Hydrogenation of polycyclic aromatic hydrocarbons as a factor affecting the cosmic 6.2 micron emission band.

While many of the characteristics of the cosmic unidentified infrared (UIR) emission bands observed for interstellar and circumstellar sources within the Milky Way and other galaxies, can be best attributed to vibrational modes of the variants of the molecular family known as polycyclic aromatic hydrocarbons (PAH), there are open questions that need to be resolved. Among them is the observed strength of the 6.2 micron (1600 cm(-1)) band relative to other strong bands, and the generally low strength for measurements in the laboratory of the 1600 cm(-1) skeletal vibration band of many specific neutral PAH molecules. Also, experiments involving laser excitation of some gas phase neutral PAH species while producing long lifetime state emission in the 3.3 micron (3000 cm(-1)) spectral region, do not result in significant 6.2 micron (1600 cm(-1)) emission. A potentially important variant of the neutral PAH species, namely hydrogenated-PAH (H(N)-PAH) which exhibit intriguing spectral correlation with interstellar and circumstellar infrared emission and the 2175 A extinction feature, may be a factor affecting the strength of 6.2 micron emission. These species are hybrids of aromatic and cycloalkane structures. Laboratory infrared absorption spectroscopy augmented by density function theory (DFT) computations of selected partially hydrogenated-PAH molecules, demonstrates enhanced 6.2 micron (1600 cm(-1)) region skeletal vibration mode strength for these molecules relative to the normal PAH form. This along with other factors such as ionization or the incorporation of nitrogen or oxygen atoms could be a reason for the strength of the cosmic 6.2 micron (1600 cm(-1)) feature.

Screening for oligonucleotide binding affinity by a convenient fluorescence competition assay.

A competitive homogeneous quenched fluorescence assay system is described for the high throughput screening of DNA conjugates that bind to single-stranded DNA. Fluorescence signal is generated by competitive binding of the sample molecule to a target strand labelled with a quencher probe, which is otherwise hybridised to a complementary strand containing a fluorescent probe. Thus fluorescence generated is related to the affinity of the sample. Competitive analysis of a number of peptide-oligonucleotide conjugates gave data that correlated well with the corresponding UV melting data. The assay will be useful for screening of large numbers of potential single-stranded binding molecules.

Inhibition of human telomerase by PNA-cationic peptide conjugates.

The inhibition of human telomerase has been explored using peptide conjugated derivatives of a PNA pentamer directed at the RNA template of telomerase. It is demonstrated that the presence of cationic peptides at the N-terminus of the PNA results in enhanced inhibition of telomerase activity. Furthermore, inhibition depended on the specificity of PNA recognition.

Pro-inflammatory cytokines stimulate mitogen-activated protein kinase subfamilies, increase phosphorylation of c-Jun and ATF2 and upregulate c-Jun protein in neonatal rat ventricular myocytes.

Pro-inflammatory cytokines may be important in the pathophysiological responses of the heart. We investigated the activation of the three mitogen-activated protein kinase (MAPK) subfamilies ¿c-Jun N-terminal kinases (JNKs), p38-MAPKs and extracellularly-responsive kinases (ERKs) by interleukin-1 beta (IL-1 beta) or tumour necrosis factor alpha (TNF alpha) in primary cultures of myocytes isolated from neonatal rat ventricles. Both cytokines stimulated a rapid (maximal within 10 min) increase in JNK activity. Although activation of JNKs by IL-1 beta was transient returning to control values within 1 h, the response to TNF alpha was sustained. IL-1 beta and TNF alpha also stimulated p38-MAPK phosphorylation, but the response to IL-1 beta was consistently greater than TNF alpha. Both cytokines activated ERKs, but to a lesser degree than that induced by phorbol esters. The transcription factors, c-Jun and ATF2, are phosphorylated by the MAPKs and are implicated in the upregulation of c-Jun. IL-1 beta and TNF alpha stimulated the phosphorylation of c-Jun and ATF2. However, IL-1 beta induced a greater increase in c-Jun protein. Inhibitors of protein kinase C (PKC) (Ro318220, GF109203X) and the ERK cascade (PD98059) attenuated the increase in c-Jun induced by IL-1 beta, but LY294002 (an inhibitor of phosphatidylinositol 3' kinase) and SB203580 (an inhibitor of p38-MAPK, which also inhibits certain JNK isoforms) had no effect. These data illustrate that some of the pathological effects of IL-1 beta and TNF alpha may be mediated through the MAPK cascades, and that the ERK cascade, rather than JNKs or p38-MAPKs, are implicated in the upregulation of c-Jun by IL-1 beta.

Synthesis and hybridization analysis of a small library of peptide-oligonucleotide conjugates.

A small library of 49 peptide-oligonucleotide conjugates were synthesized to explore the influence of various peptide side chains on the hybridization properties of the DNA. An invariant 8mer oligonucleotide was coupled to a peptide portion that contained a five residue variable region composed of the cationic amino acids lysine, ornithine, histidine and arginine, the hydrophobic amino acid tryptophan, and alanine as a spacer. Melting temperature analysis indicated that T m depended principally on the number of cationic residues. The free energies of binding for polycationic peptide-oligonucleotides were enhanced compared with the unmodified 8mer. The origin of this stabilizing effect was found to be derived from a more exothermic enthalpic term. Improvement in Delta G vH was found to depend on the presence of positive charge and also the exact identity of the cationic amino acid, with the polyarginine peptide giving the most favourable Delta G vH value and the most exothermic Delta H vH. Further exploration suggested that the cationic peptide fragments interacted mainly with single-stranded rather than duplex DNA. A study of pH dependence showed that the polyhistidine conjugate was particularly sensitive to pH changes near neutrality, as indicated by a significant rise in T m from 19.5 degrees C at pH 8.0 to 28.5 degrees C at pH 6.0.

Accuracy of fingerstick glucose values in shock patients.

BACKGROUND: Fingerstick blood glucose measurement has become widespread in both hospital and prehospital settings. OBJECTIVE: To determine the accuracy of fingerstick blood glucose measurement in patients with poor peripheral perfusion (shock). METHOD: Results obtained during three methods of glucose analysis (fingerstick blood glucose measurement; bedside and laboratory glucose analysis) were examined prospectively on 38 patients from inpatient medical and surgical critical care units or the emergency department of a large tertiary care referral center. RESULTS: The means of the three glucose measurements were significantly different. Univariate analysis of the mean laboratory glucose value versus the mean fingerstick glucose value was significantly different. The mean venipuncture glucose measured by the bedside glucose meter versus the mean venous laboratory glucose was not significantly different. CONCLUSION: These results suggest that fingerstick blood samples should not be used for bedside glucose analysis in patients who may have inadequate tissue perfusion.