The most significant progresses in the understanding of human brain functions have been possible due to the use of functional magnetic resonance imaging (fMRI), which when used in combination with other standard neuroimaging techniques (i.e., EEG) provides researchers with a potential tool to elucidate many biophysical principles, established previously by animal comparative studies. However, to date, most of the methods proposed in the literature seeking fMRI signs have been limited to the use of a top-down data analysis approach, thus ignoring a pool of physiological facts. In spite of the important contributions achieved by applying these methods to actual data, there is a disproportionate gap between theoretical models and data-analysis strategies while trying to focus on several new prospects, like for example fMRI/EEG data fusion, causality/connectivity patterns, and nonlinear BOLD signal dynamics. In this paper, we propose a new approach which will allow many of the abovementioned hot topics to be addressed in the near future with an underlying interpretability based on bottom-up modeling. In particular, the theta-MAP presented in the paper to test brain activation corresponds very well with the standardized t test of the SPM99 toolbox. Additionally, a new Impulse Response Function (IRF) has been formulated, directly related to the well-established concept of the hemodynamics response function (HRF). The model uses not only the information contained in the signal but also that in the structure of the background noise to simultaneously estimate the IRF and the autocorrelation function (ACF) by using an autoregressive (AR) model with a filtered Poisson process driving the dynamics. The short-range contributions of voxels within the near-neighborhood are also included, and the potential drift was characterized by a polynomial series. Since our model originated from an immediate extension of the hemodynamics approach [Friston, K.J., Mechelli, A., Turner, R., Price C.J. (2000a). Nonlinear responses in fMRI: the balloon model, volterra kernels, and other hemodynamics. NeuroImage 12, 466-477.], a natural interpretability of the results is feasible.

OBJECTIVE

To evaluate the feasibility and health-related content validity of 6 health-related fitness (HRF) and 3 functional performance (FP) tests among middle-aged and older persons.

METHODS

Cross-sectional methodologic study.

METHODS

Field laboratories in 3 communities of northeast Finland.

METHODS

A regionally representative, community-based cohort of 55- to 79-year-old men (n=501) and women (n=632).

METHODS

Not applicable.

METHODS

Health-related test exclusion rates (%) by age groups and odds ratios (ORs) of subjective health outcomes by fitness categories (least 20%, next 40%, most fit 40%).

RESULTS

The health-related test exclusion rates increased with age, mainly because of musculoskeletal health limitations among the women and cardiovascular and musculoskeletal health limitations among the men. With the exception of dynamic back extension, 1-leg squat, 1-leg standing balance, and the 1-km walk among the women 75 years and older, 85% or more of the subjects qualified for the HRF tests and 95% or more for the FP tests. Strong and graded associations were found for cardiorespiratory and musculoskeletal fitness and the FP test levels with perceived health and functional ability status among both the men and the women (OR range, 2-31). The motor fitness test level was primarily associated with functional ability status.

CONCLUSIONS

All the HRF and FP tests showed health-related content validity, and 4 of 6 of the HRF tests and all of the FP tests proved to be safe, with minor health-related test exclusions for middle-aged and older adults. The findings may help to target physical activity intervention toward persons at high risk for declining health and functional ability.

Functional near-infrared spectroscopy (fNIRS) is a non-invasive neuroimaging modality that measures the concentration changes of oxy-hemoglobin (HbO) and de-oxy hemoglobin (HbR) at the same time. It is an emerging cortical imaging modality with a good temporal resolution that is acceptable for brain-computer interface applications. Researchers have developed several methods in last two decades to extract the neuronal activation related waveform from the observed fNIRS time series. But still there is no standard method for analysis of fNIRS data. This article presents a brief review of existing methodologies to model and analyze the activation signal. The purpose of this review article is to give a general overview of variety of existing methodologies to extract useful information from measured fNIRS data including pre-processing steps, effects of differential path length factor (DPF), variations and attributes of hemodynamic response function (HRF), extraction of evoked response, removal of physiological noises, instrumentation, and environmental noises and resting/activation state functional connectivity. Finally, the challenges in the analysis of fNIRS signal are summarized.

Translationally Controlled Tumor Protein (TCTP) is an almost ubiquitous protein found in eukaryotes, fundamental for the regulation of development and general growth. The multiple functions of TCTP have been inferred from its involvement in several cell pathways, but the specific function of TCTP is still not known in detail. On the other hand, TCTP seems to respond to a plethora of external signals, and appears to be regulated at the transcriptional and/or translational levels by mechanisms yet to be determined. In the present work, we analyzed the capacity of AtTCTP2 gene products (mRNA and protein) to translocate long distance through tobacco heterografts (transgenic/WT and WT/transgenic). The results indicate that both AtTCTP2 mRNA and protein are capable of moving long distance in both directions (stock-scion and scion-stock) with a tendency for movement from source to sink tissue (stock to scion). Interestingly, aerial roots emerged only in heterografts where the protein was detected in both stock and scion, suggesting a correlation between the presence of AtTCTP2 and aerial root appearance. More detailed analysis showed that these aerial roots harbored the transgene and expressed both transcript and protein. In addition, the protein localization pattern in transgenic aerial and primary roots was basically the same, indicating specific nuclear destination in roots, but also in leaves. These findings provide an approach to understand the role of long-distance movement in the function of plant TCTPs, supporting the notion that some of these act in a non-cell autonomous manner, as the human counterpart, the Histamine Releasing Factor (HRF).

BACKGROUND

Clinical studies comparing the different neuraminidase inhibitors for treatment of at-risk patients with influenza have not been performed. To optimize such treatments, we assessed the efficacy and safety of intravenous peramivir compared with oral oseltamivir in treating seasonal influenza A or B virus infection.

METHODS

A multicenter, randomized, controlled clinical trial was conducted from December 2012 to May 2014 in high-risk patients infected with seasonal influenza. A total of 92 adult inpatients and outpatients with high risk factors (HRFs) were treated by either a single intravenous infusion of peramivir (600 mg) or oral administration of oseltamivir (75 mg, twice per day for 5 days).

RESULTS

The median times to clinical stability (time to reach <37°C) were 40.0 hours (95% confidence interval [CI] = 23.3-64.5) and 37.8 hours (95% CI = 26.3-45.3) in the peramivir and oseltamivir groups, respectively; these values did not reveal a significant difference. The virus titer and change of mean total symptom scores decreased similarly with both treatments. Results of step-wise regression suggested that virus type was a significantly effective prognostic factor with respect to illness resolution. Adverse events (AEs) with peramivir and oseltamivir occurred in 2.2% (n = 1/46) and 13.0% (n = 6/46) of patients, respectively. The severity of AEs was mild in all cases except 2 patients who showed pneumonia or COPD aggravation; both were in the oseltamivir group.

CONCLUSIONS

Intravenous peramivir was effective based on the result of direct comparison with oral oseltamivir. Thus our data show that peramivir is a useful option for the treatment of influenza-infected patients with HRFs.

Homologous restriction factor (HRF) is a 65-kDa membrane protein that inhibits transmembrane channel formation by the membrane-attack complex of complement and by the complement component C9-related cytolytic lymphocyte protein. Stimulation of resting peripheral human lymphocytes with the anti-CD3 monoclonal antibody OKT3 has been shown to induce cytotoxicity in the CD8+ subpopulation. As demonstrated here, OKT3 stimulation also induces expression of cell-surface HRF by CD4+ and CD8+ T lymphocytes. The small proportion of Leu 19+ natural killer lymphocytes present in peripheral blood mononuclear cells was found to express HRF prior to stimulation. Whereas unstimulated peripheral blood mononuclear cells were susceptible to lysis by the membrane-attack complex or by the C9-related protein, OKT3-stimulated peripheral blood mononuclear cells were relatively resistant to both the membrane-attack complex and C9-related protein. This acquired resistance was abrogated by blocking surface HRF with F(ab')2 anti-HRF, suggesting that resistance was due to lymphocyte-membrane HRF. By using solid-phase anti-HRF, a 65-kDa protein was isolated from the activated peripheral blood mononuclear cells and shown to be capable of conferring upon sheep erythrocytes the characteristic activity of human HRF.

In diffuse optical imaging (DOI) data analysis, the functional response is contaminated with physiological noise as in functional magnetic resonance imaging (fMRI). In this work we extend a previously proposed method for fMRI to estimate the parameters of a linear model of DOI time series. The regression is performed in the wavelet domain to infer drift coefficients at different scales and to estimate the strength of the hemodynamic response function (HRF). This multiresolution approach benefits from the whitening property of the discrete wavelet transform (DWT), which approximately decorrelates long-memory noise processes. We also show that a more accurate estimation is obtained by removing some regressors correlating with the protocol. Moreover, we observe that this improvement is related to a quantitative measure of 1/f noise. The performances of the method are first evaluated against a standard spline-cosine drift approach with simulated HRF and real background physiology. Lastly, the technique is applied to experimental event-related data acquired by near-infrared spectroscopy (NIRS).

OBJECTIVE

To improve the interpretation of Heidelberg Retina Flowmeter (HRF; Heidelberg Engineering GmBH, Dosselheim, Germany) flow maps by examining the influence of specific vascular structures and focus depth in the presence and absence of retinal blood flow.

METHODS

HRF flow maps were recorded from the inferior retina of anesthetized Brown Norway rats over a wide range of focus levels, before and after laser occlusion of the retinal circulation. Analysis of the resultant flow maps showed that the sample window was positioned on a retinal artery, arteriole, or vein, or in a retinal capillary area, with or without a visible underlying choroidal vessel. The relationship between HRF-measured flow (arbitrary units) and focus depth was determined for each location. At the conclusion of each experiment, the effect of reduction of systemic blood pressure on the choroidal circulation and the level of background signal in the HRF flow map with no ocular blood flow were assessed.

RESULTS

The strongest flow signals came from the retinal arteries, veins, and arterioles and were reduced to choroidal background level after occlusion of the central retinal artery. Larger choroidal vessels also contributed strong flow signals. In contrast, the flow signal from the retinal capillary area was weak and unaffected by retinal artery occlusion. Changing the depth of focus significantly altered the contribution from the major retinal arteries, arterioles, and veins, but no significant depth effect was seen for retinal capillaries or choroidal vessels. The HRF flow signal remaining when systemic blood pressure was reduced to zero was not significantly different from the capillary sampling location when the eye was normally perfused.

CONCLUSIONS

In the pigmented rat eye, the HRF signal from retinal capillaries is not significantly different from the background noise unrelated to blood flow. Strong flow signals can be obtained from the retinal arteries, retinal arterioles, retinal veins, and choroidal vessels. Current HRF flow maps in the rat therefore reflect blood flow in the larger elements of the microvasculature rather than the capillary network.

BACKGROUND

Hypoxemic respiratory failure (HRF) is one of the most common causes for neonatal infants requiring aggressive respiratory support. Inhaled nitric oxide (iNO) has been established routinely as an adjunct to conventional respiratory support in developed countries. The aim of this study was to investigate effects of iNO in neonates with HRF in resource limited condition with no or limited use of surfactant, high frequency oscillatory ventilation (HFOV) and extracorporeal membrane oxygenation.

METHODS

A non-randomized, open, controlled study of efficacy of iNO was conducted over 18 months. Eligible term and near-term neonates from 28 hospitals with HRF (oxygenation index>> 15) were enrolled prospectively into two groups as either iNO or control. Oxygenation improvement and mortality as primary endpoint were determined in relation with dosing and timing of iNO, severity of underlying diseases, complications and burden. Intention-to-treat principle was adopted for outcome assessment. Response to iNO at 10 or 20 parts per million (ppm) was determined by oxygenation in reference to the control (between-group) and the baseline (within-group).

RESULTS

Compared to 93 controls, initial dose of iNO at 10 ppm in 107 treated infants significantly improved oxygenation from first hour (P = 0.046), with more partial- and non-responders improved oxygenation with subsequent 20 ppm NO (P = 0.018). This effect persisted on days 1 and 3, and resulted in relatively lower mortalities (11.2% vs. 15%) whereas fewer were treated with surfactant (10% vs. 27%), HFOV (< 5%) or postnatal corticosteroids (< 10%) in both groups. The overall outcomes at 28 days of postnatal life in the iNO-treated was not related to perinatal asphyxia, underlying diseases, severity of hypoxemia, or complications, but to the early use of iNO. The cost of hospital stay was not significantly different in both groups.

CONCLUSIONS

With relatively limited use of surfactant and/or HFOV in neonatal HRF, significantly more responders were found in the iNO-treated patients as reflected by improved oxygenation in the first three days over the baseline level. It warrants a randomized, controlled trial for assessment of appropriate timing and long-term outcome of iNO.

OBJECTIVE

The aim of the present study was to determine the association between health-related fitness (HRF) and academic achievement in middle school youth.

METHODS

Subjects were 312 middle school students. HRF was assessed using the FITNESSGRAM test battery. Students were grouped by the number of fitness tests in which they performed within the Healthy Fitness Zone, ranging from <1 test (lowest fitness) to all 5 tests (highest fitness). Academic achievement was assessed using grades (A - F) from four core classes, which were converted to interval data (A=5, F=1) and summed over the academic year and a standardized test (percentile). Maturity offset was calculated to control for the possible effect of maturity status on the association between HRF and academic achievement. Differences in academic achievement among HRF groups were determined using ANOVA.

RESULTS

Grades and standardized test percentiles were higher in HRF group 5 (P<0.01) compared to HRF groups <2, 3, and 4. Cardiorespiratory endurance and muscular strength and endurance were the HRF components most strongly associated with academic achievement.

CONCLUSIONS

HRF was related to academic achievement in youth. Students with the highest fitness level performed better on standardized tests and students with the lowest fitness level performed lower in class grades.

We have employed our CD4(+) T cell model named HIV-1 resistance factor (HRF(+)) to study the inducible anti-HIV-1 responses mediated through novel soluble molecules. We found that exposure to the soluble products of HRF(+) cells activated CCCTC-binding factor (CTCF) mRNA expression in HIV-1 susceptible primary and transformed CD4(+) T cells and overlapped with their acquisition of transient resistance to virus. Conversely, the interference with the expression of CTCF gene in HRF(+) cells reversed the resistant phenotype and eliminated the biological potential of their cell culture supernatant to induce "HRF-like" activity in target cells. Band-shift analysis upon the nuclear fractions from HIV-1 resistant cells showed that CTCF protein bound to HIV-1 promoter and this binding prevented the formation of NF-kappaB/LTR complex. This evidence suggests that CTCF is an intracellular effector of HRF activity and that the acquisition of resistance to HIV-1 in CD4(+) T cells is a consequence of the prior activation of CTCF gene by the soluble entity secreted by HRF(+) cells.

BACKGROUND

The mechanisms contributing to hypoxic respiratory failure (HRF) in term infants are multifactorial. Recent evidence suggests a potential pathogenetic role for inflammation. Nitric oxide (NO), a pulmonary vasodilator, is inhibited by inflammatory mediators that are upregulated in the presence of placental inflammation.

OBJECTIVE

To examine the relationship between histological chorioamnionitis and/or funisitis, serum concentrations of inflammatory mediators and severity of HRF.

METHODS

Prospective observational study involving term neonates with HRF and normal controls. Blood samples were taken at birth from mixed cord blood, at 6 h and 30 h for cytokines and CRP, and at 72 h and 96 h for CRP. Placentas were examined for chorioamnionitis. The primary outcome was the administration of inhaled nitric oxide (iNO) therapy. Data were analysed using analysis of variance and chi(2) analysis.

RESULTS

32 neonates with hypoxic respiratory failure and 25 controls were enrolled. 14/32 (44%) neonates with HRF required iNO, 9/32 (28%) required high-frequency ventilation and 3/32 (9%) required ECMO; 2/32 (6%) died. Neonates with HRF had more than threefold higher cord levels of interleukin 8 (IL8) than the controls (p<0.05). At 6 h and 30 h, serum IL6, IL8 and CRP were>> or =2.2-fold higher in neonates who received iNO (p<0.003). 23/32 (72%) infants with HRF had evidence of histological chorioamnionitis and/or funisitis compared with 5/25 (20%) controls (p<0.001).

CONCLUSIONS

Severe HRF, as defined by the need for iNO, is associated with raised blood levels of proinflammatory mediators and increased occurrence of histological chorioamnionitis and funisitis, suggesting that inflammation contributes to the severity of hypoxic failure.

BACKGROUND

In healthy controls, haemodynamic refractory effects are observed with blood-oxygenation-level dependent (BOLD) functional MRI (fMRI): the haemodynamic response function (HRF) to the second stimulus in a pair of stimuli with short interstimulus interval (ISI) shows a decreased amplitude and an increased time-to-peak. We hypothesize that there may be interictal haemodynamic abnormalities in migraineurs.

METHODS

An event-related fMRI design with paired face stimuli and varying ISIs was used to measure interictal HRFs in the face recognition area of patients with migraine without aura (MwoA) and controls. Net responses to the second stimulus in a pair were calculated and averaged per participant. Several characterizing parameters of the net responses were quantified and examined within each group.

RESULTS

Refractory effects were not observed in our patient group. There are no changes in the net responses compared with the reference situation in patients, irrespective of the ISI, whereas in controls all HRF parameters are decreased or delayed for an ISI of 1 second.

CONCLUSIONS

This is the first fMRI study investigating the haemodynamic refractory effects in MwoA patients. Unlike in controls, these effects are not observed in migraineurs. Although currently unclear, it is tempting to speculate that this observation reflects the neurovascular correlate of lack of habituation measured with evoked potentials in migraineurs.

OBJECTIVE

To establish the effect of photodiode sensitivity on the DC (brightness) value and the resultant blood flow measurements of retina and rim tissue using a scanning laser Doppler flowmeter (SLDF).

METHODS

The sample consisted of one eye of each of 15 healthy subjects (mean age 27.8 +/- 6.1 years). Using the Heidelberg Retina Flowmeter (HRF), three 10-deg images of the superior temporal retina and three further images of the superior temporal rim were acquired for each of five DC bands: band 1: 30-70; band 2: 70-110; band 3: 110-150; band 4 150-190; band 5: 190-230. Retinal blood volume, flow and velocity were determined for each image using a 10 x 10 pixel square grid located at a predetermined location on the retina and rim for each subject. Following image acquisition, the DC values corresponding to each pre-assigned retinal or rim location were determined. The mean and standard deviation were determined for the blood flow parameters within each DC band for each subject in both locations. Analysis of variance was used to identify significant change in the data as a function of the DC value (P<0.05).

RESULTS

Analysis of variance revealed that retinal blood flow measures acquired within DC band 5 resulted in significantly lower measures of blood flow and velocity (P=0.035 and P=0.049 respectively) than at lower DC values. Band 5 values of flow, volume and velocity in the neuroretinal rim were also significantly low (P=0.016, P= 0.003 and P=0.026 respectively). Peak neuroretinal rim blood flow was recorded when the DC value was between 70 and 110. For blood flow measurement at the retina and neuroretinal rim the DC value should not exceed 190.

CONCLUSIONS

Photodiode sensitivity as indicated by the DC value affects measurements of ocular blood flow using the HRF.

CTL and NK cells produce a cytolytic pore-forming protein (perforin, cytolysin) localized in their cytoplasmic granules. These cytotoxic cells are resistant to killing mediated by other lymphocytes and by purified perforin. A membrane factor, known as homologous restriction factor (HRF), has been suggested to confer protection to different cell types against both C- and perforin-mediated lysis. The granules of human large granular lymphocytes have been reported to contain, in addition to perforin, a soluble HRF activity that can be eluted from anion-exchange columns at 115 mM NaCl. Here, we report that a soluble HRF activity is absent in the granules or the cytosol of murine CTL and human NK cells. Our data indicate that the inhibition attributed to HRF could be explained by exogenous EDTA added during granule fractionation. EDTA was shown to bind to Mono Q and to elute at 90 to 120 mM NaCl. A second perforin-inhibitory activity was also eluted from such a column. However, it was present in preparations obtained not only from CTL and NK cells, but also from some perforin-susceptible tumor cell lines, indicating that it has nonrestricted distribution and suggesting that it is probably irrelevant to the perforin-protection mechanism. Our results argue against a role for soluble granule HRF or other soluble factors in mediating resistance of cytotoxic lymphocytes against perforin-mediated lysis.

This research describes a new Bayesian spatiotemporal model to analyse block-design BOLD fMRI studies. In the temporal dimension, we parameterise the hemodynamic response function's (HRF) shape with a potential increase of signal and a subsequent exponential decay. In the spatial dimension, we use Gaussian Markov random fields (GMRF) priors on activation characteristics parameters (location and magnitude) that embody our prior knowledge that evoked responses are spatially contiguous and locally homogeneous. The result is a spatiotemporal model with a small number of parameters, all of them interpretable. Simulations from the model are performed in order to ascertain the performance of the sampling scheme and the ability of the posterior to estimate model parameters, as well as to check the model sensitivity to signal to noise ratio. Results are shown on synthetic data and on real data from a block-design fMRI experiment.

Histamine releasing factors (HRFs) have been demonstrated to be secreted by human lymphocytes and monocytes (alveolar macrophages); however, none has been purified to date. Because of the similarity of our HRF to the physical chemical properties of interleukin-1 (IL-1) and tumor necrosis factor (TNF), we have assessed the ability of preparations of IL-1 and TNF to cause basophil histamine release (HR). Human recombinant pro-IL-1 beta, recombinant mature IL-1, and, to a lesser extent, human recombinant TNF caused significant HR from a subpopulation of donor basophils. The pro-IL-1 beta elicited a dose response between 40 and 800 ng/ml; higher concentrations were inhibitory. Approximately 30% of subjects tested are responsive to either mature IL-1 or TNF. These share the same responder subset, but the magnitude of the TNF response is considerably less. A response to the pro-IL-1 was restricted to those subjects with prominent HR to anti-IgE; the response to mature IL-1 and TNF was unrelated to the response to anti-IgE. As in other functional assays, the pro-IL-1 is 50- to 100-fold less potent than mature IL-1, and unlike human HRF, it is highly unstable and rapidly loses activity. Mononuclear cell-derived HRF differs in physicochemical properties from IL-1 or TNF; nevertheless, it appears likely that a variety of cytokines may possess histamine-releasing capability.

Histamine-releasing factors (HRF) have received much attention over the last 17 years. With the availability of molecular biology techniques, cloned molecules have been identified as HRF. Examples include various interleukins, chemokines and the IgE-dependent HRF This human recombinant HRF (HrHRF) is a novel cytokine with no homology to any known molecule. Indeed, HrHRF acts as a complete secretagogue for basophils possessing a certain type of IgE, namely IgE+. Additionally, HrHRF can enhance histamine release from basophils possessing IgE-, basophils not normally responsive to HrHRF. Furthermore, HrHRF can activate eosinophils from allergic donors. This unique molecule may have a pivotal role in allergic diseases.

As elevated bronchoalveolar lavage (BAL) fluid histamine levels are noted in patients with pulmonary fibrosis (PF), we assayed BAL fluid from 16 patients with PF for the presence of a histamine releasing factor (HRF). HRF activity was assayed by measuring release of the preformed mast cell-derived mediators, histamine, or beta-hexosaminidase (beta-hex) from a purified population of IL-3 dependent mouse bone marrow derived mast cells (MBMMC) or human blood basophils. Mean BAL cell free histamine levels in the patients with PF was 1226 +/- 1349 pg/ml, whereas BAL histamine levels in a comparison group of six non-PF patients was 118 +/- 60 pg/ml. HRF was significantly elevated in BAL fluid of patients with PF (mean beta-hex release 24.5 +/- 12.9%; range 6.8 to 52.4%) compared to the non-PF group of patients (mean beta-hex release 7.9 +/- 7.7%; range 1.8 to 20.7%). The PF HRF not only degranulated MBMMC, but also induced the generation of the arachidonic acid metabolite leukotriene C4 from MBMMC (24.6 +/- 4.2 ng leukotriene C4/10(6) MBMMC). The PF HRF did not appear to be a cytokine previously identified in BAL fluid of patients with PF (i.e., platelet derived growth factor or insulin growth factor-1) or a human cytokine able to degranulate human basophils (i.e., IL-1, or granulocyte-macrophage-CSF) as these recombinant human cytokines did not induce MBMMC beta-hex release. Physicochemical characterization of the HRF revealed that it was relatively heat stable, pronase sensitive and on Sephadex G-75 and G-200 column chromatography had an apparent molecular mass of 30 to 50 kDa. The ability of PF BAL to induce beta-hex release from MBMMC was not dependent on IgE as unsensitized or lactic acid treated MBMMC release similar amounts of beta-hex compared to MBMMC sensitized with IgE. Thus, BAL fluid of patients with PF contains an HRF that induces beta-hex release from MBMMC via an IgE-independent mechanism. The presence of the HRF could explain elevated BAL histamine levels in patients with PF.

The objective was to compare the radial strength and expansile precision of self-expanding stents and balloon-expandable stents in a human cadaver bifurcation model. Seven different self-expanding (LUMINEXX, JOSTENT SelfX, JOSTENT SelfX hrf, Sinus-Repo, Sinus SuperFlex, Easy Wallstent, SMART) and four different balloon-expandable stent models (Palmaz, Sinus Stent, SAXX Medium, JOSTENT peripheral), each type 10 stents (total n = 110 stents) were implanted into the common iliac arteries of human cadaver corpses. The maximum stent diameter was 10 mm for all models. After stent implantation, the specimens were filled with silicone caoutchouc. After 24 h, the vascular walls including the stents were removed from the hardened casts. Diameters were taken and the weight of the cast cylinders was measured in air and in purified water to calculate the volume of the bodies (according to Archimedes Law) as a relative but precise degree for the radial strength of the implanted stents. The cylindrical casts of the self-expanding stents showed lower mean diameters (8.2 +/- 1.0 mm) and mean volumes (0.60 +/- 0.14 ml/cm) than in the balloon-expandable stent group (10.1 +/- 0.3 mm and 0.71 +/- 0.04 ml/cm, respectively; p < 0.01). The nominal maximum diameter of 10 mm was not achieved in any of the self-expanding stents, but this was achieved in more than 70% (29/40) of the balloon-expandable stent specimens (p < 0.05). The variation between achieved volumes was significantly larger in self-expanding (range: 0.23-0.78 ml/cm) than in balloon-expandable stents (range: 0.66-0.81 ml/cm; p < 0.05). Self-expanding stents presented considerably lower radial expansion force and lower degree of precision than balloon-expandable stents.

Homologous restriction factor (HRF) is a membrane protein of erythrocytes and leukocytes that inhibits the complement (C5b-9)-mediated lysis in a species-restricting manner. HRF has also been reported to inhibit perforin-mediated cytolysis and postulated to play a role in cytotoxic T lymphocyte (CTL) self-protection. We show that paroxysmal nocturnal hemoglobinuria (PNH) erythrocytes, lacking HRF, are no more sensitive to Ca2+-dependent human CTL-mediated lysis than normal erythrocytes. Furthermore, mouse and normal human erythrocytes, as well as PNH erythrocytes, are similarly lysed by isolated murine perforin-containing granules. We conclude that HRF does not inhibit perforin-mediated lysis and therefore is not likely to play a role in CTL self-protection.

A semi-parametric model for estimating hemodynamic response function (HRF) from multi-subject fMRI data is introduced within the context of the General Linear Model. The new model assumes that the HRFs for a fixed brain voxel under a given stimulus share the same unknown functional form across subjects, but differ in height, time to peak, and width. A nonparametric spline-smoothing method is developed to evaluate this common functional form, based on which subject-specific characteristics of the HRFs can be estimated. This semi-parametric model explicitly characterizes the common properties shared across subjects and is flexible in describing various brain hemodynamic activities across different regions and stimuli. In addition, the temporal differentiability of the employed spline basis enables an easy-to-compute way of evaluating latency and width differences in hemodynamic activity. The proposed method is applied to data collected as part of an ongoing study of socially mediated emotion regulation. Comparison with several existing methods is conducted through simulations and real data analysis.

Despite its potential advantages for fMRI analysis, fuzzy C-means (FCM) clustering suffers from limitations such as the need for a priori knowledge of the number of clusters, and unknown statistical significance and instability of the results. We propose a randomization-based method to control the false-positive rate and estimate statistical significance of the FCM results. Using this novel approach, we develop an fMRI activation detection method. The ability of the method in controlling the false-positive rate is shown by analysis of false positives in activation maps of resting-state fMRI data. Controlling the false-positive rate in FCM allows comparison of different fuzzy clustering methods, using different feature spaces, to other fMRI detection methods. In this article, using simulation and real fMRI data, we compare a novel feature space that takes the variability of the hemodynamic response function into account (HRF-based feature space) to the conventional cross-correlation analysis and FCM using the cross-correlation feature space. In both cases, the HRF-based feature space provides a greater sensitivity compared to the cross-correlation feature space and conventional cross-correlation analysis. Application of the proposed method to finger-tapping fMRI data, using HRF-based feature space, detected activation in sub-cortical regions, whereas both of the FCM with cross-correlation feature space and the conventional cross-correlation method failed to detect them.

The extraction and detection of specific responses from a large amount of background noise has been the subject of a considerable body of research in brain functional imaging, and more specifically in optical intrinsic signal imaging. Recent work by Kalatsky and Stryker (2003) showed that by combining different conditions and using periodic stimuli, recording times can be reduced. Spectral decomposition is then used to provide amplitude and phase information locked to the stimulus. A drawback of the above method is that by focusing only on a single harmonic, response information is limited. The shape of the hemodynamic response function (HRF) and the temporal variations in the neural responses cannot be assessed. In this work it is argued that additional information about neural responses can be gathered by using higher harmonics. Moving bars were used to generate visuotopic maps on large portions of the cat visual cortex. Up to four simultaneously bars moving repetitively across the visual field at different frequencies were used to sample the HRF in the Fourier domain. The HRF profile obtained with continuous stimulation was spatially homogeneous throughout the cortex and similar to the HRF profile obtained using episodic stimulation. Furthermore, by modeling the optical response as a convolution between HRF and neuronal responses, the ratio of the second harmonic to the first provided an estimation of the receptive field size. This was further validated by measuring spatial frequency selectivity. Therefore, the use of higher harmonics opens new avenues to estimate receptive field size from temporal signals.