Multi-centre reproducibility of diffusion MRI parameters for clinical sequences in the brain.

The purpose of this work was to assess the reproducibility of diffusion imaging, and in particular the apparent diffusion coefficient (ADC), intra-voxel incoherent motion (IVIM) parameters and diffusion tensor imaging (DTI) parameters, across multiple centres using clinically available protocols with limited harmonization between sequences. An ice-water phantom and nine healthy volunteers were scanned across fives centres on eight scanners (four Siemens 1.5T, four Philips 3T). The mean ADC, IVIM parameters (diffusion coefficient D and perfusion fraction f) and DTI parameters (mean diffusivity MD and fractional anisotropy FA), were measured in grey matter, white matter and specific brain sub-regions. A mixed effect model was used to measure the intra- and inter-scanner coefficient of variation (CV) for each of the five parameters. ADC, D, MD and FA had a good intra- and inter-scanner reproducibility in both grey and white matter, with a CV ranging between 1% and 7.4%; mean 2.6%. Other brain regions also showed high levels of reproducibility except for small structures such as the choroid plexus. The IVIM parameter f had a higher intra-scanner CV of 8.4% and inter-scanner CV of 24.8%. No major difference in the inter-scanner CV for ADC, D, MD and FA was observed when analysing the 1.5T and 3T scanners separately. ADC, D, MD and FA all showed good intra-scanner reproducibility, with the inter-scanner reproducibility being comparable or faring slightly worse, suggesting that using data from multiple scanners does not have an adverse effect compared with using data from the same scanner. The IVIM parameter f had a poorer inter-scanner CV when scanners of different field strengths were combined, and the parameter was also affected by the scan acquisition resolution. This study shows that the majority of diffusion MRI derived parameters are robust across 1.5T and 3T scanners and suitable for use in multi-centre clinical studies and trials

LeukoCatch, a quick and efficient tool for the preparation of leukocyte extracts from blood

<p>Abstract</p> <p>Background</p> <p>Whole-protein extracts from peripheral blood leukocytes are ideal for basic and clinical research. However, lack of a simple preparation technique has limited the use of such extracts. The aim of this study is to develop a simple and easy system that can selectively obtain leukocyte extracts without hemoglobin.</p> <p>Methods</p> <p>A filter that captures the leukocytes but not RBCs was set at the bottom of a 10-mL medical syringe by sandwiching it between plastic stoppers. The capturing efficiency of leukocytes with this tool, called LeukoCatch, was examined using human macrophage cells (MONO-MAC-6). The abilities of LeukoCatch system to capture the leukocyte proteins and to remove the hemoglobin from RBCs were tested by western blot analysis using human blood samples.</p> <p>Results</p> <p>This study presents the development of LeukoCatch, a novel tool that allows the preparation of leukocyte extracts from blood samples within 3 min without centrifugation. Tissue-cultured human macrophage cells were tested to determine the optimal filter numbers and pass-through frequencies of LeukoCatch, which was then applied to 2-mL blood samples. Samples were passed 2~5 times through a LeukoCatch equipped with 5 filters, washed twice with phosphate-buffered saline for red cell removal, and leukocyte proteins were extracted with 0.5 mL of elution buffer. Western blot analysis of the purified extract indicated that more than 90% of hemoglobin was removed by the LeukoCatch and that the protein recovery rate of leukocytes was at least 4 times better than that of the conventional centrifugation method.</p> <p>Conclusion</p> <p>We conclude that LeukoCatch is useful not only for diagnosis at the bedside but also for basic research using blood samples or tissue culture cells.</p

From L-Dopa to Dihydroxyphenylacetaldehyde: A Toxic Biochemical Pathway Plays a Vital Physiological Function in Insects

One protein in Aedes aegypti, classified into the aromatic amino acid decarboxylase (AAAD) family based on extremely high sequence homology (∼70%) with dopa decarboxylase (Ddc), was biochemically investigated. Our data revealed that this predicted AAAD protein use L-dopa as a substrate, as does Ddc, but it catalyzes the production of 3,4-dihydroxylphenylacetaldehyde (DHPAA) directly from L-dopa and apparently has nothing to do with the production of any aromatic amine. The protein is therefore named DHPAA synthase. This subsequently led to the identification of the same enzyme in Drosophila melanogaster, Anopheles gambiae and Culex quinquefasciatus by an initial prediction of putative DHPAA synthase based on sequence homology and subsequent verification of DHPAA synthase identity through protein expression and activity assays. DHPAA is highly toxic because its aldehyde group readily reacts with the primary amino groups of proteins, leading to protein crosslinking and inactivation. It has previously been demonstrated by several research groups that Drosophila DHPAA synthase was expressed in tissues that produce cuticle materials and apparent defects in regions of colorless, flexible cuticular structures have been observed in its gene mutants. The presence of free amino groups in proteins, the high reactivity of DHPAA with the free amino groups, and the genetically ascertained function of the Drosophila DHPAA synthase in the formation of colorless, flexible cuticle, when taken together, suggest that mosquito and Drosophila DHPAA synthases are involved in the formation of flexible cuticle through their reactive DHPAA-mediated protein crosslinking reactions. Our data illustrate how a seemingly highly toxic pathway can serve for an important physiological function in insects

Identification of Essential Sequences for Cellular Localization in BRMS1 Metastasis Suppressor

10 páginas, 5 figuras. PMID: 19649328 [PubMed] PMCID: PMC2713406BACKGROUND: Breast cancer metastasis suppressor 1 (BRMS1) reduces the number and the size of secondary tumours in a mouse model without affecting the growth of the primary foci upon its re-expression. Knockdown of BRMS1 expression associates with metastasis. The molecular details on BRMS1 mechanism of action include its ability to function as a transcriptional co-repressor and consistently BRMS1 has been described as a predominantly nuclear protein. Since cellular distribution could represent a potential mechanism of regulation, we wanted to characterize BRMS1 sequence motifs that might regulate its cellular distribution. According to its amino acids sequence, BRMS1 contain two putative nuclear localization signals, however none of them has been proved to work so far. METHODOLOGY/PRINCIPAL FINDINGS: By using well known in vivo assays to detect both nuclear import and export signal, we have characterized, in the present study, one functional nuclear localisation signal as necessary and sufficient to promote nuclear transport. Additionally, the outcome of a directed yeast two-hybrid assay identify importin alpha6 as a specific partner of BRMS1 thus speculating that BRMS1 nuclear import could be specifically mediated by the reported nuclear transporter. Besides, the combination of a computational searching approach along the utilization of a nuclear export assay, identified a functional motif within the BRMS1 sequence responsible for its nuclear export, that resulted not affected by the highly specific CRM1 inhibitor Leptomycin-B. Interspecies heterokaryon assay demonstrate the capability of BRMS1 to shuttle between the nuclear and cytosolic compartments CONCLUSIONS/SIGNIFICANCE: Our results show for the first time that BRMS1 contains both nuclear import and export signals enabling its nucleo-cytoplasmic shuttling. These findings contributes new data for the understanding of the BRMS1 functions and allow us to speculate that this phenomenon could represent a novel mechanism for regulating the activity of BRMS1 or its associated cytosolic partnersThis work was supported by Spanish Ministerio de Ciencia y Tecnología (Grant SAF2006-10269), Ministerio de Ciencia e Innovación (Grant SAF2008-04048-E) and by a grant from Fundación Mutua Madrileña.Peer reviewe

Kin-cohort estimates for familial breast cancer risk in relation to variants in DNA base excision repair, BRCA1 interacting and growth factor genes

BACKGROUND: Subtle functional deficiencies in highly conserved DNA repair or growth regulatory processes resulting from polymorphic variation may increase genetic susceptibility to breast cancer. Polymorphisms in DNA repair genes can impact protein function leading to genomic instability facilitated by growth stimulation and increased cancer risk. Thus, 19 single nucleotide polymorphisms (SNPs) in eight genes involved in base excision repair (XRCC1, APEX, POLD1), BRCA1 protein interaction (BRIP1, ZNF350, BRCA2), and growth regulation (TGFß1, IGFBP3) were evaluated. METHODS: Genomic DNA samples were used in Taqman 5'-nuclease assays for most SNPs. Breast cancer risk to ages 50 and 70 were estimated using the kin-cohort method in which genotypes of relatives are inferred based on the known genotype of the index subject and Mendelian inheritance patterns. Family cancer history data was collected from a series of genotyped breast cancer cases (N = 748) identified within a cohort of female US radiologic technologists. Among 2,430 female first-degree relatives of cases, 190 breast cancers were reported. RESULTS: Genotypes associated with increased risk were: XRCC1 R194W (WW and RW vs. RR, cumulative risk up to age 70, risk ratio (RR) = 2.3; 95% CI 1.3–3.8); XRCC1 R399Q (QQ vs. RR, cumulative risk up to age 70, RR = 1.9; 1.1–3.9); and BRIP1 (or BACH1) P919S (SS vs. PP, cumulative risk up to age 50, RR = 6.9; 1.6–29.3). The risk for those heterozygous for BRCA2 N372H and APEX D148E were significantly lower than risks for homozygotes of either allele, and these were the only two results that remained significant after adjusting for multiple comparisons. No associations with breast cancer were observed for: APEX Q51H; XRCC1 R280H; IGFPB3 -202A>C; TGFß1 L10P, P25R, and T263I; BRCA2 N289H and T1915M; BRIP1 -64A>C; and ZNF350 (or ZBRK1) 1845C>T, L66P, R501S, and S472P. CONCLUSION: Some variants in genes within the base-excision repair pathway (XRCC1) and BRCA1 interacting proteins (BRIP1) may play a role as low penetrance breast cancer risk alleles. Previous association studies of breast cancer and BRCA2 N372H and functional observations for APEX D148E ran counter to our findings of decreased risks. Due to the many comparisons, cautious interpretation and replication of these relationships are warranted

Utilisation of an operative difficulty grading scale for laparoscopic cholecystectomy

Background A reliable system for grading operative difficulty of laparoscopic cholecystectomy would standardise description of findings and reporting of outcomes. The aim of this study was to validate a difficulty grading system (Nassar scale), testing its applicability and consistency in two large prospective datasets. Methods Patient and disease-related variables and 30-day outcomes were identified in two prospective cholecystectomy databases: the multi-centre prospective cohort of 8820 patients from the recent CholeS Study and the single-surgeon series containing 4089 patients. Operative data and patient outcomes were correlated with Nassar operative difficultly scale, using Kendall’s tau for dichotomous variables, or Jonckheere–Terpstra tests for continuous variables. A ROC curve analysis was performed, to quantify the predictive accuracy of the scale for each outcome, with continuous outcomes dichotomised, prior to analysis. Results A higher operative difficulty grade was consistently associated with worse outcomes for the patients in both the reference and CholeS cohorts. The median length of stay increased from 0 to 4 days, and the 30-day complication rate from 7.6 to 24.4% as the difficulty grade increased from 1 to 4/5 (both p < 0.001). In the CholeS cohort, a higher difficulty grade was found to be most strongly associated with conversion to open and 30-day mortality (AUROC = 0.903, 0.822, respectively). On multivariable analysis, the Nassar operative difficultly scale was found to be a significant independent predictor of operative duration, conversion to open surgery, 30-day complications and 30-day reintervention (all p < 0.001). Conclusion We have shown that an operative difficulty scale can standardise the description of operative findings by multiple grades of surgeons to facilitate audit, training assessment and research. It provides a tool for reporting operative findings, disease severity and technical difficulty and can be utilised in future research to reliably compare outcomes according to case mix and intra-operative difficulty

The Alcohol Intervention Training Program (AITP): A response to alcohol misuse in the farming community

Background Farm men and women in Australia have higher levels of problematic alcohol use than their urban counterparts and experience elevated health risks associated with excessive alcohol consumption. The Sustainable Farm Families (SFF) program has worked successfully with farm men and women to address health, well- being and safety and has identified that further research and training is required to understand and address alcohol misuse behaviours. This project will add an innovative component to the program by training health professionals working with farm men and women to discuss and respond to alcohol-related physical and mental health problems. Methods/Design A mixed method design with multi-level evaluation will be implemented following the development and delivery of a training program (The Alcohol Intervention Training Program {AITP}) for Sustainable Farm Families health professionals. Pre-, post- and follow-up surveys will be used to assess both the impact of the training on the knowledge, confidence and skills of the health professionals to work with alcohol misuse and associated problems, and the impact of the training on the attitudes, behaviour and mental health of farm men and women who participate in the SFF project. Evaluations will take a range of forms including self-rated outcome measures and interviews. Discussion The success of this project will enhance the health and well-being of a critical population, the farm men and women of Australia, by producing an evidence-based strategy to assist them to adopt more positive alcohol-related behaviours that will lead to better physical and mental health