supragingival scaling and polishing. List the indications for tooth extraction, know indications for potential oral/dental treatments beyond subgingival and supragingival scaling and polishing or extraction, and determine whether the professional treatment that may be indicated, such as root canal treatment or mass resection of oral tissues, requires referral for specialist-level expertise and instrumentation. Complete a thorough periodontal evaluation and therapy with periodontal probing, including professional subgingival and supragingival ultrasonic scaling with polishing under anesthesia. Demonstrate the ability to extract teeth indicated for extraction, using gentle and appropriate techniques that will risk minimal injury to the jaws and oral soft tissues and reduce postoperative patient pain. Provide appropriate postoperative care, including recognition of when postoperative analgesia and possibly antibiotic administration are indicated.

Aryl-viologen pentapeptide self-assembled conductive nanofibers.

A pentapeptide sequence was functionalized with an asymmetric arylated methyl-viologen (AVI3D2) and through controllable ß-sheet self-assembly, conductive nanofibers were formed. Using a combination of spectroscopic techniques and conductive atomic force microscopy, we investigated the molecular conformation of the resultant AVI3D2 fibers and how their conductivity is affected by ß-sheet self-assembly. These conductive nanofibers have potential for future exploration as molecular wires in optoelectronic applications.

Artificial ß-propeller protein-based hydrolases.

We developed an artificial hydrolase based on the symmetrical Pizza6 ß-propeller protein for the metal-free hydrolysis of 4-nitrophenyl acetate and butyrate. Through site-specific mutagenesis and crystallisation studies, the catalytic mechanism was investigated and found to be dependent on a threonine-histidine dyad. The mutant with additional histidine residues generated the highest kcat values, forming a His-His-Thr triad and matched previously reported metalloenzymes. The highly symmetrical ß-propeller artificial enzymes and their protein-metal complexes have potential to be utilised in bioinorganic and supramolecular chemistry, as well as being developed further into 2D/3D catalytic materials.

Effect of selective antagonists of group I metabotropic glutamate receptors on the micturition reflex in rats.

OBJECTIVE: To investigate the role of Group I metabotropic glutamate (mGlu) receptor subtypes on reflex-induced micturition in anaesthetized and conscious rats using selective mGlu1 (NPS 2407 and R214127) and mGlu5 (MPEP, MTEP, and SIB1893) allosteric antagonists. MATERIALS AND METHODS: The affinity of the compounds at mGlu1 and mGlu5 receptor subtypes was evaluated by displacement of tritiated R214127 and MPEP, respectively, from rat brain tissue. Effects of intravenous (i.v.) administration of the compounds on isovolumic bladder contractions were evaluated in anaesthetized rats. Effects of MPEP and NPS 2407 on bladder filling and voiding were evaluated by cystometry using saline or diluted (0.2%) acetic acid (MPEP only) infusion of bladders in conscious rats. RESULTS: Binding studies confirmed the selectivity of the mGlu1 (NPS 2407 and R214127) and mGlu5 (MPEP, MTEP, and SIB1893) compounds. Isovolumic bladder contractions were blocked after i.v. administration of all compounds. However, the mGlu5 antagonists were generally more potent than mGlu1 antagonists. In conscious rats with bladders infused with saline, MPEP dose-dependently and significantly increased bladder capacity starting from oral administration of 10 mg/kg. Oral administration of NPS 2407 (up to 30 mg/kg) did not induce consistent changes in bladder capacity or micturition pressure. MPEP (10 mg/kg, orally) was also evaluated in conscious rats with bladders infused with diluted acetic acid. In this model, MPEP reduced bladder instability counteracting the decrease of bladder volume capacity induced by acetic acid. There were no consistent effects on bladder contractility. CONCLUSIONS: The results indicate that i.v. and oral administration of selective mGlu5 antagonists, but not those selective for the mGlu1 subtype, have a marked inhibitory effect on reflex micturition pathways in the rat.

Metastatic Angiosarcoma of the Scalp Presenting with Cystic Lung Lesions: A Case Report and Review of Cystic Lung Diseases.

INTRODUCTION: Angiosarcomas are rare, malignant vascular tumors that affect endothelial cells of blood vessels. Angiosarcomas most commonly occur on the scalp or face of elderly individuals and are highly aggressive, with a 5-year survival rate below 15%. Cutaneous angiosarcomas often metastasize to the lung, where they can present with cystic lesions, solid lesions, pneumothorax, and/or hemothorax. CASE PRESENTATION: We report the case of an 83-year-old woman who presented with a scalp lesion, which was initially thought to be caused by scalp trauma but was later found to be an angiosarcoma. She initially refused any therapy for the tumor. She returned several months later with a cough and shortness of breath and was found to have multiple pulmonary cysts. She was treated with paclitaxel, but her tumor did not respond to the therapy and she died 2 months later. DISCUSSION: We discuss the common presentation of cutaneous angiosarcomas and their tendency to metastasize to the lung and present as cystic lesions. We also review the common conditions that can cause cystic changes in the lungs.

Identification of a nonpeptidic and conformationally restricted bradykinin B1 receptor antagonist with anti-inflammatory activity.

We report the discovery of chroman 28, a potent and selective antagonist of human, nonhuman primate, rat, and rabbit bradykinin B1 receptors (0.4-17 nM). At 90 mg/kg s.c., 28 decreased plasma extravasation in two rodent models of inflammation. A novel method to calculate entropy is introduced and ascribed approximately 30% of the gained affinity between "flexible" 4 (Ki = 132 nM) and "rigid" 28 (Ki = 0.77 nM) to decreased conformational entropy.

Potent nonpeptide antagonists of the bradykinin B1 receptor: structure-activity relationship studies with novel diaminochroman carboxamides.

The bradykinin B1 receptor is induced following tissue injury and/or inflammation. Antagonists of this receptor have been studied as promising candidates for treatment of chronic pain. We have identified aryl sulfonamides containing a chiral chroman diamine moiety that are potent antagonists of the human B1 receptor. Our previously communicated lead, compound 2, served as a proof-of-concept molecule, but suffered from poor pharmacokinetic properties. With guidance from metabolic profiling, we performed structure-activity relationship studies and have identified potent analogs of 2. Variation of the sulfonamide moiety revealed a preference for 3- and 3,4-disubstituted aryl sulfonamides, while bulky secondary and tertiary amines were preferred at the benzylic amine position for potency at the B1 receptor. Modifying the beta-amino acid core of the molecule lead to the discovery of highly potent compounds with improved in vitro pharmacokinetic properties. The most potent analog at the human receptor, compound 38, was also active in a rabbit B1 receptor cellular assay. Furthermore, compound 38 displayed in vivo activity in two rabbit models, a pharmacodynamic model with a blood pressure readout and an efficacy model of inflammatory pain.

Leukocytoclastic Vasculitis Secondary to Pyridostigmine (Mestinon): Report of a Possible First Case.

INTRODUCTION: Pyridostigmine is an acetylcholinesterase inhibitor commonly used in the treatment of myasthenia gravis. We describe a patient who developed a rash after recently being started on pyridostigmine and give a general review of leukocytoclastic vasculitis. CASE PRESENTATION: A 91-year-old man was diagnosed with ocular myasthenia gravis. He was started on pyridostigmine, and 2 weeks later he developed a rash. The rash was biopsied and found to be secondary to leukocytoclastic vasculitis; the pyridostigmine was stopped, loratadine was started, and the rash resolved. DISCUSSION: Leukocytoclastic vasculitis is commonly caused by a hypersensitivity reaction to medications, or it can be associated with certain medical conditions. We present a brief review of the most common medications and medical conditions known to cause this reaction, but to our knowledge this is the first description of pyridostigmine causing this reaction.

Drinking water additive decreases plaque and calculus accumulation in cats.

This study was performed to determine the effect of a drinking water additive on reducing plaque and calculus accumulation in cats. A two-period, parallel crossover design was used with each period consisting of a 56-day test phase. Results demonstrated that the addition of xylitol to the drinking water was effective in reducing plaque and calculus accumulation in cats.

Lactation Ketoacidosis: An Unusual Entity and a Review of the Literature.

A 31-year-old woman presented to the hospital with symptoms of nausea, malaise, and emesis. She was breastfeeding her 10-month-old infant. She was found to have severe ketoacidosis. The patient was not in diabetic ketoacidosis or alcoholic ketoacidosis; nor had she ingested any toxins. After she was admitted to the hospital, received intravenous fluids, and stopped breastfeeding, her symptoms resolved. She was found to have lactation ketoacidosis, an uncommon condition in humans. A review of all causes of ketoacidosis is presented with special emphasis on lactation ketocacidosis.

Surface-Bound Cucurbit[8]uril Catenanes on Magnetic Nanoparticles Exhibiting Molecular Recognition.

We demonstrate the preparation of surface-bound cucurbit[8]uril (CB[8]) catenanes on silica nanoparticles (NPs), where CB[8] was employed as a tethered supramolecular "handcuff" to selectively capture target guest molecules. In this catenane, CB[8] was threaded onto a methyl viologen (MV(2+) ) axle and immobilized onto silica NPs. The formation of CB[8] catenanes on NPs were confirmed by UV/Vis titration experiments and lithographic characterization, demonstrating a high density of CB[8] on the silica NPs surface, 0.56 nm(-2) . This CB[8] catenane system exhibits specific molecular recognition towards certain aromatic molecules such as perylene bis(diimide), naphthol and aromatic amino acids, and thus it can act as a nanoscale molecular receptor for target guests. Furthermore, we also demonstrate its use as an efficient and recyclable nano-platform for peptide separation. By embedding magnetic NPs inside silica NPs, separation could be achieved by simply applying an external magnetic field. Moreover, the peptides captured by the catenanes could be released by reversible single-electron reduction of MV(2+) . The entire process demonstrated high recoverability.

Oral biology and disorders of chiroptera, insectivores, monotremes, and marsupials.

Oral disease occurs in all species, from the tiny marsupial mouse to the large red kangaroo, and from the smallest mole to the largest bat. Although there has been little research done in most of the species in this article, the whole range of dental and oral diseases has been recorded, including periodontal disease, caries, and many variations in position and number of teeth. Hopefully, the interest in these species will continue and further study will enable us to understand these diseases more thoroughly.

Oral examination in the cat: a systematic approach.

PRACTICAL RELEVANCE: Oral examination in the cat is a process of observing both normal and abnormal, and should be an integral part of any wellness examination as well as a response to any specific complaint(s). The basis for an accurate diagnosis is meticulous attention to detail. It is essential that the clinician performs a whole body examination prior to examining the head and neck region. STAGES OF EXAMINATION: A thorough oral examination involves four stages. The first stage is to review the current oral problem(s) by asking questions and listening carefully to the owner's responses; gaining a thorough medical/dental history may shed more light on the current problem(s). The second stage is an extraoral physical examination to visualise and palpate the head and neck regions in the awake patient. In the third stage the clinician performs an intraoral examination in the awake patient, before proceeding to the final stage, which is an extraoral and intraoral examination under general anaesthesia. AIM: This article describes a systematic approach to the oral examination, based on these four stages. The aim of this process is not only to facilitate the making and recording of observations, but also to help avoid missing important clues that may aid in reaching a diagnosis. Common tooth pathologies in the feline patient are also briefly reviewed, paving the way for accompanying articles in this two-part Special Issue, which will provide further insight into these pathologies and discuss management approaches.