Quantitative measurement of cerebral physiology using respiratory-calibrated MRI

Functional magnetic resonance imaging typically measures signal increases arising from changes in the transverse relaxation rate over small regions of the brain and associates these with local changes in cerebral blood flow, blood volume and oxygen metabolism. Recent developments in pulse sequences and image analysis methods have improved the specificity of the measurements by focussing on changes in blood flow or changes in blood volume alone. However, FMRI is still unable to match the physiological information obtainable from positron emission tomography (PET), which is capable of quantitative measurements of blood flow and volume, and can indirectly measure resting metabolism. The disadvantages of PET are its cost, its availability, its poor spatial resolution and its use of ionising radiation. The MRI techniques introduced here address some of these limitations and provide physiological data comparable with PET measurements. We present an 18-minute MRI protocol that produces multi-slice whole-brain coverage and yields quantitative images of resting cerebral blood flow, cerebral blood volume, oxygen extraction fraction, CMRO(2), arterial arrival time and cerebrovascular reactivity of the human brain in the absence of any specific functional task. The technique uses a combined hyperoxia and hypercapnia paradigm with a modified arterial spin labelling sequence.

Analysis of clinical data of patients with different outcomes after short-time insemination

The study is to analyse the clinical data of the two groups of patients with different fertilisation outcomes after short-time insemination and probe into short-time insemination indications. A retrospective study including 558 cycles of short-time insemination in our centre during January 2009 to June 2010 which were divided into two groups by the method of fertilisation, 472 cycles by IVF and 86 cycles by Re-ICSI group according to fertilisation conditions to and compare the differences between the two groups in the indexes of average female age, average male age, duration of infertility, forward-moving sperm counts, abnormal sperm rate, proportion of primary infertility, etc. The differences between the two groups have statistical significance in duration of infertility, forward-moving sperm counts, abnormal sperm rate and proportion of primary infertility (5.02 ± 3.12 versus 5.86 ± 3.35; 83.06 ± 78.55 versus 54.02 ± 61.78; 83.56 ± 5.24% versus 86.31 ± 5.26%; 56.87% versus 74.42%; P < 0.05). The discrepancy between the two groups has no statistical significance in average female age and average male age (P > 0.05). Duration of infertility, forward-moving sperm counts, abnormal sperm rate and previous pregnancy history have great significance to predict fertilisation failure, so decisions should be made on the basis of the above indexes when evaluating whether a patient should conduct short-time insemination.

Bactericidal activity of grass carp Ctenopharyngodon idella C9-deficient serum against Aeromonas hydrophila

Neutralizing complement C9 in grass carp Ctenopharyngodon idella sera with rabbit anti-C9 sera against fish complement C9, demonstrated that bactericidal activity against Aeromonas hydrophila of the C9-deficient fish sera was greatly impaired. These results indicated that the fish complement C9 plays a key role in pathogen killing through the lytic pathway.

Dust trajectory sensor: accuracy and data analysis

The Dust Trajectory Sensor (DTS) instrument is developed for the measurement of the velocity vector of cosmic dust particles. The trajectory information is imperative in determining the particles' origin and distinguishing dust particles from different sources. The velocity vector also reveals information on the history of interaction between the charged dust particle and the magnetospheric or interplanetary space environment. The DTS operational principle is based on measuring the induced charge from the dust on an array of wire electrodes. In recent work, the DTS geometry has been optimized [S. Auer, E. Grün, S. Kempf, R. Srama, A. Srowig, Z. Sternovsky, and V Tschernjawski, Rev. Sci. Instrum. 79, 084501 (2008)] and a method of triggering was developed [S. Auer, G. Lawrence, E. Grün, H. Henkel, S. Kempf, R. Srama, and Z. Sternovsky, Nucl. Instrum. Methods Phys. Res. A 622, 74 (2010)]. This article presents the method of analyzing the DTS data and results from a parametric study on the accuracy of the measurements. A laboratory version of the DTS has been constructed and tested with particles in the velocity range of 2-5 km/s using the Heidelberg dust accelerator facility. Both the numerical study and the analyzed experimental data show that the accuracy of the DTS instrument is better than about 1% in velocity and 1° in direction.

Number needed to treat and treatment cost per fracture avoided with denosumab compared with zoledronic acid in patients with breast cancer with bone metastases

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Background: Pathologic fractures (PF) are a common and expensive-to-treat skeletal-related event (SRE), which affect over two-thirds of metastatic breast cancer (MBC) patients, and cost $26,936 (2009 US dollars) per event on average for inpatient treatment. In a phase III trial ( NCT20050136 ), MBC patients randomized to denosumab (Dmab; n=1,026) demonstrated longer time to SRE, but comparable rates of survival and disease progression relative to those randomized to zoledronic acid (ZOL; n=1,020). We calculated the number needed to treat (NNT) to avoid one PF and the treatment cost per PF avoided with Dmab vs. ZOL in MBC patients.

Methods: Phase III trial results from the Dmab product label were used to determine the rate of PFs and SREs in MBC patients treated with Dmab vs. ZOL. Treatment cost included only the wholesale acquisition cost of Dmab and ZOL, and assumed 12 months of treatment. The NNT calculated the number of patients who would need to be treated with Dmab vs. ZOL to avoid one additional PF. Sensitivity analyses included expanding the treatment outcome from PFs to SREs and adding drug administration costs for Dmab and ZOL, and, renal monitoring costs only for ZOL.

Results: Based on the estimated differences in PF risk of 2.7%, 37.4 patients would need to be treated with Dmab vs. ZOL to avoid one additional PF, resulting in a treatment cost per PF avoided of $346,911. The lower 95% confidence limit for the cost per PF avoided with Dmab vs. ZOL was $148,114, which is significantly greater than the mean inpatient cost of treating a PF event. Including drug administration and renal monitoring costs led to a cost per PF avoided of $323,069. Expanding the treatment outcome from PFs to SREs showed that 17.3 patients would need to be treated with Dmab vs. ZOL to avoid one additional SRE (95% CI: 10.2 to 59.7; absolute risk reduction 5.8%), resulting in a treatment cost of $160,595 per SRE avoided.

Conclusions: PFs have a debilitating effect on patients, and treatment with Dmab compared to ZOL was associated with a treatment cost per PF avoided that exceeded 12 times the mean inpatient cost of a PF. Decision makers need to consider the high costs associated with Dmab prior to formulary inclusion.

Social consensus through the influence of committed minorities

We show how the prevailing majority opinion in a population can be rapidly reversed by a small fraction p of randomly distributed committed agents who consistently proselytize the opposing opinion and are immune to influence. Specifically, we show that when the committed fraction grows beyond a critical value p(c) ≈ 10%, there is a dramatic decrease in the time T(c) taken for the entire population to adopt the committed opinion. In particular, for complete graphs we show that when p < pc, T(c) ~ exp [α(p)N], whereas for p>p(c), T(c) ~ ln N. We conclude with simulation results for Erdős-Rényi random graphs and scale-free networks which show qualitatively similar behavior.

Application of multifocal visual evoked potentials in the assessment of visual dysfunction in macular diseases

PURPOSE

To evaluate the use of AccuMap multifocal visual evoked potentials (mfVEP) in visual dysfunction caused by macular diseases.

METHODS

Forty-eight eyes with known macular diseases underwent AccuMap mfVEP and microperimetry 1 (MP1) assessments. Evaluation of mfVEP abnormality was based on an amplitude deviation probability plot and the AccuMap Severity Index (ASI). Correlation analyses of the mean mfVEP amplitude corresponding to a radius of 2°, 5°, and 10° of the central visual field, minimum angle of resolution best-corrected visual acuity (BCVA), and MP1 mean sensitivity of the corresponding areas were performed.

RESULTS

Among the 48 affected eyes, AccuMap mfVEP detected an abnormality of the central visual field in 45 eyes, with a sensitivity of 93.8%. The mean mfVEP amplitudes within a radius of 2°, 5°, and 10° of the central visual field were found to be positively correlated with BCVA (P<0.01 for all groups). The mean amplitudes also positively correlated with the MP1 mean sensitivity value of the corresponding visual field (P<0.01 for all groups). In the group with stable fixation or predominantly central fixation, the mean mfVEP amplitudes did not correlate with the BCVA or the MP1 mean sensitivity value. Regardless of the fixation status, the ASI was found to correlate with both the BCVA and the total MP1 mean defect value.

CONCLUSION

Objective perimetry using AccuMap mfVEP might be applied in the assessment of macular function, with the ASI offering a potentially useful indicator for evaluating macular dysfunction.

Social influencing and associated random walk models: Asymptotic consensus times on the complete graph

We investigate consensus formation and the asymptotic consensus times in stylized individual- or agent-based models, in which global agreement is achieved through pairwise negotiations with or without a bias. Considering a class of individual-based models on finite complete graphs, we introduce a coarse-graining approach (lumping microscopic variables into macrostates) to analyze the ordering dynamics in an associated random-walk framework. Within this framework, yielding a linear system, we derive general equations for the expected consensus time and the expected time spent in each macro-state. Further, we present the asymptotic solutions of the 2-word naming game and separately discuss its behavior under the influence of an external field and with the introduction of committed agents.

Two novel HLA-A alleles: HLA-A*31:01:09 and HLA-A*33:30

The HLA-A*31:01:09 differs from the closest allele HLAA*31:01:02 by a C to T silent substitution at position 447 in exon 3. The HLA-A*33:30 differs from the closest allele HLA-A*33:03:01 by a single nucleotide substitution at position 453 in exon 3, leading to a change of Arg 131 Cys.

Xeroderma pigmentosum: a rare cause of chorea

Xeroderma pigmentosum (XP) is an uncommon inherited dermatological disorder characterized by a high degree of skin photosensitivity with development of carcinomas at an early age. Neurological manifestations may be encountered in XP but few detailed descriptions have been provided. Here we describe a sister and a brother presenting chorea, dystonia, myoclonus, ataxia and polyneuropathy related to XP.

Molecular cloning and characterization of phospholipase C zeta in equine sperm and testis reveals species-specific differences in expression of catalytically active protein

Oocyte activation at fertilization is brought about by the testis-specific phospholipase C zeta (PLCZ), owing to its ability to induce oscillations in intracellular Ca(2+) concentration ([Ca(2+)](i)). Whereas this is a highly conserved mechanism among mammals, important species-specific differences in PLCZ sequence, activity, and expression have been reported. Thus, the objectives of this research were to clone and characterize the intracellular Ca(2+)-releasing activity and expression of equine PLCZ in sperm and testis. Molecular cloning of equine PLCZ yielded a 1914-bp sequence that translated into a protein of the appropriate size (~73 kDa), as detected with an anti-PLCZ-specific antibody. Microinjection of 1 μg/μl of equine PLCZ cRNA supported [Ca(2+)](i) oscillations in murine oocytes that were of a higher relative frequency than those generated by an equivalent concentration of murine Plcz cRNA. Immunofluorescence revealed expression of PLCZ over the acrosome, equatorial segment, and head-midpiece junction; unexpectedly, PLCZ also localized to the principal piece of the flagellum in all epididymal, uncapacitated, and capacitated sperm. Immunostaining over the acrosome was abrogated after induction of acrosomal exocytosis. Moreover, injection of either sperm heads or tails into mouse oocytes showed that PLCZ in both fractions is catalytically active. Immunohistochemistry on equine testis revealed expression as early as the round spermatid stage, and injection of these cells supported [Ca(2+)](i) oscillations in oocytes. In summary, we report that equine PLCZ displays higher intrinsic intracellular Ca(2+)-releasing activity than murine PLCZ and that catalytically active protein is expressed in round spermatids as well as the sperm flagellum, emphasizing important species-specific differences. Moreover, some of these results may suggest potential novel roles for PLCZ in sperm physiology.