Separation of D- and L-amino acids by ion exchange column chromatography in the form of alanyl dipeptides

Summary A method of ion exchange column chromatography was developed for the determination of D- and L-amino acids in the form of diastereomeric dipeptide. First the protein containing samples were hydrolyzed with 6 molar hydrochloric acid, then the single amino acids were separated in an LKB automated amino acid analyzer with the LKB fraction collector. Following lyophilization, the single amino acids were transformed into alanyl dipeptides with tertiary-butyloxycarbonil-L-alanine-N-hydroxy-succinimide (t-BOC-L-Ala-ONSu) active ester. The alanyl dipeptides were easily separated from one another and the initial amino acids. Determination of the D- and L-amino acids in this form is relatively accurate and reproducible but takes some time (33–38 min). Accuracy of the determination is satisfactory. The coefficient of variation amounts to 3–5%. The use of the method is suggested to laboratories having an amino acid analyzer and wish to determine D-and L-amino acids in synthetic-amino acids complements, peptides or natural materials.     

An in situ collagen-HA hydrogel system promotes survival and preserves the proangiogenic secretion of hiPSC-derived vascular smooth muscle cells

Human-induced pluripotent stem cell-derived vascular smooth muscle cells (hiPSC-VSMCs) with proangiogenic properties have huge therapeutic potential. While hiPSC-VSMCs have already been utilized for wound healing using a biomimetic collagen scaffold, an in situ forming hydrogel mimicking the native environment of skin offers the promise of hiPSC-VSMC mediated repair and regeneration. Herein, the impact of a collagen type-I-hyaluronic acid (HA) in situ hydrogel cross-linked using a polyethylene glycol-based cross-linker on hiPSC-VSMCs viability and proangiogenic paracrine secretion was investigated. Our study demonstrated increases in cell viability, maintenance of phenotype and proangiogenic growth factor secretion, and proangiogenic activity in response to the conditioned medium. The optimally cross-linked and functionalized collagen type-I/HA hydrogel system developed in this study shows promise as an in situ hiPSC-VSMC carrier system for wound regeneration.     

Multicenter evaluation of the phosphorylcholine-coated biodivYsio stent in short de novo coronary lesions: The SOPHOS study

AIMS: The BiodivYsio trade mark stent (Biocompatibles Ltd, Farnham, UK) is coated with a phosphorylcholine (PC)-containing copolymer to confer biocompatibility. The SOPHOS (Study Of PHosphorylcholine coating On Stents) study was designed to assess the safety and efficacy of this novel coronary stent and by indirect comparison to indicate equivalence with other formal stent studies. METHODS AND RESULTS: Patients with angina and a single short (#x2A7F;12 mm) de novo lesion in a native coronary artery of >/=2.75 mm diameter were included. A total of 425 patients were allocated in 24 centers. Clinical data were collected at one-, six- and nine-month follow-up. Angiography was performed before and after the stent implantation. In addition, in the first 200 patients (SOPHOS A) angiography was routinely performed at six months. The following 225 patients (SOPHOS B) were merely followed up clinically. The primary end-point of the study, the six-month MACE-rate (MACE = Major Adverse Cardiac Events) was 13.4% (two cardiac death; five Q-wave/nine non-Q-wave myocardial infarctions (MI); nine CABG and 32 target lesion revascularization (TLR), which is similar to the calculated 15% MACE-rate in comparable reference studies. Secondary end-points included among others restenosis at six months in the SOPHOS A population. The target vessel diameter was 2.98 +/- 0.48 mm. Minimal lumen diameter pre/post procedure and at follow-up was 1.00 +/- 0.32, 2.69 +/- 0.37, 1.91 +/- 0.71 mm, respectively. The binary restenosis rate (>/=50% diameter stenosis at follow-up) was 17.7%. CONCLUSION: The coronary BiodivYsio stent is safe and effective as a primary device for the treatment of native coronary artery lesions in patients with stable or unstable angina pectoris. Clinical and angiographic results are in the statistical range of equivalence with comparable studies with other current stents.     

Soluble P-selectin moderates complement-dependent reperfusion injury of ischemic skeletal muscle

P-selectin is an adhesion molecule expressed on activated endothelial and platelet surfaces. The function of the short consensus repeats (SCRs) of P-selectin, homologous with the SCRs of complement regulatory proteins is largely unknown. In a model of murine hindlimb ischemia where local reperfusion injury is partly mediated by IgM natural antibody and classical complement pathway activation, we hypothesized that human soluble P-selectin (sP-sel) would moderate the complement component of the inflammatory response. Infusion of sP-sel supernatant or purified (p) sP-sel prepared from activated human platelets, reduced ischemic muscle vascular permeability by 48% and 43%, respectively, following reperfusion. Hindlimb immunohistochemistry demonstrated negligible C3 staining colocalized with IgM in these groups compared with intense staining in the untreated injured mice. In vitro studies of mouse serum complement hemolytic activity showed that psP-sel inhibited the classical but not alternative complement pathway. Flow cytometry demonstrated that psP-sel inhibited C1q adherence to sensitized red blood cells. From these data we conclude that sP-sel moderates skeletal muscle reperfusion injury by inhibition of the classical complement pathway.     

A new fourier transform approach for protein coding measure based on the format of the Z curve

MOTIVATION: At the core of most protein gene-finding algorithms are the coding measures used to make a decision on coding/non-coding. Of the protein coding measures, the Fourier measure is one of the most important. However, due to the limited length of the windows usually used, the accuracy of the measure is not satisfactory. This paper is devoted to improving the accuracy by lengthening the sequence to amplify the periodicity of 3 in the coding regions. RESULTS: A new algorithm is presented called the lengthen-shuffle Fourier transform algorithm. For the same window length, the percentage accuracy of the new algorithm is 6-7% higher than that of the ordinary Fourier transform algorithm. The resulting percentage accuracy (average of specificity and sensitivity) of the new measure is 84.9% for the window length 162 bp. AVAILABILITY: The program is available on request fromC.- T. Zhang. Contact: ctzhang@tju.edu.cn      

Bioinspired polymers that control intracellular drug delivery

One of the important characteristics of biological systems is their ability to change important properties in response to small environmental signals. The molecular mechanisms that biological molecules utilize to sense and respond provide interesting models for the development of “smart” polymeric biomaterials with biomimetic properties. An important example of this is the protein coat of viruses, which contains peptide units that facilitate the trafficking of the virus into the cell via endocytosis, then out of the endosome into the cytoplasm, and from there into the nucleus. We have designed a family of synthetic polymers whose compositions have been designed to mimic specific peptides on viral coats that facilitate endosomal escape. Our biomimetic polymers are responsive to the lowered pH within endosomes, leading to disruption of the endosomal membrane and release of important biomolecular drugs such as DNA, RNA, peptides and proteins to the cytoplasm before they are trafficked to lysosomes and degraded by lysosomal enzymes. In this article, we review our work on the design, synthesis and action of such smart, pH-sensitive polymers.     

The morphology and electrophysiology of the neurones of the paired pedal ganglia of Lymnaea stagnalis (L.)

1. A morphological and electrophysiological map of the identifiable neurones and neuronal clusters of the paired pedal ganglia has been prepared. 2. Neuronal morphology was investigated using the fluorescent dye, Lucifer Yellow CH, whilst electrophysiological properties were studied using conventional intracellular recording techniques and the phase plane technique. 3. The paired pedal ganglia are largely symmetrical and giant neurones usually have contralateral homologues. 4. Neuronal clusters are also paired, but minor asymmetries, both of identifiable neurones and neuronal clusters have been found to exist. 5. These asymmetries are thought to be related to asymmetries of body form. 6. Most of the individually identifiable neurones possess obligatory axon branches which are invariant from one preparation to the next, but variant branches also occur. 7. Within the neuronal clusters, morphology appears to be more variable. 8. Individually identifiable neurones and neuronal clusters were characterized electrophysiologically according to the criteria of action potential shape, spontaneous activity pattern, electrical coupling and common synaptic inputs. 9. Homologous pairs of neurones usually have similar electrophysiological properties, as do those within clusters. 10. A number of wide-acting synaptic inputs have been identified on neurones of the pedal, buccal, visceral and parietal ganglia.     

Assessment of the efficiency of a hand-held suction device for sampling spiders: improved density estimation or oversampling?

In the study a comparison is made between the results of two sampling procedures, both based on the application of the same hand-held suction apparatus. Sampling was aimed at spiders, and was carried out on two alfalfa fields. In the first method suction sampling was applied to an enclosure of 0.48 m². The enclosed area was sampled intensively, which was facilitated by the removal of the vegetation. The second method was a transect sampling procedure during which the suction apparatus with a 0.01 m² nozzle was applied to single unenclosed sampling points 1 m apart. A linear series of 48 such subsamples comprised a transect, thus the total area covered in a transect equalled the area of the enclosure. In the transect samples three times more spiders were caught than in the enclosures. This result was consistent on different occasions and at both fields. This basic trend was found in all spider families that were present in significant numbers in the samples. Species composition in the samples collected by the two methods was similar, and species abundance ranks were highly correlated across dates. We propose that an “edge effect” can explain higher catches in transect samples. This edge effect is caused by lateral suction at the edges, which inflated the number of animals caught in the transect application.