Preparation of a novel core-shell nanostructured gold colloid-silk fibroin bioconjugate by the protein in situ redox technique at room temperature

A novel core-shell gold colloid-silk fibroin (SF) bioconjugate was prepared by the protein in situ redox technique at room temperature, in which the tyrosine (Tyr) residue of the SF, having strong electron donating properties, in situ reduced Au(III) ions to Au colloids showing a stable and highly monodispersed nature.

Severe and moderate haemophilia A and B in US females

Haemophilia A and B are rare X-lined hemorrhagic disorders that typically affect men. Women are usually asymptomatic carriers, but may be symptomatic and, rarely, also express severe (factor VIII (FVIII) or factor IX (FIX) <0.01 U mL(-1)) or moderately severe (FVIII/FIX 0.01-0.05 U mL(-1)) phenotypes. However, data on clinical manifestations, genotype and the psychosocial ramifications of illness in severely affected females remain anecdotal. A national multi-centre retrospective study was conducted to collect a comprehensive data set on affected US girls and women, and to compare clinical observations to previously published information on haemophilic males of comparable severity and mildly affected haemophilic females. Twenty-two severe/moderate haemophilia A/B subjects were characterized with respect to clinical manifestations and disease complications; genetic determinants of phenotypic severity; and health-related quality of life (HR-QoL). Clinical data were compared as previously indicated. Female patients were older than male patients at diagnosis, but similarly experienced joint haemorrhage, disease- and treatment-related complications and access to treatment. Gynaecological and obstetrical bleeding was unexpectedly infrequent. F8 or F9 mutations, accompanied by extremely skewed X-chromosome inactivation pattern (XIP), were primary determinants of severity. HR-QoL was diminished by arthropathy and viral infection. Using systematic case verification of participants in a national surveillance registry, this study elucidated the genetics, clinical phenotype and quality of life issues in female patients with severe/moderate haemophilia. An ongoing international case-controlled study will further evaluate these observations. Novel mechanistic questions are raised about the relationship between XIP and both age and tissue-specific FVIII and FIX expression.

Regio- and stereoselective synthesis of benzothiazolo-pyrimidinones via an NHC-catalyzed Mannich/lactamization domino reaction

An NHC-catalyzed regio- and stereoselective Mannich/lactamization domino reaction of N-(benzothiazolyl)imines with α-chloroaldehydes has been developed.

An NHC-catalyzed regio- and stereoselective Mannich/lactamization domino reaction of N-(benzothiazolyl)imines with α-chloroaldehydes has been developed. This new protocol provides a facile approach for the asymmetric synthesis of benzothiazolo-pyrimidinones and a pyrrolo[1,2-a]indolone in moderate to good yields (34–78%) and excellent stereoselectivities (87–99% ee, up to >20 : 1 d.r.).

Insights into nucleotide binding in protein kinase A using fluorescent adenosine derivatives

The binding of the methylanthraniloyl derivatives of ATP (mant-ATP), ADP (mant-ADP), 2'deoxyATP (mant-2'deoxyATP), and 3'deoxyATP (mant-3'deoxyATP) to the catalytic subunit of protein kinase A was studied to gain insights into the mechanism of nucleotide binding. The binding of the mant nucleotides leads to a large increase in fluorescence energy transfer at 440 nm, allowing direct measurements of nucleotide affinity. The dissociation constant of mant-ADP is identical to that for ADP, while that for mant-ATP is approximately threefold higher than that for ATP. The dissociation constant for mant-3'deoxyATP is approximately fivefold higher than that for 3'deoxyATP while derivatization of 2'deoxyATP does not affect affinity. The time-dependent binding of mant-ATP, mant-2'deoxyATP, and mant-ADP, measured using stopped-flow fluorescence spectroscopy, is best fit to three exponentials. The fast phase is ligand dependent, while the two slower phases are ligand independent. The slower phases are similar but not identical in rate, and have opposite fluorescence amplitudes. Both isomers of mant-ATP are equivalent substrates, as judged by reversed-phase chromatography, although the rate of phosphorylation is approximately 20-fold lower than the natural nucleotide. The kinetic data are consistent with a three-step binding mechanism in which initial association of the nucleotide derivatives produces a highly fluorescent complex. Either one or two conformational changes can occur after the formation of this binary species, but one of the isomerized forms must have low fluorescence compared to the initial binary complex. These data soundly attest to the structural plasticity within the kinase core that may be essential for catalysis. Overall, the mant nucleotides present a useful reporter system for gauging these conformational changes in light of the prevailing three-dimensional models for the enzyme.

Opioid peptide receptor studies. 12. Buprenorphine is a potent and selective mu/kappa antagonist in the [35S]-GTP-gamma-S functional binding assay

We utilized the [(35)S]-GTP-gamma-S functional binding assay to determine the selectivity of opioid receptor agonists in guinea pig caudate membranes. The study focused on two opioid agonists used for treating opioid-dependent patients: methadone and buprenorphine. Selective antagonists were used to generate agonist-selective conditions: TIPP + nor-BNI to measure mu receptors, CTAP + nor-BNI to measure gamma receptors and TIPP + CTAP to measure kappa receptors. The assay was first validated with opioid agonists of known subtype specificity (DAMGO for mu, SNC80 for delta, and U69, 593 for kappa receptors). Methadone-stimulated [(35)S]-GTP-gamma-S binding was mu-specific and less potent and efficacious than etorphine (K(d) = 1,537 nM vs. K(d) = 7.8 nM). Buprenorphine failed to stimulate [(35)S]-GTP-gamma-S binding but inhibited agonist-stimulated [(35)S]-GTP-gamma-S binding. The antagonist-K(i) values (nM) of buprenorphine at mu, delta, and kappa receptors were 0.088 nM, 1.15 nM, and 0.072 nM, respectively. The antagonist-K(i) values (nM) of naloxone at mu, delta, and kappa receptors were 1.39 nM, 25.0 nM, and 11.4 nM, respectively. Autoradiographic studies showed that buprenorphine failed to stimulate [(35)S]-GTP-gamma-S binding in caudate-level rat brain sections but blocked DAMGO-stimulated [(35)S]-GTP-gamma-S binding. In cells expressing the cloned rat mu receptor, buprenorphine was a partial agonist and potent mu antagonist. Administration of buprenorphine to rats produced a long-lasting (>24 h) decrease in mu and kappa2 receptor binding and attenuated mu-stimulated [(35)S]-GTP-gamma-S binding. Viewed collectively, these data indicate that, in this assay system, buprenorphine is a potent mu and gamma receptor antagonist. The clinical implications remain to be elucidated. Synapse 34:83-94, 1999. Published 1999 Wiley-Liss, Inc.

Effects of heart position on the body-surface electrocardiogram

Previous studies have examined the influence of body position, respiration, and habitus on body surface potentials. However, the authors could only estimate the sources of the effects they documented. Among the proposed origin of changes in body surface potentials from those studies were the position of the heart, alterations in autonomic tone, differences in ventricular blood volume, and variations in torso resistivity. The goal of this study was to investigate specifically the role of geometric factors in altering body surface potentials and the electrocardiogram. For this, we used experiments with an isolated, perfused dog heart suspended in a realistically shaped electrolytic torso tank. The experimental preparation allowed us to measure epicardial and tank surface potentials simultaneously, and then reconstruct the geometry of both surfaces. Our results mimicked some of the features described by previous investigators. However, our results also showed differences that included considerably larger changes in the peak QRS and T-wave amplitudes with heart movement than those reported in human studies. We detected smaller values of root-mean-squared variability from heart movements than those reported in a human study comparing body surface potentials during change in inspiration and body position. There was better agreement with relative variability, which in these studies ranged from 0.11 to 0.42, agreeing well with an estimate from human studies of 0.40. Our results suggest that the isolated heart/torso tank preparation is a valuable tool for investigating the effects of geometric variation. Furthermore, the geometric position of the heart appears to be a large source of variation in body surface potentials. The size of these variations easily exceeded thresholds used to distinguish pathologic conditions and thus such variations could have important implications on the interpretation of the standard electrocardiogram.

Asymmetric synthesis of cyclopentanes bearing four contiguous stereocenters via an NHC-catalyzed Michael/Michael/esterification domino reaction

An NHC-catalyzed Michael/Michael/esterification domino reaction via homoenolate/enolate intermediates for the asymmetric synthesis of tetrasubstituted cyclopentanes bearing four contiguous stereocenters is described. A variety of α,β-unsaturated aldehydes and 2-nitroallylic acetates react well with good domino yields and high stereoselectivities.

NHC-Catalyzed Asymmetric Synthesis of Functionalized Succinimides from Enals and α-Ketoamides

The efficient asymmetric synthesis of highly substituted succinimides from α,β-unsaturated aldehydes and α-ketoamides via NHC-catalyzed [3+2] cycloaddition has been developed. The new scalable protocol significantly expands the utility of NHC catalysis for the synthesis of heterocycles and provides easy access to assemble a wide range of succinimides from simple starting materials.

NHC-catalyzed activation of α,β-unsaturated N-acyltriazoles: an easy access to dihydropyranones

Employing the NHC-catalyzed activation of α,β-unsaturated N-acyltriazoles an efficient enantioselective synthesis of dihydropyranones via a formal [3+3] cycloaddition with 1,3-dicarbonyl compounds is described.

Selective labeling of kappa 2 opioid receptors in rat brain by [125I]IOXY: interaction of opioid peptides and other drugs with multiple kappa 2a binding sites

Recent studies from our laboratory resolved two subtypes of the kappa 2 binding site, termed kappa 2a and kappa 2b, using guinea pig, rat, and human brain membranes depleted of mu and delta receptors by pretreatment with the site-directed acylating agents BIT (mu-selective) and FIT (delta-selective). 6 beta-Iodo-3,14-dihydroxy-17-cyclopropylmethyl-4,5 alpha-epoxymorphinan (IOXY), an opioid antagonist that has high affinity for kappa 2 sites, was radioiodinated to maximum specific activity (2200 Ci/mmol) and purified by high pressure liquid chromatography and used to characterize multiple kappa 2 binding sites. The results indicated that [125I]IOXY, like [3H]bremazocine, selectively labels kappa 2 binding sites in rat brain membranes pretreated with BIT and FIT. Using 100 nM [D-Ala2-MePhe4,Gly-ol5]enkephalin to block [125I]IOXY binding to the kappa 2b site, two subtypes of the kappa 2a binding site were resolved, both in the absence and presence of 50 microM 5'-guanylyimidodiphosphate. Viewed collectively, these results provide further evidence for heterogeneity of the kappa opioid receptor, which may provide new targets for drug design, synthesis, and therapeutics.

Preliminary ligand binding data for subtypes of the delta opioid receptor in rat brain membranes

Delta opioid binding sites were assayed using [3H][D-ala2,D-leu5]enkephalin and rat brain membranes depleted of mu binding sites with the site-directed acylating agent, 2-(p-ethoxybenzyl)-1-diethylaminoethyl-5-isothiocyanatobenzimid a zole-HCI. [D-Pen2,D-Pen5]enkephalin (DPDPE), [D-Pen2,L-Pen5]enkephalin, [D-Ala2]deltorphin-I and [D-Ala2]deltorphin-II inhibition curves were characterized by slope factors (Hill coefficients) less than 1. The low slope factor of DPDPE persisted in the presence of 50 microM 5'-guanylyimidodiphosphate in the assay Quantitative analysis of [D-ala2,D-leu5]enkephalin, DPDPE and [D-Ala2]deltorphin-I binding surfaces resolved two binding sites. Whereas [D-ala2,D-leu5]enkephalin had equal affinity for both sites, DPDPE and [D-Ala2]deltorphin-I had high affinity for the high capacity binding site, and low affinity for the low capacity binding site. These data support pharmacological studies demonstrating delta receptor subtypes which mediate antinociception.

High Expression of Human Leukocyte Antigen-G is Associated with a Poor Prognosis in Patients with PDAC

Pancreatic Adenocarcinoma (PDAC) is one of the most deadly malignant tumors worldwide. A variety of mechanisms are involved in PDAC biological behaviors, of which, the mechanisms of immune escape may be a pivotal hallmark. HLA-G is a tolerant molecule implicated in tumor escape and serves as a prognostic biomarker in tumors. Our study evaluated the expression of HLA-G in PDAC and explored its clinical significance. In a cohort of 122 PDAC patients, 78 patents (63.9%) exhibited high level of HLA-G tumor tissues. Multivariate analysis suggested that HLA-G level was an independent predictor for OS (HR = 3.894, 95% CI = 2.380-6.370, p <0.001). High level of HLA-G significantly correlated with PDAC aggressive features, such as more advanced stage (TNM Stage II) (p<0.001), extrapancreatic infiltration (T3 stage) (p<0.001), lymph node involvement (p=0.019) and poor differentiation (p=0.010). In western blot analysis, almost all of the tumor cell lines (5/6) expressed high levels of HLA-G. In ELISA analysis, the level of plasma sHLA-G in PDAC patients were significantly increased than in healthy control (P=0.0037). Further analysis revealed the level of sHLA-G inversely related to numbers of peripheral activated T cells (CD8+CD28+ T cells), which may indicate that sHLA-G inactivates T cell responses resulting in tumor immune escape. In conclusion, tumor-derived HLA-G may indicate the mechanism of immune escape and impaired PDAC clinical outcome, especially in early-stage patients, which may also be a potential therapeutic target.

Organocatalytic asymmetric [4+2] cyclization of 2-benzothiazolimines with azlactones: access to chiral benzothiazolopyrimidine derivatives

A squaramide catalyzed regiospecific and stereoselective [4+2] cyclization of 2-benzothiazolimines with azlactones has been established.

A novel interpolation method for electric potential fields in the heart during excitation

In mapping the electrical activity of the heart, interpolation of electric potentials plays two important roles. First, it permits the estimation of potentials in regions that could not be sampled or where signal quality was poor, and second, it supports the construction of isopotential lines and surfaces for visualization. The difficulty in developing robust interpolation techniques for cardiac applications lies in the abrupt change in potential in the vicinity of the activation wave front. Despite the resulting nonlinearities in spatial potential distributions, simple linear interpolation methods are the current standard and the resulting errors due to aliasing can be large if electrode spacing does not lie on the order of 0.5-2 mm--the thickness of the activation wave front. We have developed a novel interpolation method that is based on two observations specific to the spread of excitation in the heart: (1) that propagation velocity changes smoothly within a region large enough to contain several measurement electrodes and (2) that electrogram morphology varies very little in the neighborhood of each sample point except for a time shift in the potential wave forms. The resulting interpolation scheme breaks the interpolation of one highly nonlinear variable--extracellular potential--into two separate interpolations of variables with much less drastic spatial variation--activation time and electrogram morphology. We have applied this method to potentials originally recorded at 1.5 mm spacing and then subsampled at a range of densities for testing of the interpolation. The results based both on reconstruction of isopotential contour maps and statistical comparison showed significant improvement of this novel approach over standard linear techniques. The applications of the new method include improved determination of electrophysiological parameters such as spatial gradients of potential and the path of cardiac activation and recovery, estimation of electrograms at desired locations, and visualization of electric potential distributions.