Linearity of chromatographic systems in drug analysis part I: theory of nonlinearity and quantification of curvature.

Traditional approaches to the assessment of the linearity of chromatographic assays initially assume that the concentration-response relationship is linear and only deemed to be nonlinear if certain parameters lie outside pre-set acceptance criteria. A different approach is described in that the a priori assumption is made that the assay does have some curvature that can be described by fitting a nonlinear regression curve. Any nonlinearity can be quantified from the curvature terms of the resultant regression coefficients. The success of this alternative approach is dependent upon the appropriate choice of nonlinear regression to accurately describe concentration versus response relationship of the assay.

Linearity of chromatographic systems in drug analysis part II: a Monte Carlo justification for the use of nonlinear regressions.

In Part I of this series of communications an alternative approach was outlined to quantify the deviation from linearity by estimation of the change in true sensitivity of several mathematically defined concentration-response relationships. In this paper, Monte Carlo techniques were used to compare the strengths and limitations of linear and nonlinear regressions in assay calibrations. Nonlinear regressions can define a calibration curve as efficiently as a linear regression. Provided that the nonlinear regression is matched to the actual nonlinear concentration-response relationship, the use of nonlinear regressions can improve the accuracy of the assay and increase the percentage of calibrations meeting acceptance criteria.

Linearity of chromatographic systems in drug analysis part III: examples of nonlinear drug assays.

Chromatography-based drug assays are generally considered to be linear, provided that the back calculated concentrations of 75% of the calibrators are within ±15% of their target values. Data meeting this criterion are not usually subject to further examination in order to evaluate the extent of any nonlinearity and whether use of a nonlinear calibration function would improve the accuracy. Examples of nonlinear behavior are presented for several chromatographic systems and most are best described by the nonlinear equation y = a + bx + cxln(x). A more critical evaluation of linearity, as presented herein, can lead to the identification of nonlinear behavior and an improvement in accuracy by use of a nonlinear calibration regression.

Levels of Visual Stress in Proficient Readers: Effects of Spectral Filtering of Fluorescent Lighting on Reading Discomfort.

Visual stress (VS) affects reading in 5-12% of the general population and 31-36% of children with reading disorders. Symptoms include print distortions and visual discomfort when reading, and are exacerbated by fluorescent lighting. Prior research has indicated that VS can also affect proficient readers. We therefore examined levels of visual discomfort in a group of expert readers (n = 24) under both standard and spectrally-filtered fluorescent lighting. Participants rated their awareness of six symptoms of VS under each lighting condition. Under the standard condition, 4(16.7%) of the group recorded moderate to high levels of VS. Differences in symptom levels and reading speed between conditions were analysed using the Wilcoxon Signed Rank Test. Under the filter condition, the group reported less discomfort regarding all six symptoms of VS surveyed. The differences were significant with respect to three of the symptoms (p = .029 - p < .001), with a medium effect size in all of them (r = .31 - r = .46) and total score (p = .007; r = .39). Variations in reading proficiency included significantly fewer self-corrections (p = .019) and total errors (p = .004). Here we present evidence that VS-type symptoms of reading discomfort are not confined to populations with reading difficulties and may also occur in proficient readers, and that simple adaptations to fluorescent lighting may alleviate such symptoms.

The aneurysmal arteriovenous fistula - morphological study and assessment of clinical implications. A pilot study.

Aneurysmal dilation of arteriovenous fistulae used for haemodialysis is a recognised complication but its clinical significance is a contentious issue. Our aims were to describe aneurysmal fistulae morphologically and clinically.Sixty patients underwent duplex scanning to measure the maximum diameter and skin thickness of their fistula. Haemodialysis function and bleeding risk were assessed clinically.The 75th percentile of maximum diameter was 2.05 cm. In addition to conventional diameter measurement, we describe a novel volume measurement technique which may be of value. No relationship was found between maximum diameter or volume and function, skin thickness or bleeding.Some studies define aneurysm at 2 cm (75th percentile); however, this definition and other arbitrary definitions lack clinical significance. This work suggests that fistula dilation should be considered together with clinical issues when determining the clinical significance of an aneurysm. Our finding that haemodialysis function, skin thickness and bleeding were not associated with diameter needs further study.

Levels of visual stress in proficient readers: effects of spectral filtering of fluorescent lighting on reading discomfort

Visual stress (VS) affects reading in 5-12% of the general population and 31-36% of children with reading disorders. Symptoms include print distortions and visual discomfort when reading, and are exacerbated by fluorescent lighting. Prior research has indicated that VS can also affect proficient readers. We therefore examined levels of visual discomfort in a group of expert readers (n = 24) under both standard and spectrally-filtered fluorescent lighting. Participants rated their awareness of six symptoms of VS under each lighting condition. Under the standard condition, 4(16.7%) of the group recorded moderate to high levels of VS. Differences in symptom levels and reading speed between conditions were analysed using the Wilcoxon Signed Rank Test. Under the filter condition, the group reported less discomfort regarding all six symptoms of VS surveyed. The differences were significant with respect to three of the symptoms (p = .029 - p < .001), with a medium effect size in all of them (r = .31 - r = .46) and total score (p = .007; r = .39). Variations in reading proficiency included significantly fewer self-corrections (p = .019) and total errors (p = .004). Here we present evidence that VS-type symptoms of reading discomfort are not confined to populations with reading difficulties and may also occur in proficient readers, and that simple adaptations to fluorescent lighting may alleviate such symptoms (AU)

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Taking the learning beyond the individual: how reflection informs change in practice.

OBJECTIVE: The purpose of this research was to explore the value of reflection and its application to practice through the implementation of educational modules within a new Diabetes Care and Education Master Degree Programme in Kuwait, and to realise how this teaching intervention informs changes in practice. METHODS: A small exploratory case study was conducted within the Dasman Diabetes Institute, Kuwait. A qualitative approach using focus group interviews was carried out with seventeen participants all of whom are studying on the Diabetes Care and Education Master Degree Programme in Kuwait. An inductive approach to thematic analysis, which focused on examining themes within data, was performed. RESULTS: The results indicate that participants value the opportunity to study through organised, structured and assessed reflection. The learning provides useful information and support to the participant by highlighting the role which reflection plays to enhance personal and professional development, the value of educational theory, continuing professional development, collaboration and enhancing patient education and practice. CONCLUSIONS: The significance of reflection is often seen in the literature as an important aspect of professional competence. This research has highlighted the value of reflection as a key component within a new educational programme.

Electrospray ionization-tandem mass spectrometry analysis of phospholipid molecular species from Antarctic and non-Antarctic yeasts.

High performance liquid chromatography-electrospray ionization tandem mass spectrometry was applied to the comprehensive analysis of phospholipids from seven Antarctic and seven non-Antarctic yeasts. Identification of specific fatty acyl moieties to the sn-1 and sn-2 positions of phosphatidylethanolamine (PE), phosphatidylcholine (PC), phosphatidylserine (PS) and phosphatidylinositol (PI) were determined by relative abundance of fragment ions associated with formation of carboxylate anions and loss of fragment ions as free fatty carboxylic acid and ketene. Modulations with growth temperature in fatty acyl moieties in the sn-1 and sn-2 positions were characterized. Principal component analysis demonstrated that PE, PC and to a lesser extent PS, but not PI, were grouped into three distinct clusters consisting of seven Antarctic yeasts (Cryptococcus victoriae, Holtermanniella wattica, H. nyarrowii, Candida psychrophila, Leucosporidium fellii, Glaciozyma antarctica, Rhodotorula mucilaginosa), four non-Antarctic yeasts (C. albicans, Zygosaccharomyces rouxii, Cr. humicolus, R. mucilaginosa) and three strains of Saccharomyces cerevisiae.

Gas chromatography-mass spectrometry analysis of fatty acid profiles of Antarctic and non-Antarctic yeasts.

The fatty acid profiles of Antarctic (n = 7) and non-Antarctic yeasts (n = 7) grown at different temperatures were analysed by gas chromatography-mass spectrometry. The Antarctic yeasts were enriched in oleic 18:1 (20-60 %), linoleic 18:2 (20-50 %) and linolenic 18:3 (5-40 %) acids with lesser amounts of palmitic 16:0 (<15 %) and palmitoleic 16:1 (<10 %) acids. The non-Antarctic yeasts (n = 4) were enriched in 18:1 (20-55 %, with R. mucilaginosa at 75-80 %) and 18:2 (10-40 %) with lesser amounts of 16:0 (<20 %), 16:1 (<20 %) and stearic 18:0 (<10 %) acids. By contrast, Saccharomyces cerevisiae strains (n = 3) were enriched in 16:1 (30-50 %) and 18:1 (20-40 %) with lesser amounts of 16:0 (10-25 %) and 18:0 (5-10 %) acids. Principal component analysis grouped the yeasts into three clusters, one belonging to the S. cerevisiae strains (enriched in 16:0, 16:1 and 18:1), one to the other non-Antarctic yeasts (enriched in 18:1 and 18:2) and the third to the Antarctic yeasts (enriched in 18:2 and 18:3).

Imaging manifestations of mediastinal fat necrosis.

Mediastinal fat necrosis (MFN) or epipericardial fat necrosis, as it is commonly referred to in the literature, is a rare self-limiting cause of chest pain of unclear etiology. MFN affects previously healthy individuals who present with acute pleuritic chest pain. Characteristic computed tomography (CT) findings include a fat attenuation lesion with intrinsic and surrounding increased attenuation stranding. There is often associated thickening of the adjacent pericardium and/or pleural effusions. We present two cases of MFN manifesting as ovoid fat attenuation lesions demarcated by a soft tissue attenuation rim with intrinsic and surrounding soft tissue attenuation stranding and review the clinical and pathologic features of these lesions. Knowledge of the clinical presentation of patients with MFN and familiarity with the characteristic imaging findings of these lesions should allow radiologists to prospectively establish the correct diagnosis and suggest conservative management and follow-up.

Determination and differentiation of triacylglycerol molecular species in Antarctic and non-Antarctic yeasts by atmospheric pressure-chemical ionization-mass spectrometry.

Yeast, particularly Saccharomyces cerevisiae, has long served as a model eukaryotic system for studies on the regulation of lipid metabolism. We developed a high performance liquid chromatography-atmospheric pressure chemical ionization-mass spectrometry method for the detailed analysis of triacylglycerols (TAGs) in 14 species of yeast consisting of seven Antarctic yeasts (grown at 15°C and 5°C) and seven non-Antarctic yeasts (grown at 25°C and 15°C), the latter including 3 strains of S. cerevisiae. Analysis of TAG molecular species established that the sn-2 position was invariably occupied by an unsaturated fatty acyl moiety. In S. cerevisiae the preference was for oleic acid 18:1>palmitoleic acid 16:1, in Candida albicans, Cryptococcus humicolus and Rhodotorula mucilaginosa 18:1>linoleic acid 18:2 and in Zygosaccharomyces rouxii 18:2>18:1. In the Antarctic yeasts (Cryptococcus watticus, Cryptococcus victoriae, Cryptococcus nyarrowii, Leucosporidium antarcticum, Leucosporidium fellii, Candida psychrophila and Rhodotorula mucilaginosa) the general pattern was for the sn-2 position to be occupied by 18:1, 18:2 or linolenic acid 18:3. A trend towards synthesis of increased unsaturated fatty acid in TAGs was observed as the growth temperature was lowered. The application of principal component analysis demonstrated that the yeasts were differentiated into three distinct groups. One group consisted of the three S. cerevisiae strains, a second the other four non-Antarctic yeasts and the third the seven Antarctic yeasts. The data for the Antarctic yeasts, to the best of our knowledge, have not been previously reported.

Chemical and biological characterization of novel essential oils from Eremophila bignoniiflora (F. Muell) (Myoporaceae): a traditional Aboriginal Australian bush medicine.

Essential oils were extracted by hydrodistillation from the traditional Australian medicinal plant Eremophila bignoniiflora, characterized chemically and then screened for bioactivity. Characterization and quantification were completed using gas chromatography-mass spectrometry (GC-MS) and GC-flame ionization detection, respectively. Antimicrobial capacity was assessed using disc diffusion and micro-titre plate broth dilution and further characterized using thin layer chromatography followed by bioautography to assign activity to separated individual active components. Antifungal capacity was investigated using micro-titre plate broth dilution against pathogenic Trichophyton species. Free radical scavenging ability was assessed using the diphenylpicrylhydradyl reaction in methanol. The predominant components of the essential oil were fenchyl-acetate and bornyl-acetate. However, bioautography indicated antimicrobial ability to be largely linked to the less abundant, more polar constituents. Oils displayed only modest antifungal ability against pathogenic Trichophyton species associated with dermatophytosis, but moderate to high antimicrobial activity, particularly against the yeast Candida albicans and the bacteria Staphylococcus epidermidis. Essential oils exhibited relatively low free radical scavenging ability. Speculation over the role of essential oils in the traditional medicinal applications of E. bignoniiflora follows, exploring correlations between traditional use and investigated bioactivities.

A prospective genetic marker of the visual-perception disorder Meares-Irlen syndrome.

Prior investigations of scotopic sensitivity or Meares-Irlen syndrome have identified several features also found in attention deficit/hyperactivity disorder, chronic fatigue syndrome, and a subtype of dyslexia in which visual recognition is the primary deficit. In particular, anomalies in lipid metabolism, including low essential fatty acid status and decreased serum cholesterol, have been identified in all three disorders. Genetic expression of the transportermolecule apolipoprotein B-100 (APOB) has been correlated with abnormal lipid metabolism, particularly in relation to levels of cholesterol. Cholesterol esters are important carriers of essential fatty acids entering the retina. The APOB gene coding for apolipoprotein B-100 is located on the short arm of Chromosome 2, and closely neighbours a gene (DYX3) known to confer susceptibility to dyslexia. The APOB locus is also recognised as being one of the most highly polymorphic regions of the human genome, and thus provides a promising tool for genetic researchers. In this pilot study, certain allelic variants of the APOB gene were more common in participants diagnosed with Meares-Irlen syndrome than in individuals without the condition. This study appears to be a first in which a condition known to cause reading difficulties has been associated with the APOB gene.

Glioblastoma. Part II: Future directions.

Although uncommon, "brain cancer" is one of the most feared diseases that afflict human beings. While still regarded as one of the most deadly forms of primary malignant brain neoplasm, recent advances in the treatment of Glioblastoma Multiforme (GBM) have offered new hope for patients, families and clinicians. In the first part of this two-part evidence-based review, we focused on the multidisciplinary advances that have established the current standard of care practice in the management of GBM. The second part discusses ongoing research efforts, both ongoing clinical trial efforts as well as some of the newer technologies that are forming the promise of the future.

Glioblastoma: Part I. Current state of affairs.

Although uncommon, "brain cancer" is one of the most feared diseases that afflict human beings. While still regarded as one of the most deadly forms of primary brain neoplasm, recent advances in the treatment of glioblastoma (GBM) have offered new hope for patients, families, and clinicians. In the first part of this two-part review, we will focus on the multidisciplinary advances that have established the current treatment approach in the management of GBM. In the second part of this review, ongoing research will be presented including current clinical trials as well as some of the newer technologies that are forming the promise of the future.

Associations of HSP90 client proteins in human breast cancer.

BACKGROUND: HSP90 has been studied intensively as a therapeutic target, however little is known regarding specific interactions of the large number of HSP90 client proteins. Therefore, this study investigated HSP90 client proteins sensitive to the HSP90 inhibitor geldanamycin in tumour and healthy breast tissue. MATERIALS AND METHODS: Co-immunoprecipitation and SDS-PAGE were used to investigate protein interactions. Western blotting and LC-MS were used to infer protein identities. RESULTS: HSP90 client proteins were observed in 7 out of 11 breast cancer patients. Further experiments inferred HSP40, -56/FKBP52, -60, -70, -105 and lumican to associate with HSP90 and to belong to this group of geldanamycin-sensitive proteins. In one patient, a cancer-specific group of proteins was identified. In all experiments geldanamycin resistance was observed. CONCLUSION: HSP90 differentially associated with client proteins and this was patient dependent. Geldanamycin resistance and lack of HSP90 client protein expression may limit clinical applications of HSP90 inhibitors.

Intraspecific variation in essential oil composition of Eremophila longifolia F. Muell. (Myoporaceae): evidence for three chemotypes.

Volatile oils of Eremophila longifolia F. Muell. (Myoporaceae) leaves were obtained by hydrodistillation and analysed using GC-MS. A total of 33 compounds were identified in the oils examined and a high degree of intraspecific variability in chemical composition between specimens occurring in separate geographic localities was found. Multivariate statistical analysis of chemical composition of volatile oils enabled classification of three chemotypes in this species.

Cold-adapted yeasts from Antarctica and the Italian Alps-description of three novel species: Mrakia robertii sp. nov., Mrakia blollopis sp. nov. and Mrakiella niccombsii sp. nov.

Worldwide glaciers are annually retreating due to global overheating and this phenomenon determines the potential lost of microbial diversity represented by psychrophilic microbial population sharing these peculiar habitats. In this context, yeast strains, all unable to grow above 20 degrees C, consisting of 42 strains from Antarctic soil and 14 strains isolated from Alpine Glacier, were isolated and grouped together based on similar morphological and physiological characteristics. Sequences of the D1/D2 and ITS regions of the ribosomal DNA confirmed the previous analyses and demonstrated that the strains belong to unknown species. Three new species are proposed: Mrakia robertii sp. nov. (type strain CBS 8912), Mrakia blollopis sp. nov. (type strain CBS 8921) and a related anamorphic species Mrakiella niccombsii sp. nov. (type strain CBS 8917). Phylogenetic analysis of the ITS region revealed that the new proposed species were closely related to each other within the Mrakia clade in the order Cystofilobasidiales, class Tremellomycetes. The Mrakia clade now contains 8 sub-clades. Teliospores were observed in all strains except CBS 8918 and for the Mrakiella niccombsii strains.

Identification of antibacterial constituents from the indigenous Australian medicinal plant Eremophila duttonii F. Muell. (Myoporaceae).

This paper reports on the isolation and identification of antibacterial constituents from the indigenous Australian medicinal plant Eremophila duttonii F. Muell. (Myoporaceae). Preparations derived from this plant are used by indigenous populations in the topical treatment of minor wounds, otitis and ocular complaints, and as a gargle for sore throat. Several authors have reported extracts of this plant to effect rapid bacteriolysis and inhibit growth of a wide range of Gram-positive micro-organisms. In other studies involving screening of native medicinal plants for antibacterial activity, extracts of Eremophila duttonii have been reported to consistently exhibit the highest potency amongst all species included. From a hexane extract, we identified two diterpenes of the serrulatane class, the principal constituents responsible for antibacterial activity and present as major constituents of the resinous leaf cuticle: serrulat-14-en-7,8,20-triol (1) and serrulat-14-en-3,7,8,20-tetraol (2). In addition, a hydroxylated furanosesquiterpene with mild antibacterial activity which appeared to be a novel compound was isolated from the extract and tentatively identified as 4-hydroxy-4-methyl-1-(2,3,4,5-tetrahydro-5-methyl[2,3'-bifuran]-5-yl) pentan-2-one. Minimum inhibitory concentrations for each of the compounds against three Gram-positive bacteria: Staphylococcus aureus (ATCC 29213), Staphylococcus epidermidis (ATCC 12228) and Streptococcus pneumoniae (ARL 10582), were determined using a micro-titre plate broth dilution assay.