Phosphopeptide-dependent labeling of 14-3-3 ζ proteins by fusicoccin-based fluorescent probes

Fluorescent combination: Cell-penetrating probes derived from the diterpene fusicoccin can form ternary complexes with 14-3-3 proteins and phosphopeptide ligands, whereupon the probes site-specifically attach a fluorescent tag onto the surface of the 14-3-3 proteins.     

PEGylation of an artificial O2 and CO receptor: synthesis, characterisation and pharmacokinetic study

A synthetic oxygen (O(2)) and carbon monoxide (CO) receptor (hemoCD) composed of 5,10,15,20-tetrakis(4-sulfonatophenyl)porphinatoiron(ii) and a per-O-methylated β-cyclodextrin dimer with a pyridine linker (Py3CD) was functionalised with poly(ethylene glycol) (PEG) to elongate the circulation time of the receptor in the bloodstream. α-PEG monocarboxylic acid (HOOC(CH(2))(3)(CO)O-PEG(mw)-OCH(3); mw = 750 or 5k) or α,ω-PEG dicarboxylic acid (HOOC(CH(2))(3)(CO)O-PEG(mw)-O(CO)(CH(2))(3)COOH; mw = 10k or 20k) was reacted with the amino group of 5-(4-aminophenyl)-10,15,20-tris(4-sulfonatophenyl)porphyrin to afford a porphyrin monomer having a PEG chain or a porphyrin dimer having a PEG linker, respectively. The ferrous complexes of these PEGylated porphyrins (PEG750-, PEG5k-, PEG10k- and PEG20k-hemoCDs) bound O(2) in aqueous solution, P(1/2) values being 6.5-8.1 Torr at pH 7.0 and 25 °C. Each PEG(mw)-hemoCD was infused into the femoral vein of a Wistar male rat. After 6 h of the infusions, 67, 82, 86 and 42% of PEG750-, PEG5k-, PEG10k- and PEG20k-hemoCD were excreted in the urine. PEG750-hemoCD with a hydrodynamic diameter (D(h)) of 3.4 nm seemed to partly leak from the blood vessels (pore size: 2-6 nm) before renal filtration (pore size: 4-14 nm). PEG5k- (D(h) = 6.2 nm) and PEG10k-hemoCDs (9.0 nm) hardly passed through the blood vessels but were fully filtered by the kidney, resulting in high excretion rates. A considerable amount of PEG20k-hemoCD (D(h) = 12.0 nm) was retained in the blood even at 6 h after administration. The present study demonstrates that the behaviour of hemoCD in blood after administration can be controlled by modification of hemoCD with PEG having an appropriate molecular weight.     

Unnatural base pair systems toward the expansion of the genetic alphabet in the central dogma

Toward the expansion of the genetic alphabet of DNA, several artificial third base pairs (unnatural base pairs) have been created. Synthetic DNAs containing the unnatural base pairs can be amplified faithfully by PCR, along with the natural A-T and G-C pairs, and transcribed into RNA. The unnatural base pair systems now have high potential to open the door to next generation biotechnology. The creation of unnatural base pairs is a consequence of repeating "proof of concept" experiments. In the process, initially designed base pairs were modified to address their weak points. Some of them were artificially evolved to ones with higher efficiency and selectivity in polymerase reactions, while others were eliminated from the analysis. Here, we describe the process of unnatural base pair development, as well as the tests of their applications.(Communicated by Takao SEKIYA, M.J.A.).     

Molecular recognition of ketomalonates by asymmetric aldol reaction of aldehydes with secondary-amine organocatalysts

A diastereo- and enantioselective aldol reaction between aldehydes and a synthetically useful ketomalonate 1c as a hydrated form was developed, and either anti- or syn-aldol adducts having a chiral tetrasubstituted carbon center were obtained in high enantioselectivities by use of a tetrazole analogue of L-proline (S)-2 or an axially chiral amino sulfonamide (S)-3 as catalyst.     

Triterpene saponins with hyaluronidase inhibitory activity from the seeds of Camellia sinensis

The MeOH extract of the seeds of Camellia sinensis (L.) KUNTZE gave twelve new saponins (1-12) along with ten known saponins (13-22). These saponins (1-22) showed stronger hyaluronidase inhibitory activity than the positive control, rosmarinic acid.     

Chiral recognition of helical metal complexes by modified cyclodextrins.

Chirality of metal complexes M(phen)3(n+) (M = Ru(II), Rh(III), Fe(II), Co(II), and Zn(II), and phen = 1,10-phenanthroline) is recognized by heptakis(6-carboxymethylthio-6-deoxy)-beta-cyclodextrin heptaanion (per-CO2(-)-beta-CD) and hexakis(2,3,6-tri-O-methyl)-alpha-cyclodextrin (TMe-alpha-CD) in D2O. The binding constant (K) for the Delta-Ru(phen)3(2+) complex of per-CO2(-)-beta-CD (K = 1250 M(-1)) in 0.067 M phosphate buffer at pD 7.0 is approximately 2 times larger than that for the Lambda-isomer (590 M(-1)). Definite effects of inorganic salts on stability of the complexes indicate a large contribution of Coulomb interactions to complexation. The fact that hydrophilic Ru(bpy)3(2+) (bpy = 2,2'-bipyridine) does not form a complex with per-CO2(-)-beta-CD suggests the importance of inclusion of the guest molecule into the host cavity for forming a stable ion-association complex. The positive entropy change for complexation of Ru(phen)3(2+) with per-CO2(-)-beta-CD shows that dehydration from both the host and the guest occurs upon complexation. Similar results were obtained with trivalent Rh(phen)3(3+) cation. Pfeiffer effects were observed in complexation of racemic Fe(phen)3(2+), Co(phen)3(2+), and Zn(phen)3(2+) with per-CO2(-)-beta-CD with enriched Delta-isomers. Native cyclodextrins such as alpha-, beta-, and gamma-cyclodextrins as well as heptakis(2,3,6-tri-O-methyl)-beta-cyclodextrin do not interact with Ru(bpy)3(2+). However, hexakis(2,3,6-tri-O-methyl)-alpha-cyclodextrin (TMe-alpha-CD) interacts with Ru(phen)3(2+) and Ru(bpy)3(2+) and discriminates between the enantiomers of these metal complexes. The K values for the Delta- and Lambda-Ru(phen)3(2+) ions are 54 and 108 M(-1), respectively. Complexation of the Delta- and Lambda-isomers of Ru(phen)3(2+) with TMe-alpha-CD is accompanied by negative entropy changes, suggesting that cationic Ru(phen)3(2+) is shallowly included into the cavity of the neutral host through van der Waals interactions. The Delta-enantiomer, having a right-handed helix configuration, fits the primary OH group side of per-CO2(-)-beta-CD (SCH2CO2(-) side) well, while the Lambda-enantiomer, having a left-handed helix configuration, is preferably bound to the secondary OH group side of TMe-alpha-CD. The asymmetrically twisted shape of a host cavity seems to be the origin of chiral recognition by cyclodextrin.     

Computer-Aided Detection of Quantitative Signatures for Breast Fibroepithelial Tumors Using Label-Free Multi-Photon Imaging

Fibroadenomas (FAs) and phyllodes tumors (PTs) are major benign breast tumors, pathologically classified as fibroepithelial tumors. Although the clinical management of PTs differs from FAs, distinction by core needle biopsy diagnoses is still challenging. Here, a combined technique of label-free imaging with multi-photon microscopy and artificial intelligence was applied to detect quantitative signatures that differentiate fibroepithelial lesions. Multi-photon excited autofluorescence and second harmonic generation (SHG) signals were detected in tissue sections. A pixel-wise semantic segmentation method using a deep learning framework was used to separate epithelial and stromal regions automatically. The epithelial to stromal area ratio and the collagen SHG signal strength were investigated for their ability to distinguish fibroepithelial lesions. An image segmentation analysis with a pixel-wise semantic segmentation framework using a deep convolutional neural network showed the accurate separation of epithelial and stromal regions. A further investigation, to determine if scoring the epithelial to stromal area ratio and the SHG signal strength within the stromal area could be a marker for differentiating fibroepithelial tumors, showed accurate classification. Therefore, molecular and morphological changes, detected through the assistance of computational and label-free multi-photon imaging techniques, enable us to propose quantitative signatures for epithelial and stromal alterations in breast tissues.     

Bias reduction using surrogate endpoints as auxiliary variables

Annals of the Institute of Statistical Mathematics - Recently, it is becoming more active to apply appropriate statistical methods dealing with missing data in clinical trials. Under not missing at...     

Sub-transition phenomenon of the “L-dipalmitoyl phosphatidylcholine - water” system: Effect of water content and its aggregation state

Thermoanalytical investigations on the two component system of L-dipalmitoyl phosphatidylcholine and water revealed that the sub-transition in the present system is remarkably affected by the water content as well as the condition of annealing treatment and also that the stable low-temparature phase obtained after the appropriate annealing shows the existence of the more loosely-bound water than that in the super-cooled L_β′ phase.     

Thermodynamic studies on the interaction between nucleic acid and drug by calorimetry

The heats of mixing of the DNA-AD, Duplex I-AD and Duplex II-one systems were measured at 298.15 ± 0.005 K by using an LKB batch type twin microcalorimeter with a help of spectral measurements. From the results of DNA-AD system obtained, the interaction between DNA and AD is mainly caused by intercalation manner by referring to the result of spectral measurement. And, we estimated the thermodynamic quantities based on the intercalation process. While, from the results of Duplex I-AD and Duplex II-one systems, we concluded that the interactions of these systems may be corresponded to an electrostatic force as binding process rather than an intercalation process.