475 research outputs found
Flowering of kiwifruit (Actinidia deliciosa) is reduced by long photoperiods
Mature kiwifruit (Actinidia deliciosa ‘Hayward’) vines grown under standard orchard management were exposed to 16-h photoperiods from the longest day in summer until after leaf fall in autumn. Photoperiod extension was achieved with tungsten halogen lamps that produced 2–8 µmols m–2 s–1 photosynthetically active radiation. Long day treatments did not affect fruit dry matter or fruit weight at harvest during the growing season that the treatments were applied or during the following growing season. However, flowering was reduced by 22% during the spring following treatment application. As this reduction in flowering was not accompanied by a decrease in budbreak, the long day effect is not consistent with a delay in the onset of winter chilling. It is suggested therefore, that the observed reduction in flowering may be because of a diminution of floral evocation
Adaptation to Walking Direction in Biological Motion
The direction that we see another person walking provides us with an important cue to their intentions, but little is known about how the brain encodes walking direction across a neuronal population. The current study used an adaptation technique to investigate the sensory coding of perceived walking direction. We measured perceived walking direction of point-light stimuli before and after adaptation, and found that adaptation to a specific walking direction resulted in repulsive perceptual aftereffects. The magnitude of these aftereffects was tuned to the walking direction of the adaptor relative to the test, with local repulsion of perceived walking direction for test stimuli oriented on either side of the adapted walking direction. The specific tuning profiles that we observed are well explained by a population-coding model, in which perceived walking direction is coded in terms of the relative activity across a bank of sensory channels with peak tuning distributed across the full 360° range of walking directions. Further experiments showed specificity in how horizontal (azimuth) walking direction is coded when moving away from the observer compared to when moving toward the observer. Moreover, there was clear specificity in these perceptual aftereffects for walking direction compared to a nonbiological form of 3D motion (a rotating sphere). These results indicate the existence of neural mechanisms in the human visual system tuned to specific walking directions, provide insight into the number of sensory channels and how their responses are combined to encode walking direction, and demonstrate the specificity of adaptation to biological motion
Design of Phase 3 Studies Evaluating Vixotrigine for Treatment of Trigeminal Neuralgia
Purpose: Vixotrigine (BIIB074) is a voltage- and use-dependent sodium channel blocker. These studies will evaluate the efficacy and safety of vixotrigine in treating pain experienced by patients with trigeminal neuralgia (TN) using enriched enrollment randomized withdrawal trial designs.
Patients and Methods: Two double-blind randomized withdrawal studies are planned to evaluate the efficacy and safety of vixotrigine compared with placebo in participants with TN (NCT03070132 and NCT03637387). Participant criteria include ≥ 18 years old who have classical, purely paroxysmal TN diagnosed ≥ 3 months prior to study entry, who experience ≥ 3 paroxysms of pain/day. The two studies will include a screening period, 7-day run-in period, a 4- or 6-week single-dose-blind dose-optimization period (Study 1) or 4-week open-label period (Study 2), and 14-week double-blind period. Participants will receive vixotrigine 150 mg orally three times daily in the dose-optimization and open-label periods. The primary endpoint of both studies is the proportion of participants classified as responders at Week 12 of the double-blind period. Secondary endpoints include safety measures, quality of life, and evaluation of vixotrigine population pharmacokinetics.
Conclusion: There is a need for an effective, well-tolerated, noninvasive treatment for the neuropathic pain associated with TN. The proposed studies will evaluate the efficacy and safety of vixotrigine in treating pain experienced by patients with TN
Clinicopathological Profile and Surgical Treatment of Abdominal Tuberculosis: A Single Centre Experience in Northwestern Tanzania.
Abdominal tuberculosis continues to be a major public health problem worldwide and poses diagnostic and therapeutic challenges to general surgeons practicing in resource-limited countries. This study was conducted to describe the clinicopathological profile and outcome of surgical treatment of abdominal tuberculosis in our setting and compare with what is described in literature. A prospective descriptive study of patients who presented with abdominal tuberculosis was conducted at Bugando Medical Centre (BMC) in northwestern Tanzania from January 2006 to February 2012. Ethical approval to conduct the study was obtained from relevant authorities. Statistical data analysis was performed using SPSS version 17.0. Out of 256 patients enrolled in the study, males outnumbered females. The median age was 28 years (range = 16-68 years). The majority of patients (77.3%) had primary abdominal tuberculosis. A total of 127 (49.6%) patients presented with intestinal obstruction, 106 (41.4%) with peritonitis, 17 (6.6%) with abdominal masses and 6 (2.3%) patients with multiple fistulae in ano. Forty-eight (18.8%) patients were HIV positive. A total of 212 (82.8%) patients underwent surgical treatment for abdominal tuberculosis. Bands /adhesions (58.5%) were the most common operative findings. Ileo-caecal region was the most common bowel involved in 122 (57.5%) patients. Release of adhesions and bands was the most frequent surgical procedure performed in 58.5% of cases. Complication and mortality rates were 29.7% and 18.8% respectively. The overall median length of hospital stay was 32 days and was significantly longer in patients with complications (p < 0.001). Advanced age (age ≥ 65 years), co-morbid illness, late presentation, HIV positivity and CD4+ count < 200 cells/μl were statistically significantly associated with mortality (p < 0.0001). The follow up of patients were generally poor as only 37.5% of patients were available for follow up at twelve months after discharge. Abdominal tuberculosis constitutes a major public health problem in our environment and presents a diagnostic challenge requiring a high index of clinical suspicion. Early diagnosis, early anti-tuberculous therapy and surgical treatment of the associated complications are essential for survival
Extracellular Matrix Aggregates from Differentiating Embryoid Bodies as a Scaffold to Support ESC Proliferation and Differentiation
Embryonic stem cells (ESCs) have emerged as potential cell sources for tissue engineering and regeneration owing to its virtually unlimited replicative capacity and the potential to differentiate into a variety of cell types. Current differentiation strategies primarily involve various growth factor/inducer/repressor concoctions with less emphasis on the substrate. Developing biomaterials to promote stem cell proliferation and differentiation could aid in the realization of this goal. Extracellular matrix (ECM) components are important physiological regulators, and can provide cues to direct ESC expansion and differentiation. ECM undergoes constant remodeling with surrounding cells to accommodate specific developmental event. In this study, using ESC derived aggregates called embryoid bodies (EB) as a model, we characterized the biological nature of ECM in EB after exposure to different treatments: spontaneously differentiated and retinoic acid treated (denoted as SPT and RA, respectively). Next, we extracted this treatment-specific ECM by detergent decellularization methods (Triton X-100, DOC and SDS are compared). The resulting EB ECM scaffolds were seeded with undifferentiated ESCs using a novel cell seeding strategy, and the behavior of ESCs was studied. Our results showed that the optimized protocol efficiently removes cells while retaining crucial ECM and biochemical components. Decellularized ECM from SPT EB gave rise to a more favorable microenvironment for promoting ESC attachment, proliferation, and early differentiation, compared to native EB and decellularized ECM from RA EB. These findings suggest that various treatment conditions allow the formulation of unique ESC-ECM derived scaffolds to enhance ESC bioactivities, including proliferation and differentiation for tissue regeneration applications. © 2013 Goh et al
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Letter processing and font information during reading: beyond distinctiveness, where vision meets design
Letter identification is a critical front end of the
reading process. In general, conceptualizations of the identification process have emphasized arbitrary sets of distinctive features. However, a richer view of letter processing incorporates principles from the field of type design, including an emphasis on uniformities across letters within a font. The importance of uniformities is supported by a small body of research indicating that consistency of font increases letter identification efficiency. We review design concepts and the relevant literature, with the goal of stimulating further thinking about letter processing during reading
Clinical utility of C-reactive protein-based triage for presumptive pulmonary tuberculosis in South African adults.
BACKGROUND: Identification of an accurate, low-cost triage test for pulmonary TB among people presenting to healthcare facilities is an urgent global research priority. We assessed the diagnostic accuracy and clinical utility of C-reactive protein (CRP) for TB triage among symptomatic adult outpatients, irrespective of HIV status. METHODS: We prospectively enrolled adults reporting at least one (for people with HIV) or two (for people without HIV) symptoms of cough, fever, night sweats, or weight loss at two TB clinics in Cape Town, South Africa. Participants provided sputum for culture and Xpert MTB/RIF Ultra. We evaluated the diagnostic accuracy of CRP (measured using a laboratory-based assay) against a TB-culture reference standard as the area under the receiver operating characteristic curve (AUROC), and sensitivity and specificity at pre-specified thresholds. We assessed clinical utility using decision curve analysis and benchmarked against WHO recommendations. RESULTS: Of 932 included individuals, 255 (27%) had culture-confirmed pulmonary TB and 389 (42%) were living with HIV. CRP demonstrated an AUROC of 0·80 (95% confidence interval 0·77-0·83), with sensitivity 93% (89-95%) and specificity 54% (50-58%) using a primary cut-off of ≥10 mg/L. Performance was similar among people with HIV to those without. In decision curve analysis, CRP-based triage offered greater clinical utility than confirmatory testing for all up to a number willing to test threshold of 20 confirmatory tests per true positive pulmonary TB case diagnosed (threshold probability 5%). If it is possible to perform more confirmatory tests than this, a 'confirmatory test for all' strategy performed better. CONCLUSIONS: CRP achieved the WHO-defined sensitivity, but not specificity, targets for a triage test for pulmonary TB and showed evidence of clinical utility among symptomatic outpatients, irrespective of HIV status. FUNDING: South African Medical Research Council, EDCTP2, Royal Society Newton Advanced Fellowship, Wellcome Trust, National Institute of Health Research, Royal College of Physicians
miR-Q: a novel quantitative RT-PCR approach for the expression profiling of small RNA molecules such as miRNAs in a complex sample
<p>Abstract</p> <p>Background</p> <p>MicroRNAs (miRNAs) are small endogenous non-coding interfering RNA molecules regarded as major regulators in eukaryotic gene expression. Different methods are employed for miRNA expression profiling. For a better understanding of their role in essential biological processes, convenient methods for differential miRNA expression analysis are required.</p> <p>Results</p> <p>Here, we present the miR-Q assay as a highly sensitive quantitative reverse transcription PCR (qRT-PCR) for expression analysis of small RNAs such as miRNA molecules. It shows a high dynamic range of 6 to 8 orders of magnitude comprising a sensitivity of up to 0.2 fM miRNA, which corresponds to single copies per cell. There is nearly no cross reaction among closely-related miRNA family members, which points to the high specificity of the assays. Using this approach, we quantified the expression of let-7b in different human cell lines as well as miR-145 and miR-21 expression in porcine intestinal samples.</p> <p>Conclusion</p> <p>miR-Q is a cost-effective and highly specific approach, which neither requires the use of fluorochromic probes, nor Locked Nucleic Acid (LNA)-modified oligonucleotides. Moreover, it provides a remarkable increase in specificity and simplified detection of small RNAs.</p
Synthetic long oligonucleotides to generate artificial templates for use as positive controls in molecular assays: drug resistance mutations in influenza virus as an example
<p>Abstract</p> <p>Background</p> <p>Positive controls are an integral component of any sensitive molecular diagnostic tool, but this can be affected, if several mutations are being screened in a scenario of a pandemic or newly emerging disease where it can be difficult to acquire all the necessary positive controls from the host. This work describes the development of a synthetic oligo-cassette for positive controls for accurate and highly sensitive diagnosis of several mutations relevant to influenza virus drug resistance.</p> <p>Results</p> <p>Using influenza antiviral drug resistance mutations as an example by employing the utility of synthetic paired long oligonucleotides containing complementary sequences at their 3' ends and utilizing the formation of oligonucleotide dimers and DNA polymerization, we generated ~170bp dsDNA containing several known specific neuraminidase inhibitor (NAI) resistance mutations. These templates were further cloned and successfully applied as positive controls in downstream assays.</p> <p>Conclusion</p> <p>This approach significantly improved the development of diagnosis of resistance mutations in terms of time, accuracy, efficiency and sensitivity, which are paramount to monitoring the emergence and spread of antiviral drug resistant influenza strains. Thus, this may have a significantly broader application in molecular diagnostics along with its application in rapid molecular testing of all relevant mutations in an event of pandemic.</p
Effects of Meal Frequency on Metabolic Profiles and Substrate Partitioning in Lean Healthy Males
The daily number of meals has an effect on postprandial glucose and insulin responses, which may affect substrate partitioning and thus weight control. This study investigated the effects of meal frequency on 24 h profiles of metabolic markers and substrate partitioning.Twelve (BMI:21.6 ± 0.6 kg/m(2)) healthy male subjects stayed after 3 days of food intake and physical activity standardization 2 × 36 hours in a respiration chamber to measure substrate partitioning. All subjects randomly received two isoenergetic diets with a Low meal Frequency (3 ×; LFr) or a High meal Frequency (14 ×; HFr) consisting of 15 En% protein, 30 En% fat, and 55 En% carbohydrates. Blood was sampled at fixed time points during the day to measure metabolic markers and satiety hormones.Glucose and insulin profiles showed greater fluctuations, but a lower AUC of glucose in the LFr diet compared with the HFr diet. No differences between the frequency diets were observed on fat and carbohydrate oxidation. Though, protein oxidation and RMR (in this case SMR + DIT) were significantly increased in the LFr diet compared with the HFr diet. The LFr diet increased satiety and reduced hunger ratings compared with the HFr diet during the day.The higher rise and subsequently fall of insulin in the LFr diet did not lead to a higher fat oxidation as hypothesized. The LFr diet decreased glucose levels throughout the day (AUC) indicating glycemic improvements. RMR and appetite control increased in the LFr diet, which can be relevant for body weight control on the long term.ClinicalTrials.gov NCT01034293
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