			Home About us Contact

Precise Identity (precise + identity)

Distribution by Scientific Domains

Life Sciences	50%

Selected Abstracts

Haemoglobin Etobicoke, an incidental finding in an Irish diabetic

INTERNATIONAL JOURNAL OF LABORATORY HEMATOLOGY, Issue 4 2003
D. A. O'Brien
Summary It is well recognized that haemoglobin variants can be detected during the measurement of HbA1c by high-performance liquid chromatography (HPLC). A number of variants have been reported as compromising the quantification of HbA1c, a marker used in the assessment of glycaemic control in diabetes. We describe a case of haemoglobin Etobicoke, a rare alpha chain variant detected in an Irish diabetic during HbA1c analysis. Its identity was confirmed using a series of investigations. These included haemoglobin electrophoresis at alkaline and acid pH, isoelectric focusing and globin chain electrophoresis. Ultimately mass spectrometry isolated the mutation at position alpha 84 (F5). Haemoglobin Etobicoke, first described in Canada in 1969 has not previously been detected on HbA1c analysis. In the presence of this rare variant, HbA1c, a standard method using HPLC to assess glycaemic control in diabetes is unreliable and alternatives such as fructosamine need to be considered. HbA1c measured by automated HPLC will effectively screen populations where haemoglobin variants were not previously known. Precise identity of these variants when they are detected is crucial to the reliable interpretation of HbA1c analyses. [source]

Stably folded de novo proteins from a designed combinatorial library

PROTEIN SCIENCE, Issue 1 2003
Yinan Wei
Abstract Binary patterning of polar and nonpolar amino acids has been used as the key design feature for constructing large combinatorial libraries of de novo proteins. Each position in a binary patterned sequence is designed explicitly to be either polar or nonpolar; however, the precise identities of these amino acids are varied extensively. The combinatorial underpinnings of the "binary code" strategy preclude explicit design of particular side chains at specified positions. Therefore, packing interactions cannot be specified a priori. To assess whether the binary code strategy can nonetheless produce well-folded de novo proteins, we constructed a second-generation library based upon a new structural scaffold designed to fold into 102-residue four-helix bundles. Characterization of five proteins chosen arbitrarily from this new library revealed that (1) all are ,-helical and quite stable; (2) four of the five contain an abundance of tertiary interactions indicative of well-ordered structures; and (3) one protein forms a well-folded structure with native-like features. The proteins from this new 102-residue library are substantially more stable and dramatically more native-like than those from an earlier binary patterned library of 74-residue sequences. These findings demonstrate that chain length is a crucial determinant of structural order in libraries of de novo four-helix bundles. Moreover, these results show that the binary code strategy,if applied to an appropriately designed structural scaffold,can generate large collections of stably folded and/or native-like proteins. [source]

Differential galanin receptor-1 and galanin expression by 5-HT neurons in dorsal raphé nucleus of rat and mouse: evidence for species-dependent modulation of serotonin transmission

EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 3 2003
Jari A. Larm
Abstract Galanin and galanin receptors are widely expressed by neurons in rat brain that either synthesize/release and/or are responsive to, classical transmitters such as ,-aminobutyric acid, acetylcholine, noradrenaline, histamine, dopamine and serotonin (5-hydroxytryptamine, 5-HT). The dorsal raphé nucleus (DRN) contains , 50% of the 5-HT neurons in the rat brain and a high percentage of these cells coexpress galanin and are responsive to exogenous galanin in vitro. However, the precise identity of the galanin receptor(s) present on these 5-HT neurons has not been previously established. Thus, the current study used a polyclonal antibody for the galanin receptor-1 (GalR1) to examine the possible expression of this receptor within the DRN of the rat and for comparative purposes also in the mouse. In the rat, intense GalR1-immunoreactivity (IR) was detected in a substantial population of 5-HT-immunoreactive neurons in the DRN, with prominent receptor immunostaining associated with soma and proximal dendrites. GalR1-IR was also observed in many cells within the adjacent median raphé nucleus. In mouse DRN, neurons exhibited similar levels and distribution of 5-HT-IR to that in the rat, but GalR1-IR was undetectable. Consistent with this, galanin and GalR1 mRNA were also undetectable in mouse DRN by in situ hybridization histochemistry, despite the detection of GalR1 mRNA (and GalR1-IR) in adjacent cells in the periaqueductal grey and other midbrain areas. 5-HT neuron activity in the DRN is primarily regulated via 5-HT1A autoreceptors, via inhibition of adenylate cyclase and activation of inward-rectifying K+ channels. Notably, the GalR1 receptor subtype signals via identical mechanisms and our findings establish that galanin modulates 5-HT neuron activity in the DRN of the rat via GalR1 (auto)receptors. However, these studies also identify important species differences in the relationship between midbrain galanin and 5-HT systems, which should prompt further investigations in relation to comparative human neurochemistry and which have implications for studies of animal models of relevant neurological conditions such as stress, anxiety and depression. [source]

Potato yellow vein virus: its host range, distribution in South America and identification as a crinivirus transmitted by Trialeurodes vaporariorum

ANNALS OF APPLIED BIOLOGY, Issue 1 2000
L F SALAZAR
Summary Sporadic outbreaks of potato yellow vein disease (PYVD) were first observed in the early 1940's by potato growers in Antioquia, Colombia. Long known to be transmitted by the greenhouse whitefly (Trialeurodes vaporariorum), the precise identity of its causal agent (presumably viral in nature) has remained obscure. Here, we present evidence that a closterovirus with a bipartite genome, potato yellow vein virus (PYVV), is associated with PYVD. Electrophoretic analysis revealed that diseased tissue contains 4,5 disease-specific dsRNAs ranging in size from c. 9 000,1 800 bp. RT-PCR reactions containing pairs of degenerate primers directed against conserved motifs in the closterovirus heat-shock protein homologue produced products of the expected sizes. Comparison of the corresponding amino acid sequences revealed striking similarities between PYVV and two bipartite, whitefly-transmitted criniviruses, Cucurbit yellow stunting disorder and Tomato chlorosis viruses. Epidemiological surveys carried out in Rionegro, Colombia identified Polygonum mepalense, Polygonum spp., Rumex obtusifolium, Tagetes spp., and Catharanthus roseus as potential viral reservoirs. PYVV is transmitted through tubers, and visual symptoms alone cannot be used to determine infection status. A sensitive hybridisation-based assay for PYVV has been developed for use in seed certification programmes. [source]