Inhibitory effects of amniotic fluid on the activated protein C anticoagulation system in maternal plasma

Journal of Thrombosis and Thrombolysis - Pulmonary thromboembolism (PTE) is one of the leading causes of maternal mortality. We previously reported that possible contamination of amniotic fluid...     

A case of cryopyrin-associated periodic fever syndrome during canakinumab administration complicated by inflammatory bowel disease

Clinical Rheumatology - Cryopyrin-associated periodic fever syndrome (CAPS) is a highly debilitating disorder, which is characterized by unregulated interleukin-1β production driven by...     

H5N1 highly pathogenic avian influenza virus isolated from conjunctiva of a whooper swan with neurological signs

An H5N1 highly pathogenic avian influenza virus was isolated from conjunctiva of a whooper swan with neurological signs, which was captured during the latest H5N1 HPAI outbreak in Japan. The conjunctival swab contained a larger amount of the virus in comparison with the tracheal swab. This is the first report on H5N1 virus isolation from the conjunctiva of a wild bird, and the result may suggest the conjunctival swab to be a critical sample for H5N1 HPAIV detection in waterfowl. Phylogenetic analysis of the HA gene indicated that the virus falls into H5N1 clade 2.3.2.1.     

Low-dose Interferon-α Treatment Improves Survival and Inflammatory Responses in a Mouse Model of Fulminant Acute Respiratory Distress Syndrome

Acute respiratory distress syndrome (ARDS) is accompanied by severe lung inflammation induced by various diseases. Despite the severity of symptoms, therapeutic strategies for this pathologic condition are still poorly developed. Interferon (IFN)-α is well known as an antiviral cytokine and low-dose IFN-α has been reported to show antiinflammatory effects. Therefore, we investigated how this cytokine affected ARDS in a mouse model. C57BL/6 mice received sequential intratracheal administration of α-galactosylceramide (α-GalCer) and lipopolysaccharide (LPS), which resulted in the development of fulminant ARDS. These mice were then treated intranasally with IFN-α and their survival, lung weight, pathological findings, and cytokine production were evaluated. Administration of low-dose IFN-α prolonged survival of fulminant ARDS mice, but higher doses of IFN-α did not. Histological analysis showed that low-dose IFN-α treatment improved findings of diffuse alveolar damage in fulminant ARDS mice, which was associated with reduction in the wet/dry (W/D) lung weight ratio. Furthermore, IFN-γ production in the lungs was significantly reduced in IFN-α-treated mice, compared with control mice, but tumor necrosis factor (TNF)-α production was almost equivalent for both groups. Low-dose IFN-α shows antiinflammatory and therapeutic effects in a mouse model of fulminant ARDS, and reduced production of IFN-γ in the lung may be involved in the beneficial effect of this treatment.     

Accessory mandibular foramina: a CT study of 300 cases

Purpose

The aim of the study was to assess the distribution of accessory foramina in the mandibular body with computed tomography (CT).

Materials and methods

The CT images of the mandibular body in 300 subjects (183 females and 117 males aged between 12 and 85 years) were retrospectively analysed for the presence of accessory foramina. The buccal and lingual surfaces were examined by dividing them into anterior and posterior quadrants.

Results

Of the 300 subjects, 26 presented with accessory foramina on buccal posterior aspect and 70 subjects presented on buccal anterior aspect. Further, on the lingual posterior aspect, 132 subjects presented with accessory foramina and 59 subjects presented on lingual anterior aspect. Most of the subjects with accessory foramina in the buccal posterior, buccal anterior and lingual anterior regions had accessory foramina on other aspects of the mandible as well.

Conclusion

A substantial number of subjects presented with accessory foramina on the lingual posterior aspect when compared to other aspects. Nevertheless, the number of subjects with accessory foramina on other aspects of the mandible was considerable and cannot be ignored. It is suggested that when an accessory foramen is identified in an individual on a particular aspect of the mandibular body, it is highly probable that he will exhibit accessory foramina on other aspects as well.     

Stereoselective synthesis of Gly-Gly-type (E)-methylalkene and (Z)-chloroalkene dipeptide isosteres and their application to 14-mer RGG peptidomimetics

Stereoselective and efficient synthesis of Gly-Gly-type (E)-methylalkene and (Z)-chloroalkene dipeptide isosteres is realized by organocuprate-mediated single electron transfer reduction. The synthetic isosteres can be used in Fmoc-based solid phase peptide synthesis, resulting in the preparation of the 14-mer RGG peptidomimetics containing an (E)-methylalkene or a (Z)-chloroalkene unit.

An efficient synthesis of Gly-Gly-type (E)-methylalkene and (Z)-chloroalkene dipeptide isosteres is realized by organocuprate-mediated single electron transfer reduction.

Glycylglycine (Gly-Gly) is the smallest dipeptide and has been synthesized by many approaches in the last 100 years.¹ Due to its versatile nature and ready availability, glycylglycine has been used as a chemical probe² and buffer³ in biochemical studies and also as a reagent which can enhance the solubility of overexpressed proteins.⁴ In addition to the utility of Gly-Gly itself, oligoglycine (oligo-Gly) motifs are notable for being more flexible and less-functionalized than any combination of other amino acids. These features are useful in bioconjugation strategies which link multiple biomolecules without interfering with the function of each biomolecule, allowing synthesis of bioconjugated artificial molecules including dimeric, multi-domain, and fusion proteins.⁵ The flexibility of oligo-Gly enables the formation of unusual secondary structures of peptides and proteins.⁶ Thus, the oligo-Gly motif can be found in the biologically important peptides and proteins such as Met/Leu-enkephalin ( and ), the C-terminus of ubiquitin , ctenidin,⁷ shepherin I,⁸ and DNA/RNA-binding proteins with repeated sequences related to the various physiological processes via protein–protein and protein–nucleic acids interactions.⁹ These proteins relate with gene expression, DNA damage signal and apoptosis, however, the detail effects of Gly-Gly with steric and electronic factors to these functions are unknown. Given the importance of oligo-Gly in various fields, non-hydrolyzable peptidomimetics of oligo-Gly could be attractive building blocks for the synthesis of novel bioconjugated molecules and complex peptidomimetics with improved chemical stability and functionality. For example, even the Gly-Gly dipeptide mimic with the tetra-substituted alkene unit replacing the Gly-Gly peptide bond has been shown to promote the β-hairpin formation, and is thus the smallest peptidomimetic that is known to control a peptide structure.¹⁰ There are two reports of the synthesis of Gly-Gly-type fluoroalkene dipeptide isosteres.¹¹ However, the poor synthetic access to such molecules has hindered their application to the peptidomimetics. Our long-standing interest in the drug discovery with amide-to-alkene isosteric switching prompted this investigation into the stereoselective synthesis of Gly-Gly-type (E)-methylalkene and (Z)-chloroalkene dipeptide isosteres.In this report, we describe the beginning of our oligo-Gly-based peptidomimetic study with the stereoselective synthesis of Gly-Gly-type (E)-methylalkene and (Z)-chloroalkene dipeptide isosteres and their use in Fmoc-based solid phase peptide synthesis (SPPS). In the first application of isosteres of this type to access complex peptidomimetics, we synthesize 14-mer RGG peptidomimetics containing (E)-methylalkene or (Z)-chloroalkene unit as surrogates for a Gly-Gly peptide bond. These two isosteres were selected because the potentials of both isosteres have not been fully uncovered, though there are several promising examples.^12,13 Since the carbonyl oxygen equivalents of those isosteres are similar in their size¹⁴ but differ in their electronic properties,¹⁵ comparative studies of these isosteres would have the advantage of exploring the role of peptide bonds in terms of their steric and electronic natures. This work also uncovered the unique ability of the Gly-Gly-type (Z)-chloroalkene isostere to induce β-turn structures in the almost unfoled peptides (Fig. 1).Open in a separate windowFig. 1Gly-Gly peptide and its alkene-type peptidomimetics.The main challenges in this study include the stereoselective formation of the (E)-methylalkene and (Z)-chloroalkene moieties as the surrogates of the Gly-Gly trans-peptide bond, together with the control of the olefine isomerization under the condition of the isostere synthesis and Fmoc-based SPPS. There are several synthetic approaches toward tri-substituted alkene-type isosteres, including the Overman rearrangement,¹³ the S_N2′-type opening of alkenylaziridines,^12a Cu-mediated CF₃-coupling of vinyl iodide,¹⁶ and cross-couplings of vinyl stannane.¹⁷ Organocuprate-mediated reactions of α,β-unsaturated carbonyl compounds with γ-leaving group(s) are also powerful methods to produce tri-substituted alkene-type isosteres, and are particularly suitable for the stereoselective synthesis of (Z)-fluoroalkene¹⁸ and (Z)-chloroalkene isosteres.¹⁹The preparation of Gly-Gly-type alkene dipeptide isosteres was facilitated by the organocuprate-mediated SET reduction that was used in the stereoselective formation of the (E)-methylalkene and (Z)-chloroalkene moieties. Scheme 1 shows the synthesis of (E)-methylalkene isosteres (5). A Witting reaction of methacrolein (1) with ethyl (triphenylphosphoranylidene)acetate followed by epoxidation with m-CPBA afforded the alkenyl oxirane (2) which, treated with Gillman reagent (n-Bu₂CuLi), produced the allylic alcohol (3) with high E-selectivity. A Mitsunobu reaction of 3 with Ns(Boc)NH and deprotection provided the Gly-Gly-type (E)-methylalkene dipeptide isostere 5 that can be applied to the Fmoc-based SPPS. All reactions leading to the synthesis of 5 were performed on a gram scale.Open in a separate windowScheme 1Synthesis of Gly-Gly-type (E)-methylalkene dipeptide isosteres (5).Synthesis of chloroalkene isostere (14) is shown in Scheme 2. Based on previous results for the successful, efficient synthesis of Val-Xaa-type chloroalkene isosteres,^19c we assumed that a similar protocol would allow for the synthesis of 14. However, our attempts revealed that the Gly substrate used has different reactivity and selectivity compared to the other substrates, particularly in the SET reduction step. Consequently, Gly-specific reaction conditions are necessary. The nucleophilic addition of the lithium enolate of methyl dichloroacetate to the N-sulfinylaldimine (7), prepared from (±)-tert-butylsulfinamide (6) and paraformaldehyde and m-CPBA oxidation of 6 gave the N-tert-butylsulfonyl (Bus)-protected α,α-dichloro-β-amino ester (8). Precise control of the amount of DIBAL-H at low temperatures enables the partial reduction of 8, and this is followed by a Horner–Wadsworth–Emmons reaction to produce the corresponding (E)-enoate (9). Initial efforts to apply our established conditions for SET reduction with Me₂CuLi identified the poor Z-selectivity of the reaction and also its propensity to form the α-methylated side products 11 and 12 (Open in a separate windowScheme 2Synthesis of Gly-Gly-type (Z)-chloroalkene dipeptide isosteres (14).Reactivity of (E)-enoate (9) with organocuprates^a