Global mass spectrometry based metabolomics profiling of erythrocytes infected with Plasmodium falciparum

Malaria is a global infectious disease that threatens the lives of millions of people. Transcriptomics, proteomics and functional genomics studies, as well as sequencing of the Plasmodium falciparum and Homo sapiens genomes, have shed new light on this host-parasite relationship. Recent advances in accurate mass measurement mass spectrometry, sophisticated data analysis software, and availability of biological pathway databases, have converged to facilitate our global, untargeted biochemical profiling study of in vitro P. falciparum-infected (IRBC) and uninfected (NRBC) erythrocytes. In order to expand the number of detectable metabolites, several key analytical steps in our workflows were optimized. Untargeted and targeted data mining resulted in detection of over one thousand features or chemical entities. Untargeted features were annotated via matching to the METLIN metabolite database. For targeted data mining, we queried the data using a compound database derived from a metabolic reconstruction of the P. falciparum genome. In total, over one hundred and fifty differential annotated metabolites were observed. To corroborate the representation of known biochemical pathways from our data, an inferential pathway analysis strategy was used to map annotated metabolites onto the BioCyc pathway collection. This hypothesis-generating approach resulted in over-representation of many metabolites onto several IRBC pathways, most prominently glycolysis. In addition, components of the “branched” TCA cycle, partial urea cycle, and nucleotide, amino acid, chorismate, sphingolipid and fatty acid metabolism were found to be altered in IRBCs. Interestingly, we detected and confirmed elevated levels for cyclic ADP ribose and phosphoribosyl AMP in IRBCs, a novel observation. These metabolites may play a role in regulating the release of intracellular Ca²⁺ during P. falciparum infection. Our results support a strategy of global metabolite profiling by untargeted data acquisition. Untargeted and targeted data mining workflows, when used together to perform pathway-inferred metabolomics, have the benefit of obviating MS/MS confirmation for every detected compound.

Attitudes in the management of patients with dementia: comparison in doctors with and without special training

OBJECTIVE

To explore by postal survey the different attitudes towards management of patients with dementia in physicians with and without dementia training.

METHODS

A questionnaire was sent to 7669 members of the Hong Kong Medical Association, which represents 61% of all locally registered medical practitioners.

RESULTS

In all, 448 questionnaires were returned (response rate: 6%). Among these, there were 34 questionnaires with missing data or the respondents indicated that they were either retired or not in practice. Therefore, only 414 questionnaires were used in analysis. Among these, 82 (20%) had received dementia training, 310 (75%) had not, and 22 (5%) did not indicate their choice. Twelve statements were used to explore various attitudes about dementia care. Exploratory factor analysis showed that there were 2 strong factors: confidence and negative views. The mean scores of these 2 factors were significantly different in physicians with and without dementia training. With respect to management of patients with dementia, dementia-trained physicians had significantly greater confidence (mean [standard deviation (SD)] = 5.21 [1.34]) than those who were non-trained (mean [SD] = 3.57 [1.40]; p < 0.001). Conversely, non-trained physicians had significantly stronger negative views (mean [SD] = 3.89 [1.24]) on dementia care than those who were trained (mean [SD] = 3.12 [1.36]; p < 0.001).

DISCUSSION

These findings suggest that providing a certain level of dementia care training for physicians is an effective way to improve confidence in managing patients with dementia, and thereby decrease possible negative attitudes towards such care.

Low values of left ventricular ejection time in the post-anhepatic phase may be associated with occurrence of primary graft dysfunction after orthotopic liver transplantation: results of a single-centre case-control study

BACKGROUND

Previous investigations on risk factors for orthotopic liver transplantation (OLT) surgery have not analyzed hemodynamic aberrations in great detail. Moreover, the usefulness of esophageal Doppler monitoring has not been extensively studied in this clinical setting. The aim of this study was to evaluate if the occurrence of primary graft dysfunction (PGD) may be anticipated by hemodynamic indexes measured by esophageal Doppler (ED) monitoring system as well as by pulmonary artery catheter (PAC) in patients undergoing OLT.

MATERIALS AND METHODS

38 OLT recipients were studied. Patients with acute liver failure or having non treated esophageal varices and those transplanted with marginal donors were excluded from the study. The haemodynamic data - measured by ED monitoring system (HemosonicTM 100, Arrow, OK, USA) and PAC - collected at the following 3 time points were considered for statistical analysis: 30 minutes after the induction of anesthesia but before skin incision, T0; 20 minutes after liver dissection, T1; at the beginning of biliary reconstruction, T2. On the basis of early outcome (72 hours after OLT), patients were distinguished into two groups: those with PGD (grade III-IV of Toronto classification) and those without PGD (grade I-II).

RESULTS

LVETc (left ventricular ejection time) values, registered at the beginning of biliary reconstruction (T2), were lower in patients with PGD compared to those without PGD (p < 0.000), while there were no differences in hemodynamic parameters derived from PAC between the two groups.

CONCLUSIONS

Since LVETc is related to preload, the results of this study would suggest that normovolemia could be the end point of a fluid replacement strategy in OLT setting.

High incidence of skin cancer in the Channel Islands

BACKGROUND

Previous studies looking at rates of malignant melanoma (MM) and nonmelanoma skin cancer (NMSC) in the UK have documented one of the highest rates in the southwest of England; however, the incidence of these tumours in Guernsey and Jersey, two of the Channel Islands, has not previously been reported.

AIMS

To determine the incidence of cutaneous MM and NMSC in the Channel Islands.

METHODS

Data for the period 2005-2009 were obtained from clinical and histopathological records for all MMs excised in the Channel Islands, and from the South-west Cancer Registry for MMs excised in the southwest of England and for NMSCs in both areas. The age-standardized incidence rate (ASRs) per 100,000 of the population in the Channel Islands were compared with those with the southwest of England, the UK and the rest of Europe where available. The MM characteristics of the Channel Islands were then compared with the southwest of England using standardized incidence ratios (SIRs).

RESULTS

The ASR/100,000 for cutaneous MM for 2005-2009 was 30 for the Channel Islands (31.3 for Jersey, 28.2 for Guernsey), 20.3 for the southwest of England, and 15.6 for the UK. Comparison with the rest of Europe indicated that the incidence of MM in the Channel Islands is one of the highest in Europe. The highest incidence of MM was in the over 65 years age group on both Guernsey and Jersey, and when divided into 5-year age bands, the 70-74 years age group had the highest rate. This suggests that this particular age group may have previously received greater exposure to some environmental factor that promotes MM development. The ASR/100,000 for NMSC was also higher for the Channel Islands (263.3) than for the southwest of England (174.6) for 2005-2009, and for the UK in 2009 (104.9).

CONCLUSIONS

This study indicates that the Channel Islands have a high incidence of skin cancer (both MM and NMSC). In addition, the data show that the ASRs in older people in this population group differ from those in mainland UK, showing higher rates in the over 65 years age group.

A comparison of two methods of teaching reflective ability in Year 3 medical students

CONTEXT

Little is known about best practices for teaching and learning reflection. We hypothesised that reflective ability scores on written reflections would be higher in students using critical reflection guidelines, or receiving feedback on reflective skill in addition to reflection content, or both, compared with those in students who received only a definition of reflection or feedback on reflection content alone.

METHODS

Using a 2 (guidelines) × 2 (feedback) × 2 (time) design, we randomly assigned half of our sample of 149 Year 3 medical students to receive critical reflection guidelines and the other half to receive only a definition of critical reflection. We then randomly divided both groups in half again so that one half of each group received feedback on both the content and reflective ability in their reflections, and the other received content feedback alone. The learners' performance was measured on the first and third written reflections of the academic year using a previously validated scoring rubric. We calculated descriptive statistics for the reflection scores and conducted a repeated-measures analysis of variance with two between-groups factors, guidelines and feedback, and one within-group factor, occasion, using the measure of reflective ability as the dependent variable.

RESULTS

We failed to find a significant interaction between guidelines and feedback (F = 0.51, d.f. = 1, 145, p = 0.48). However, the provision of critical reflection guidelines improved reflective ability compared with the provision of a definition of critical reflection only (F = 147.1, d.f. = 1, 145, p < 0.001). Feedback also improved reflective ability, but only when it covered reflective skill in addition to content (F = 6.5, d.f. = 1, 145, p = 0.012).

CONCLUSIONS

We found that the provision of critical reflection guidelines improved performance and that feedback on both content and reflective ability also improved performance. Our study demonstrates that teaching learners the characteristics of deeper, more effective reflection and helping them to acquire the skills they need to reflect well improves their reflective ability as measured by performance on reflective exercises.

MAT1A variants modulate the effect of dietary fatty acids on plasma homocysteine concentrations

BACKGROUND AND AIM

Dietary n-3 polyunsaturated fatty acids (PUFAs) are associated with decreased plasma homocysteine (Hcy), an important biomarker for cardiovascular disease. The S-adenosylmethionine synthetase type-1 (MAT1A), an essential enzyme in the conversion of methionine to S-adenosylmethionine, plays a key role in homocysteine metabolism. This study investigated the interaction between dietary fatty acids and MAT1A genotypes on plasma Hcy concentrations among Boston Puerto Ricans.

METHODS AND RESULTS

Plasma Hcy and MAT1A genotypes were determined in 994 subjects of the Boston Puerto Rican Health Study. Dietary fatty acid intakes were assessed by interviews using a questionnaire adapted from the NCI/Block food frequency form.

RESULT

In the cross-sectional analysis, genetic variant MAT1A 3U1510 displayed a significant interaction with dietary n-3:n-6 PUFA ratio in determining plasma Hcy (p-value for interaction = 0.025). 3U1510G homozygotes had significantly lower plasma Hcy concentration than major allele homozygotes and heterozygotes (AA + AG) (p-value for trend = 0.019) when the n-3:n-6 ratio was >0.09. Two other MAT1A variants, d18777 and i15752, also showed significant interactions with different constituents of dietary fat influencing Hcy concentrations. Furthermore, haplotypes consisting of three variants displayed a strong interaction with n3:n6 ratio influencing Hcy concentrations.

CONCLUSIONS

Our results suggest that MAT1A genotypes appear to modulate effects of dietary fat on plasma Hcy.

Assessing fibromyalgia-related fatigue: content validity and psychometric performance of the Fatigue Visual Analog Scale in adult patients with fibromyalgia

OBJECTIVES

To document 1) the content validity and 2) measure improvements in fatigue, using the Fatigue Visual Analogue Scale (VAS) assessment tool in patients with fibromyalgia.

METHODS

The relevance and comprehensiveness of the Fatigue VAS were tested through a qualitative analysis of 20 subjects' verbatim transcripts from semi-structured qualitative interviews. Data from two randomised, controller trials in fibromyalgia (n=1121) were used to conduct correlation analyses with the Fatigue and Tiredness items from the Fibromyalgia Impact Questionnaire (FIQ) and the Short Form-36 Vitality scale. Known-groups and cross classification analyses were conducted to demonstrate the ability to measure improvement in fatigue using the Fatigue VAS.

RESULTS

All subjects spontaneously reported that fatigue was an important symptom to capture in fibromyalgia. The Fatigue VAS was well understood by most subjects (n=18/20). High correlations (Pearson r>0.75) and good agreement (k>0.66) were found between the Fatigue VAS and the FIQ tiredness items no. 16 and 17 and SF-36™ Vitality scale. In both clinical trials there was a substantial separation of approximately 20 points on the mean change in the Fatigue VAS score between responders (>30% improvement in pain VAS) and non-responders.

CONCLUSIONS

Previous studies have confirmed that fatigue is a major component of the fibromyalgia experience. This current study reports that fibromyalgia patients spontaneously rated fatigue as a highly significant feature of their illness, and supports the use of the Fatigue VAS as a valid questionnaire in fibromyalgia clinical trials.