Mitigating susceptibility-induced distortions in high-resolution 3DEPI fMRI at 7T

Geometric distortion is a major limiting factor for spatial specificity in high-resolution fMRI using EPI readouts and is exacerbated at higher field strengths due to increased B0 field inhomogeneity. Prominent correction schemes are based on B0 field-mapping or acquiring reverse phase-encoded (reversed-PE) data. However, to date, comparisons of these techniques in the context of fMRI have only been performed on 2DEPI data, either at lower field or lower resolution. In this study, we investigate distortion compensation in the context of sub-millimetre 3DEPI data at 7T. B0 field-mapping and reversed-PE distortion correction techniques were applied to both partial coverage BOLD-weighted and whole brain MT-weighted 3DEPI data with matched distortion. Qualitative assessment showed overall improvement in cortical alignment for both correction techniques in both 3DEPI fMRI and whole-brain MT-3DEPI datasets. The distortion-corrected MT-3DEPI images were quantitatively evaluated by comparing cortical alignment with an anatomical reference using dice coefficient (DC) and correlation ratio (CR) measures. These showed that B0 field-mapping and reversed-PE methods both improved correspondence between the MT-3DEPI and anatomical data, with more substantial improvements consistently obtained using the reversed-PE approach. Regional analyses demonstrated that the largest benefit of distortion correction, and in particular of the reversed-PE approach, occurred in frontal and temporal regions where susceptibility-induced distortions are known to be greatest, but had not led to complete signal dropout. In conclusion, distortion correction based on reversed-PE data has shown the greater capacity for achieving faithful alignment with anatomical data in the context of high-resolution fMRI at 7T using 3DEPI

The appropriateness of gatekeeping in the provision of reproductive health care for adolescents in Lithuania:the general practice perspective

BACKGROUND: Adolescents' consultation of primary health care services remains problematic despite their accessibility. The reproductive health service seeking behavior of adolescents is the object of much research but little is known about how this behavior is influenced by the gatekeeping system. This study aimed to explore general practitioners' perceptions of the appropriateness of gatekeeping in adolescent reproductive health care. METHODS: Twenty in-depth interviews regarding factors affecting adolescent reproductive health care were carried out on a diverse sample of general practitioners and analyzed using grounded theory. RESULTS: The analysis identified several factors that shaped GPs' negative attitude to gatekeeping in adolescent reproductive health care. Its appropriateness in this field was questionable due to a lack of willingness on the part of GPs to provide reproductive health services for teenagers, their insufficient training, inadequately equipped surgeries and low perceived support for reproductive health service provision. CONCLUSION: Since factors for improving adolescent reproductive health concern not only physicians but also the health system and policy levels, complex measures should be designed to overcome these barriers. Discussion of a flexible model of gatekeeping, encompassing both co-ordination of care provided by GPs and the possibility of patients' self-referral, should be included in the political agenda. Adolescents tend to under-use rather than over-use reproductive health services and every effort should be made to facilitate the accessibility of such services

Evaluation of the effects of sensory denervation on osteoblasts by 3 H-proline autoradiography

The inferior alveolar nerve was unilaterally resected in 30-day-old mice; other animals were unilaterally sham-operated. At 15, 30, 60, 90, or 150 days after surgery, the mice were injected with 2μCi of 3 H-proline (sp. act. 1.0 Ci/mM) per g of body weight and killed 15, 30, or 60 min later. Autoradiographs were prepared from 5μm decalcified sagittal sections of mandibles and grain counts made over periosteal osteoblasts mesial to the first molar. In denervated mandibles, osteoblasts incorporated less isotope compared to controls with differences being maximal at the early intervals. These differences became attenuated with time, possibly due to an intrinsic compensatory mechanism, secondary to neurotrophic regulation.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47675/1/441_2004_Article_BF00219365.pd

A Practical Guide to Rodent Islet Isolation and Assessment

Pancreatic islets of Langerhans secrete hormones that are vital to the regulation of blood glucose and are, therefore, a key focus of diabetes research. Purifying viable and functional islets from the pancreas for study is an intricate process. This review highlights the key elements involved with mouse and rat islet isolation, including choices of collagenase, the collagenase digestion process, purification of islets using a density gradient, and islet culture conditions. In addition, this paper reviews commonly used techniques for assessing islet viability and function, including visual assessment, fluorescent markers of cell death, glucose-stimulated insulin secretion, and intracellular calcium measurements. A detailed protocol is also included that describes a common method for rodent islet isolation that our laboratory uses to obtain viable and functional mouse islets for in vitro study of islet function, beta-cell physiology, and in vivo rodent islet transplantation. The purpose of this review is to serve as a resource and foundation for successfully procuring and purifying high-quality islets for research purposes

Extracellular DNA Chelates Cations and Induces Antibiotic Resistance in Pseudomonas aeruginosa Biofilms

Biofilms are surface-adhered bacterial communities encased in an extracellular matrix composed of DNA, bacterial polysaccharides and proteins, which are up to 1000-fold more antibiotic resistant than planktonic cultures. To date, extracellular DNA has been shown to function as a structural support to maintain Pseudomonas aeruginosa biofilm architecture. Here we show that DNA is a multifaceted component of P. aeruginosa biofilms. At physiologically relevant concentrations, extracellular DNA has antimicrobial activity, causing cell lysis by chelating cations that stabilize lipopolysaccharide (LPS) and the outer membrane (OM). DNA-mediated killing occurred within minutes, as a result of perturbation of both the outer and inner membrane (IM) and the release of cytoplasmic contents, including genomic DNA. Sub-inhibitory concentrations of DNA created a cation-limited environment that resulted in induction of the PhoPQ- and PmrAB-regulated cationic antimicrobial peptide resistance operon PA3552–PA3559 in P. aeruginosa. Furthermore, DNA-induced expression of this operon resulted in up to 2560-fold increased resistance to cationic antimicrobial peptides and 640-fold increased resistance to aminoglycosides, but had no effect on β-lactam and fluoroquinolone resistance. Thus, the presence of extracellular DNA in the biofilm matrix contributes to cation gradients, genomic DNA release and inducible antibiotic resistance. DNA-rich environments, including biofilms and other infection sites like the CF lung, are likely the in vivo environments where extracellular pathogens such as P. aeruginosa encounter cation limitation

A qualitative study on healthcare professionals’ perceived barriers to insulin initiation in a multi-ethnic population

Background: Nationwide surveys have shown that the prevalence of diabetes rates in Malaysia have almost doubled in the past ten years; yet diabetes control remains poor and insulin therapy is underutilized. This study aimed to explore healthcare professionals’ views on barriers to starting insulin therapy in people with type 2 diabetes. Methods: Healthcare professionals consisting of general practitioners (n = 11), family medicine specialists (n = 10), medical officers (n = 8), government policy makers (n = 4), diabetes educators (n = 3) and endocrinologists (n = 2) were interviewed. A semi-structured topic guide was used to guide the interviews by trained facilitators. The interviews were transcribed verbatim and analysed using a thematic analysis approach. Results: Insulin initiation was found to be affected by patient, healthcare professional and system factors. Patients’ barriers include culture-specific barriers such as the religious purity of insulin, preferred use of complementary medication and perceived lethality of insulin therapy. Healthcare professionals’ barriers include negative attitudes towards insulin therapy and the ‘legacy effect’ of old insulin guidelines; whilst system barriers highlight the lack of resources, language and communication challenges. Conclusions: Tackling the issue of insulin initiation should not only happen during clinical consultations. It requires health education to emphasise the progressive nature of diabetes and the eventuality of insulin therapy at early stage of the illness. Healthcare professionals should be trained how to initiate insulin and communicate effectively with patients from various cultural and religious backgrounds

What do clinicians want? Interest in integrative health services at a North Carolina academic medical center

BACKGROUND: Use of complementary medicine is common, consumer driven and usually outpatient focused. We wished to determine interest among the medical staff at a North Carolina academic medical center in integrating diverse therapies and services into comprehensive care. METHODS: We conducted a cross sectional on-line survey of physicians, nurse practitioners and physician assistants at a tertiary care medical center in 2006. The survey contained questions on referrals and recommendations in the past year and interest in therapies or services if they were to be provided at the medical center in the future. RESULTS: Responses were received from 173 clinicians in 26 different departments, programs and centers. There was strong interest in offering several specific therapies: therapeutic exercise (77%), expert consultation about herbs and dietary supplements (69%), and massage (66%); there was even stronger interest in offering comprehensive treatment programs such as multidisciplinary pain management (84%), comprehensive nutritional assessment and advice (84%), obesity/healthy lifestyle promotion (80%), fit for life (exercise and lifestyle program, 76%), diabetes healthy lifestyle promotion (73%); and comprehensive psychological services for stress management, including hypnosis and biofeedback (73%). CONCLUSION: There is strong interest among medical staff at an academic health center in comprehensive, integrated services for pain, obesity, and diabetes and in specific services in fitness, nutrition and stress management. Future studies will need to assess the cost-effectiveness of such services, as well as their financial sustainability and impact on patient satisfaction, health and quality of life

Evolution of a Signaling Nexus Constrained by Protein Interfaces and Conformational States

Heterotrimeric G proteins act as the physical nexus between numerous receptors that respond to extracellular signals and proteins that drive the cytoplasmic response. The Gα subunit of the G protein, in particular, is highly constrained due to its many interactions with proteins that control or react to its conformational state. Various organisms contain differing sets of Gα-interacting proteins, clearly indicating that shifts in sequence and associated Gα functionality were acquired over time. These numerous interactions constrained much of Gα evolution; yet Gα has diversified, through poorly understood processes, into several functionally specialized classes, each with a unique set of interacting proteins. Applying a synthetic sequence-based approach to mammalian Gα subunits, we established a set of seventy-five evolutionarily important class-distinctive residues, sites where a single Gα class is differentiated from the three other classes. We tested the hypothesis that shifts at these sites are important for class-specific functionality. Importantly, we mapped known and well-studied class-specific functionalities from all four mammalian classes to sixteen of our class-distinctive sites, validating the hypothesis. Our results show how unique functionality can evolve through the recruitment of residues that were ancestrally functional. We also studied acquisition of functionalities by following these evolutionarily important sites in non-mammalian organisms. Our results suggest that many class-distinctive sites were established early on in eukaryotic diversification and were critical for the establishment of new Gα classes, whereas others arose in punctuated bursts throughout metazoan evolution. These Gα class-distinctive residues are rational targets for future structural and functional studies