As part of fMRI data analysis, the pyhrf package provides a set of tools for addressing the two main issues involved in intra-subject fMRI data analysis: (1) the localization of cerebral regions that elicit evoked activity and (2) the estimation of activation dynamics also known as Hemodynamic Response Function (HRF) recovery. To tackle these two problems, pyhrf implements the Joint Detection-Estimation framework (JDE) which recovers parcel-level HRFs and embeds an adaptive spatio-temporal regularization scheme of activation maps. With respect to the sole detection issue (1), the classical voxelwise GLM procedure is also available through nipy, whereas Finite Impulse Response (FIR) and temporally regularized FIR models are concerned with HRF estimation (2) and are specifically implemented in pyhrf. Several parcellation tools are also integrated such as spatial and functional clustering. Parcellations may be used for spatial averaging prior to FIR/RFIR analysis or to specify the spatial support of the HRF estimates in the JDE approach. These analysis procedures can be applied either to volume-based data sets or to data projected onto the cortical surface. For validation purpose, this package is shipped with artificial and real fMRI data sets, which are used in this paper to compare the outcome of the different available approaches. The artificial fMRI data generator is also described to illustrate how to simulate different activation configurations, HRF shapes or nuisance components. To cope with the high computational needs for inference, pyhrf handles distributing computing by exploiting cluster units as well as multi-core machines. Finally, a dedicated viewer is presented, which handles n-dimensional images and provides suitable features to explore whole brain hemodynamics (time series, maps, ROI mask overlay).

OBJECTIVE

To compare the macular capillary blood flow of patients with clinically significant diabetic macular oedema (DMO) with that of non-diabetic subjects and to determine the relation between blood flow and capillary leakage in patients with DMO.

METHODS

The sample comprised 45 non-diabetic subjects (mean age 59 years) and 18 type 2 patients with clinically significant DMO (mean age 60 years). Macular capillary blood flow measurements were acquired using the Heidelberg retina flowmeter (HRF) and a 10 degrees x2.5 degrees scan field centred on the fovea. Fluorescein angiography was undertaken on each of the diabetic patients after the completion of HRF measurements.

RESULTS

Temporal macular capillary blood flow was significantly lower for the patients with clinically significant DMO compared with age matched non-diabetic subjects (ANCOVA, p = 0.0011) while relative nasal-temporal asymmetry of macular capillary blood flow was significantly higher (p = 0.0125). Nasal-temporal asymmetry of macular capillary blood flow was significantly higher for the patients with DMO and capillary leakage within the scan area (two tailed t test, p = 0.0071). Macular capillary blood flow was always lower in areas of DMO and capillary leakage.

CONCLUSIONS

Capillary blood flow was reduced in areas of DMO and capillary leakage, suggesting the presence of a localised perturbation of capillary blood flow regulation.

Recent studies have demonstrated significant regional variability in the hemodynamic response function (HRF), highlighting the difficulty of correctly interpreting functional MRI (fMRI) data without proper modeling of the HRF. The focus of this study was to investigate the HRF variability within visual cortex. The HRF was estimated for a number of cortical visual areas by deconvolution of fMRI blood oxygenation level dependent (BOLD) responses to brief, large-field visual stimulation. Significant HRF variation was found across visual areas V1, V2, V3, V4, VO-1,2, V3AB, IPS-0,1,2,3, LO-1,2, and TO-1,2. Additionally, a subpopulation of voxels was identified that exhibited an impulse response waveform that was similar, but not identical, to an inverted version of the commonly described and modeled positive HRF. These voxels were found within the retinotopic confines of the stimulus and were intermixed with those showing positive responses. The spatial distribution and variability of these HRFs suggest a vascular origin for the inverted waveforms. We suggest that the polarity of the HRF is a separate factor that is independent of the suppressive or activating nature of the underlying neuronal activity. Correctly modeling the polarity of the HRF allows one to recover an estimate of the underlying neuronal activity rather than discard the responses from these voxels on the assumption that they are artifactual. We demonstrate this approach on phase-encoded retinotopic mapping data as an example of the benefits of accurately modeling the HRF during the analysis of fMRI data.

The tenth long-duration expedition crew is currently in residence aboard International Space Station (ISS), continuing a permanent human presence in space that began in October 2000. During that time, expedition crews have been operators and subjects for 18 Human Life Sciences investigations, to gain a better understanding of the effects of long-duration spaceflight on the crewmembers and of the environment in which they live. Investigations have been conducted to study: the radiation environment in the station as well as during extravehicular activity (EVA); bone demineralization and muscle deconditioning; changes in neuromuscular reflexes; muscle forces and postflight mobility; causes and possible treatment of postflight orthostatic intolerance; risk of developing kidney stones; changes in pulmonary function caused by long-duration flight as well as EVA; crew and crew-ground interactions; changes in immune function, and evaluation of imaging techniques. The experiment mix has included some conducted in flight aboard ISS as well as several which collected data only pre- and postflight. The conduct of these investigations has been facilitated by the Human Research Facility (HRF). HRF Rack 1 became the first research rack on ISS when it was installed in the US laboratory module Destiny in March 2001. The rack provides a core set of experiment hardware to support investigations, as well as power, data and commanding capability, and stowage. The second HRF rack, to complement the first with additional hardware and stowage capability, will be launched once Shuttle flights resume. Future years will see additional capability to conduct human research on ISS as International Partner modules and facility racks are added to ISS. Crew availability, both as a subject count and time, will remain a major challenge to maximizing the science return from the bioastronautics research program.

Human mononuclear cell-derived histamine-releasing factor (MNC-HRF) has m.w. of 29,000 and 23,000 and two charge species isoelectric at pH 6.9 and 7.3. Minor forms of HRF are also seen at m.w. of 12,000 to 15,000 and 60,000 to 80,000. In this manuscript we have further defined the response of human basophils to MNC-HRF in terms of atopic status of cell donors and the role of IgE antibody. We found that basophils of allergic persons, nonallergic controls, or donors who have positive skin tests but no symptoms, cannot be distinguished based upon responsiveness to HRF. Further, the response of basophils that have been desensitized to anti-IgE is retained when they are subsequently stimulated with HRF derived from human MNC. Thus an interaction with cell-surface IgE to cause histamine release is not evident. Nevertheless, one of two IgE myeloma proteins tested were capable of binding HRF and such binding could be utilized as a purification step. We conclude that MNC-HRF is heterogeneous in terms of size, charge, and affinity for a subpopulation of IgE. Histamine release is more prominent in atopic individuals but does not appear to require an interaction with IgE.

BACKGROUND

The purpose of the present study was (1) to test the accuracy of a small-volume cone-beam computed tomographic (CBCT) device in detecting horizontal root fractures (HRFs) in teeth with and without an intracanal metallic post (IMP) and (2) to investigate the use of 2 different acquisition protocols of a CBCT device for HRF diagnosis.

METHODS

Forty endodontically treated teeth with and without an IMP were examined using PreXion 3D CBCT scanner (Terarecon, San Mateo, CA) with a 5-cm high and 5-cm diameter cylinder at 0.10-mm voxel reconstruction. Two observers analyzed the samples to determine the presence and location of HRFs.

RESULTS

Sensitivity values ranged from 0.40-0.80. The most favorable results were found for the samples with no IMP observed using the protocol of a higher number of x-ray projections (0.70-0.80). Accuracy in the groups with an IMP ranged from 75%-90% in the 1024 x-ray projection protocol (HI-HI group) versus 70%-85% for the same samples examined in the 512 x-ray projection protocol (HI-STD group). Intraobserver agreement ranged from relevant to perfect concordance for both protocols (HI-HI = Kappa: 0.60-1.00 and HI-STD = Kappa: 0.55-0.89). Interobserver agreement ranged from moderate to perfect concordance for both protocols (HI-HI = Kappa: 0.79-0.89 and HI-STD = Kappa: 0.42-0.76).

CONCLUSIONS

Even though there are statistically significant differences for the protocol with the higher number of x-ray projections, we found high accuracy, sensitivity, sensibility, and intra- and interobserver agreement in detecting HRFs for both Prexion 3D protocols.

Global protein synthesis arrest occurs in Autographa californica nucleopolyhedrovirus (AcNPV)-infected Ld652Y cells at late times postinfection (p.i.). A Lymantria dispar nucleopolyhedrovirus gene, hrf-1, precludes this protein synthesis arrest. We used in vitro translation assays to characterize the translation defect. Cell-free lysates prepared from uninfected Ld652Y cells, AcNPV-infected cells harvested at early times p.i., and cells infected with vAchrf-1, a recombinant AcNPV bearing hrf-1, all supported translation. Lysates prepared from AcNPV-infected Ld652Y cells at late times p.i. did not support translation, but activity was restored by adding small RNA species from mock-, vAchrf-1- (24 or 48 h p.i.), and AcNPV- (6 h p.i. ) infected cells. Small RNA species (24 and 48 h p.i.) from AcNPV-infected cells did not rescue translation. Assays of RNA species further fractionated by ion exchange chromatography demonstrated that tRNA rescued translation. Although specific defective tRNA species were not revealed by comparative two-dimensional gel analysis, analysis of (32)P-labeled tRNAs showed a reduction in de novo synthesis of small RNA isolated from AcNPV-infected cells compared with mock- and vAchrf-1-infected cells. This study suggests a mechanism of translation arrest involving defective or depleted tRNA species in AcNPV-infected Ld652Y cells.

Little is known about the neural correlates of expository text comprehension. In this study, we sought to identify neural networks underlying expository text comprehension, how those networks change over the course of comprehension, and whether information central to the overall meaning of the text is functionally distinct from peripheral information. Seventeen adult subjects read expository passages while being scanned using functional magnetic resonance imaging (fMRI). By convolving phrase onsets with the hemodynamic response function (HRF), we were able to identify regions that increase and decrease in activation over the course of passage comprehension. We found that expository text comprehension relies on the co-activation of the semantic control network and regions in the posterior midline previously associated with mental model updating and integration [posterior cingulate cortex (PCC) and precuneus (PCU)]. When compared to single word comprehension, left PCC and left Angular Gyrus (AG) were activated only for discourse-level comprehension. Over the course of comprehension, reliance on the same regions in the semantic control network increased, while a parietal region associated with attention [intraparietal sulcus (IPS)] decreased. These results parallel previous findings in narrative comprehension that the initial stages of mental model building require greater visuospatial attention processes, while maintenance of the model increasingly relies on semantic integration regions. Additionally, we used an event-related analysis to examine phrases central to the text's overall meaning vs. peripheral phrases. It was found that central ideas are functionally distinct from peripheral ideas, showing greater activation in the PCC and PCU, while over the course of passage comprehension, central and peripheral ideas increasingly recruit different parts of the semantic control network. The finding that central information elicits greater response in mental model updating regions than peripheral ideas supports previous behavioral models on the cognitive importance of distinguishing textual centrality.

OBJECTIVE

In the last twenty years, there has been increasing evidence that Motor Competence (MC) is vital for developing an active and healthy lifestyle. This study analyses the associations between motor competence and its components, with health-related fitness (HRF).

METHODS

A random sample of 546 children (278 males, mean = 10.77 years) divided into four age groups (7-8; 9-10; 11-12; 13-14 years old) was evaluated. A quantitative MC instrument (evaluating stability, locomotor and manipulative skills), a maximal multistage 20-m shuttle-run test and the handgrip test, height and BMI were used in the analyses. Pearson correlations and standard regression modelling were performed to explore the associations between variables.

RESULTS

Moderate to strong significant correlations (0.49 < r < 0.73) were found between MC and HRF, for both sexes, and correlation values were stable across the age groups. The MC model explained 74% of the HRF variance, with the locomotor component being the highest predictor for the entire sample (β = .302; p < .001). Gender-related differences were found when boys and girls were analysed at each age group. Locomotor MC for girls was the most consistent significant predictor of HRF across all age groups (0.47 < β < 0.65; all p≤.001). For boys, significant predictors were locomotor and manipulative MC (0.21 < β < 0.49; all p < .05) in the two younger age groups (7-8 and 9-10 years) and stability (0.50 < β < 0.54; all p≤.001) for the older two age groups (11-12 and 13-14 years).

CONCLUSIONS

These results support the idea that: (1) the relationship between overall MC and HRF is strong and stable across childhood and early adolescence; (2) when accounting for the different MC components, boys and girls show different relationship patterns with HFR across age.

Blood oxygenation level-dependent (BOLD) signal time courses in functional magnetic resonance imaging are estimated within the framework of general linear modeling by convolving an input function, that represents neural activity, with a canonical hemodynamic response function (HRF). Here we investigate the performance of different neural input functions and latency-optimized HRFs for modeling BOLD signals in response to vibrotactile somatosensory stimuli of variable durations (0.5, 1, 4, 7 s) in 14 young, healthy adults who were required to make button press responses at each stimulus cessation. Informed by electrophysiology and the behavioral task, three nested models with an increasing number of parameters were considered: a boxcar; boxcar and offset transient; and onset transient, boxcar and offset transient (TBT). The TBT model provided the best fit of the group-averaged BOLD time courses based on χ(2) and F statistics. Only the TBT model was capable of fitting the bimodal shape of the BOLD response to the 7-s stimulus and the relative peak amplitudes for all stimulus lengths in key somatosensory and motor areas. This suggests that the TBT model provides a more comprehensive description of brain sensorimotor responses in this experiment than provided by the simple boxcar model. Work comparing the activation maps obtained with the TBT model with magnetoencephalography data is under way.

Human mononuclear cells (MNC) secrete histamine-releasing factor(s) (HRF) when cultured in vitro. HRF induces the release of histamine and other mediators from basophils and mast cells. We have shown that MNC also produced a histamine release inhibitory factor (HRIF), and that the synthesis is augmented by culture with physiologic concentrations of histamine (10(-10) to 10(-6) M) and by the mitogen concanavalin A (Con A). HRIF does not affect release initiated by other secretagogues such as allergen, anti-IgE, C5a, Con A, and phorbol myristate acetate. HRIF requires a preincubation with the cells for 5-10 min for maximal inhibition, and this effect is not abolished by washing the cells after the preincubation. The biological activity of HRIF is protease-sensitive, neuraminidase-resistant, and relatively heat-stable. HRIF can be distinguished from HRF by a lower apparent molecular mass (8,000-10,000 D).

BACKGROUND

We present a simple, data-driven method to extract haemodynamic response functions (HRF) from functional magnetic resonance imaging (fMRI) time series, based on the Fourier-wavelet regularised deconvolution (ForWaRD) technique. HRF data are required for many fMRI applications, such as defining region-specific HRFs, effciently representing a general HRF, or comparing subject-specific HRFs.

RESULTS

ForWaRD is applied to fMRI time signals, after removing low-frequency trends by a wavelet-based method, and the output of ForWaRD is a time series of volumes, containing the HRF in each voxel. Compared to more complex methods, this extraction algorithm requires few assumptions (separability of signal and noise in the frequency and wavelet domains and the general linear model) and it is fast (HRF extraction from a single fMRI data set takes about the same time as spatial resampling). The extraction method is tested on simulated event-related activation signals, contaminated with noise from a time series of real MRI images. An application for HRF data is demonstrated in a simple event-related experiment: data are extracted from a region with significant effects of interest in a first time series. A continuous-time HRF is obtained by fitting a nonlinear function to the discrete HRF coeffcients, and is then used to analyse a later time series.

CONCLUSIONS

With the parameters used in this paper, the extraction method presented here is very robust to changes in signal properties. Comparison of analyses with fitted HRFs and with a canonical HRF shows that a subject-specific, regional HRF significantly improves detection power. Sensitivity and specificity increase not only in the region from which the HRFs are extracted, but also in other regions of interest.

Histamine releasing factors (HRF) are a group of cytokines that cause degranulation of basophils and mast cells. Recently we have described a histamine release inhibitory factor (HRIF) that inhibits HRF-induced histamine release from basophils and mast cells. The objective of this study was to investigate the presence of these cytokines in bronchoalveolar lavage (BAL) fluid from normal subjects. We found that BAL fluids from 12 to 17 volunteers contained a dialyzable (molecular weight cutoff 3500) factor that inhibited basophil histamine release by HRF, anti-IgE, concanavalin A, and N-formyl-methionyl-leucyl-phenylalanine (FMLP). In addition, BAL fluids from 83% of the tested donors contained a nondialyzable inhibitor that blocked HRF-induced histamine release from basophils. The molecular weight of this inhibitor was estimated to be 20 to 30 and 8 to 10 kD by Sephadex G-50 chromatography and TSK 2000 size-exclusion HPLC. None of the unconcentrated BAL fluids showed any HRF activity on initial screening using basophils from allergic subjects. However, when the BAL fluids were concentrated, all BAL samples that were tested (N = 10) demonstrated significant HRF activity. The molecular weight of BAL HRF has been estimated to be in the range of 15 to 25 kD by size-exclusion HPLC, similar to the HRF synthesized by mononuclear cells. Thus we have demonstrated the presence of both HRF and HRIF in the BAL fluids. We speculate that these cytokines may be involved in the local regulation of basophil and mast cell activation.

Agents which increase or mimic intracellular cyclic 3',3'-adenosine monophosphate (cAMP) - theophylline dibutyryl cAMP (DBcAMP) and isoprenaline (in the presence of theophylline) - all produced pronounced inhibition of histamine release from human basophils, thus suggesting a regulatory role for the cAMP system. The effect of the flavonoids , quercetin and taxifolin , and the structurally-related cromone disodium cromoglycate (DSCG) was also studied. Only quercetin was effective in inhibiting histamine release. This is similar to the situation in IgE-mediated release. The microtubule stabilizer, deuterium oxide (D2O), at a concentration of 44% caused up to three-fold increase in release. This supports the belief that histamine release by this histamine-releasing factor ( HRF ) is a secretory process. Indomethacin and 5,8,11,14-eicosatetraynoic acid (ETYA), which are modulators of arachidonic acid metabolism, produced little or no inhibition of histamine release by HRF , thus suggesting that the release is largely independent of the arachidonate system, probably unlike IgE-mediated release.

Spoilage of heat processed food and beverage by heat resistant fungi (HRF) is a major problem for food industry in many countries. Neosartorya fischeri is the leading source of spoilage in thermally processed products. Its resistance to heat processing and toxigenicity makes studies about Neosartorya fischeri metabolism and chemical sensitivity essential. In this study chemical sensitivity of two environmental Neosartorya fischeri isolates were compared. One was isolated from canned apples in 1923 (DSM3700), the other from thermal processed strawberry product in 2012 (KC179765), used as long-stored and fresh isolate, respectively. The study was conducted using Biolog Phenotype MicroArray platforms of chemical sensitivity panel and traditional hole-plate method. The study allowed for obtaining data about Neosartorya fischeri growth inhibitors. The fresh isolate appeared to be much more resistant to chemical agents than the long-stored isolate. Based on phenotype microarray assay nitrogen compounds, toxic cations and membrane function compounds were the most effective in growth inhibition of N. fischeri isolates. According to the study zaragozic acid A, thallium(I) acetate and sodium selenate were potent and promising N. fischeri oriented fungicides which was confirmed by both chemical sensitivity microplates panel and traditional hole-plate methods.

Pregabalin increased the incidence of hemangiosarcomas in carcinogenicity studies of 2-year mice but was not tumorigenic in rats. Serum bicarbonate increased within 24 h of pregabalin administration in mice and rats. Rats compensated appropriately, but mice developed metabolic alkalosis and increased blood pH. Local tissue hypoxia and increased endothelial cell proliferation were also confirmed in mice alone. The combination of hypoxia and sustained increases in endothelial cell proliferation, angiogenic growth factors, dysregulated erythropoiesis, and macrophage activation is proposed as the key event in the mode of action (MOA) for hemangiosarcoma formation. Hemangiosarcomas occur spontaneously in untreated control mice but occur only rarely in humans. The International Programme on Chemical Safety and International Life Sciences Institute developed a Human Relevance Framework (HRF) analysis whereby presence or absence of key events can be used to assess human relevance. The HRF combines the MOA with an assessment of biologic plausibility in humans to assess human relevance. This manuscript compares the proposed MOA with Hill criteria, a component of the HRF, for strength, consistency, specificity, temporality, and dose response, with an assessment of key biomarkers in humans, species differences in response to disease conditions, and spontaneous incidence of hemangiosarcoma to evaluate human relevance. Lack of key biomarker events in the MOA in rats, monkeys, and humans supports a species-specific process and demonstrates that the tumor findings in mice are not relevant to humans at the clinical dose of pregabalin. Based on this collective dataset, clinical use of pregabalin would not pose an increased risk for hemangiosarcoma to humans.

OBJECTIVE

To evaluate the effect of 0.5% timolol maleate on the capillary circulation of the anterior optic nerve head in patients with primary open-angle glaucoma and to compare the results with those obtained in a healthy control group.

METHODS

Twelve patients with nonprogressive glaucoma and 12 age- and sex-matched healthy volunteers were included in this prospective study. Optic nerve head perfusion was examined by the Heidelberg Retina Flowmeter (HRF) in both groups. A 3-week washout period preceded the baseline measurement in the glaucoma group, and ONH blood flow was assessed again after 3 weeks of bilateral topical timolol treatment and 2 hours after timolol application.

RESULTS

Intraocular pressure decreased significantly with timolol (P < 0.001). The HRF flow values for patients with glaucoma were comparable to those for a control group at baseline (P = 0.25), 3 weeks after timolol therapy (P = 0.09), and 2 hours after timolol instillation (P = 0.15). The glaucoma group showed no statistically significant change in the HRF parameter flow as compared with baseline, either after 3 weeks of timolol treatment or 2 hours after timolol instillation (P = 0.40). The heart rate and arterial systolic and diastolic blood pressure values showed no alteration after timolol therapy.

CONCLUSIONS

Patients with nonprogressive glaucoma seem not to have an altered optic nerve blood flow as assessed by the HRF, and timolol treatment does not seem to alter the latter blood flow parameter in such patients.

OBJECTIVE

Blood flow measures acquired using the scanning laser Doppler flowmeter (SLDF) are known to be highly susceptible to spatial and temporal variations of physiological origin. The purpose of this study was to evaluate a local search strategy intended to overcome these intrinsic variations, thereby improving the detection of blood flow defects resulting from glaucoma.

METHODS

The sample consisted of one eye of each of 15 glaucoma patients (aged 69.1 (SD 6.6) years) and 15 normal subjects (aged 65.2 (13.7) years). Three 10 degree images of the superior temporal retina and three images of the superior temporal rim were acquired using the Heidelberg retina flowmeter (HRF). Standard analysis was performed using a 10 x 10 pixel frame. For the search strategy the same frame was located within a 15 x 15 pixel window and manually repositioned in order to identify the highest and lowest local values of blood flow. Student's paired t test was used to identify differences between groups for the two methods (p<0.05).

RESULTS

The standard strategy revealed no significant differences in blood flow measures between the subjects at either the retina or neuroretinal rim. With the search strategy there was also no difference in blood flow measures at the retina. At the neuroretinal rim, the search strategy demonstrated that the highest measured blood flow, volume, and velocity values were significantly lower for the glaucoma patients (p = 0.002, 0.02, and 0.002 respectively) while comparison of the lowest flow values showed that glaucoma patients had lower blood flow and velocity only (p = 0.023 and 0.021 respectively).

CONCLUSIONS

Glaucoma patients exhibit reduced ocular blood flow at the neuroretinal rim, which seems to affect high velocity flow more profoundly than low velocity flow. When analysing perfusion images a local search strategy is recommend to identify the highest local blood flow values in order to optimise the ability to differentiate between subject groups.

OBJECTIVE

To study the effect of topical brinzolamide on retinal capillary blood flow by the Heidelberg Retina Flowmeter (HRF) in patients with glaucoma.

METHODS

Twenty patients with glaucoma were consecutively recruited. One eye for each patient was randomly selected. Patients were classified as glaucomatous if they had an abnormal visual field and/or an abnormal optic nerve head with an intraocular pressure (IOP) greater than 21 mm Hg without any treatment. After an eye examination, baseline retinal blood flow measurements were made with confocal scanning laser Doppler flowmetry. Blood flow and IOP measurements were then repeated after 1 month of treatment. Blood flow measurements were analyzed by using an automatic full-field perfusion image analysis (AFFPIA) program. The blood flow was calculated in the superior and inferior part of the optic disk. In each area, the blood flow was calculated as temporal area, the nasal area and the rim area as for software AFFPIA.

RESULTS

The mean age of the patients was 56 +/- 7 (mean +/- standard deviation) years. The mean IOP before treatment was 23.7 +/- 1.5 mm Hg while the mean IOP after 4 weeks of treatment was 19.1 +/- 2.2 mm Hg. This difference was statistically significant (p < 0.01). Significant (p < 0.05) increases in retinal blood flow were found for the temporal and nasal areas between baseline and 1 month after the treatment. No difference was found between superior and inferior sectors.

CONCLUSIONS

Topical brinzolamide reduced the IOP significantly and apparently improved retinal blood flow as measured by the HRF.

We have previously shown that the coral cell signal, host release factor (HRF) from the scleractinian coral Plesiastrea versipora (Lamarck) stimulates the release of glycerol from its symbiotic dinoflagellate, Symbiodinium sp. Glycerol is a precursor for algal triacylglycerol (TG) and starch, and we have previously observed that HRF reduces the amount of newly synthesized TG in Symbiodinium sp. We have now examined the effect of P. versipora HRF on starch synthesis in isolated Symbiodinium. HRF had no effect on starch synthesis after 2 h photosynthesis (16.3+/-3.0 microg starch per 10(6) algae) compared with algae in seawater (13.9+/-1.2 microg starch per 10(6) algae). However, after 4 h incubation in HRF, there was a reduction (0-76%), in the amount of newly synthesized starch which was correlated with the amount of HRF (10-76 microg/ml). Reducing algal synthesis of both TG and starch in parallel with stimulating glycerol release may provide a mechanism to regulate the population density of intracellular symbiotic algae while still ensuring the transfer of photosynthetically fixed carbon to the animal host in the form of glycerol.

In the past, we showed that local infection of tobacco leaves with either tobacco mosaic virus or oilseed rape mosaic virus (ORMV) resulted in a systemic increase in the homologous recombination frequency (HRF). Later on, we showed that a similar phenomenon occurs in Arabidopsis thaliana plants infected with ORMV. Here, we tested whether the time of removing the infected leaves as well as viral titer have any effect on the degree of changes in HRF in systemic tissues. An increase in HRF in systemic non-infected tissues was more pronounced when the infected leaves were detached from the infected plants at 60-96 h post-infection, rather than at earlier time. Next, we found that exposure to higher concentrations of inoculum was much more efficient in triggering an increase in HRF than exposure to lower concentrations. Finally, we showed that older plants exhibited a higher increase in HRF than younger plants. We found that an increase in genome instability in systemic tissues of locally infected plants depends on plant age, the concentration of initial inoculums and the time of viral replication.

The objectives were to evaluate factors affecting reproductive performance of dairy heifers. Holstein heifers (6389) were housed in a feed lot located in Parma, ID. Each week heifers weighing>> or =290 kg were initiated in the reproductive program, which consisted of one injection of PGF(2alpha) and AI on detection of estrus. Heifers not inseminated by 11 days after the initiation of the breeding program received a second injection of PGF(2alpha). Pregnancy was diagnosed at 40+/-3 and 90+/-3 days after AI. Average daily minimum temperature (ADMnT), average daily maximum temperature (ADMxT), and average daily rainfall (ARF) were recorded between 15 days prior to and 15 days after the day of AI or the day of initiation of the breeding program. Exposure to air temperature was classified as: cold stress (CS=ADMnT< or =4 degrees C), no stress (NS=ADMnT>4 degrees C and ADMxT<29 degrees C), and heat stress (HS=ADMxT> or =29 degrees C). Exposure to rainfall was classified as above (HRF) or below (LRF) the mean for the period in question. Heifers were classified according to body weight at initiation of the breeding program as thin (TH<340 kg); moderate (MD=340-365 kg); and heavy (HY>365 kg). Service sire was associated with conception rate at 40 and 90 days after first AI. Although exposure to air temperature was not correlated with conception rate at 40 days after first AI, heifers exposed to cold stress had smaller conception rates at 90 days after first AI because they were more likely to lose pregnancy between 40 and 90 days of gestation. The proportion of heifers inseminated after initiation of the breeding program was correlated with body weight and exposure to cold stress. Exposure to cold stress was also correlated with the proportion of heifers conceiving within 11 and 22 days after initiation of the breeding program. From this study a correlation was established between body weight and rate of insemination and between the exposure to cold stress and reproductive efficiency of Holstein heifers.

OBJECTIVE

Shear loading rates (LR) have not been investigated in runners with a mid- or forefoot strike (FFS) versus rearfoot strike (RFS). The purpose of this study was to compare three-dimensional ground reaction forces (GRF) and LR during impact in habitual rearfoot strikers (hRF) and habitual forefoot strikers (hFF) strikers.

METHODS

Thirty competitive runners performed 10 overground running trials with both foot strike styles. Peak three-dimensional and resultant GRF and instantaneous LR during impact were compared.

RESULTS

Vertical LR significantly decreased for hRF using an FFS (RFS = 148 ± 36 body weight [BW]·s(-1), FFS = 98 ± 31 BW·s(-1)) but was similar for hFF running with either foot strike (FFS = 136 ± 35 BW·s(-1), RFS = 135 ± 28 BW·s(-1)). Posterior impact forces were present during FFS but not during RFS, and posterior LR was significantly greater for both groups during FFS (-58 ± 17 vs -19 ± 6 BW·s(-1)). Medial impact forces were also present during FFS but not during RFS, and medial LR was significantly larger for both groups during FFS (-21 ± 7 vs -6 ± 6 BW·s(-1)). Interestingly, hFF had greater impact peaks and LR in all directions compared with hRF during FFS. This may be explained by hFF using a smaller strike index (hFF = 62% ± 9%, hRF = 67% ± 9%; P = 0.02), which was significantly inversely related to vertical LR and impact peak.

CONCLUSIONS

Peak resultant and vertical LR are not ubiquitously lower when using a shod FFS versus RFS despite an absence of resultant and vertical impact peaks. Furthermore, there were impact peaks in the posterior and medial directions, leading also to greater LR in these directions during FFS. Therefore, transitioning from RFS to FFS in traditional running shoes may not offer long-term protection against impact-related running injuries because hFF running with an FFS demonstrated many GRF and LR similar to or greater than RFS.