BACKGROUND

Most patients with chronic idiopathic urticaria (CIU) show cutaneous reactivity to intradermal injection of autologous serum. In some cases this reactivity is associated with the presence of autoantibodies directed against IgE or IgE receptors expressed on mast cells, whereas in others no autoimmune mechanisms can be documented.

OBJECTIVE

The aims of this study were to compare the cutaneous reactivity to serum and plasma samples in a series of patients with active CIU and to address the mechanisms of the inhibitory effect exerted by heparin on the cutaneous responsiveness to the histamine-releasing factors (HRFs) present in CIU serum.

METHODS

Fourteen patients with CIU were injected intradermally with autologous serum, plasma (anticoagulated by either heparin or EDTA), or serum samples to which heparin had been added. The effects of heparin injection on cutaneous responsiveness to allergens was tested in 5 atopic patients. Moreover, in a set of experiments sera were also adsorbed with Sepharose-conjugated heparin.

RESULTS

All the patients had positive cutaneous reactions to autologous serum injection. When heparinized plasma was injected, negative reactions were observed in 12 of 14 patients, and a sizable reduction in the wheal-and-flare reactions was recorded in the remaining 2. Compared with results obtained with serum, no substantial change was observed in 6 of 8 patients injected with EDTA-anticoagulated plasma. When heparin was added to serum, abrogation of skin reactivity was seen; nonetheless, no change in the cutaneous response to allergens was associated with locally administered heparin in 5 atopic patients with no history of CIU. Finally, adsorption of CIU sera with solid-phase heparin abrogated the ability to induce cutaneous reactions in 5 of 7 patients, whereas in the remaining 2 a sizable reduction was observed.

CONCLUSIONS

These data indicate that heparin is able to profoundly inhibit the cutaneous response to HRFs present in the sera of patients with CIU. Although the precise level of action of this heparin-mediated effect is unclear from present data, preliminary evidence seems to indicate that heparin could directly interfere with HRFs present in CIU sera.

Protein footprinting mediated by mass spectrometry has evolved over the last 30 years from proof of concept to commonplace biophysics tool, with unique capabilities for assessing structure and dynamics of purified proteins in physiological states in solution. This review outlines the history and current capabilities of two major methods of protein footprinting: reversible hydrogen-deuterium exchange (HDX) and hydroxyl radical footprinting (HRF), an irreversible covalent labeling approach. Technological advances in both approaches now permit high-resolution assessments of protein structure including secondary and tertiary structure stability mediated by backbone interactions (measured via HDX) and solvent accessibility of side chains (measured via HRF). Applications across many academic fields and in biotechnology drug development are illustrated including: detection of protein interfaces, identification of ligand/drug binding sites, and monitoring dynamics of protein conformational changes along with future prospects for advancement of protein footprinting in structural biology and biophysics research.

Electroencephalography (EEG) data simultaneously acquired with functional magnetic resonance imaging (fMRI) data are preprocessed to remove gradient artifacts (GAs) and ballistocardiographic artifacts (BCAs). Nonetheless, these data, especially in the gamma frequency range, can be contaminated by residual artifacts produced by mechanical vibrations in the MRI system, in particular the cryogenic pump that compresses and transports the helium that chills the magnet (the helium-pump). However, few options are available for the removal of helium-pump artifacts. In this study, we propose a recursive approach of EEG-segment-based principal component analysis (rsPCA) that enables the removal of these helium-pump artifacts. Using the rsPCA method, feature vectors representing helium-pump artifacts were successfully extracted as eigenvectors, and the reconstructed signals of the feature vectors were subsequently removed. A test using simultaneous EEG-fMRI data acquired from left-hand (LH) and right-hand (RH) clenching tasks performed by volunteers found that the proposed rsPCA method substantially reduced helium-pump artifacts in the EEG data and significantly enhanced task-related gamma band activity levels (p=0.0038 and 0.0363 for LH and RH tasks, respectively) in EEG data that have had GAs and BCAs removed. The spatial patterns of the fMRI data were estimated using a hemodynamic response function (HRF) modeled from the estimated gamma band activity in a general linear model (GLM) framework. Active voxel clusters were identified in the post-/pre-central gyri of motor area, only from the rsPCA method (uncorrected p<0.001 for both LH/RH tasks). In addition, the superior temporal pole areas were consistently observed (uncorrected p<0.001 for the LH task and uncorrected p<0.05 for the RH task) in the spatial patterns of the HRF model for gamma band activity when the task paradigm and movement were also included in the GLM.

Nostoc punctiforme is a filamentous cyanobacterium which forms nitrogen-fixing symbioses with several different plants and fungi. Establishment of these symbioses requires the formation of motile hormogonium filaments. Once infected, the plant partner is thought to supply a hormogonium-repressing factor (HRF) to maintain the cyanobacteria in a vegetative, nitrogen-fixing state. Evidence implies that sucrose may serve as a HRF. Here, we tested the effects of sucralose, a non-metabolizable sucrose analog, on hormogonium differentiation. Sucralose inhibited hormogonium differentiation at a concentration approximately one-tenth that of sucrose. This result implies that: (1) sucrose, not a sucrose catabolite, is perceived by the cell and (2) inhibition is not due to a more general osmolarity-dependent effect. Additionally, both sucrose and sucralose induced the accrual of a polysaccharide sheath which bound specifically to the lectin ConA, indicating the presence of α-D-mannose and/or α-D-glucose. A ConA-specific polysaccharide was also found to be expressed in N. punctiforme colonies from tissue sections of the symbiotically grown hornwort Anthoceros punctatus. These findings imply that plant-derived sucrose or sucrose analogs may have multiple effects on N. punctiforme, including both repression of hormogonia and the induction of a polysaccharide sheath that may be essential to establish and maintain the symbiotic state.

Physical activity (PA) decreases with age. The school transition is noted for significant changes in PA behaviour. Motor competence (MC), health-related fitness (HRF), and perceived competence (PC) are generally positively associated with PA. The aim of this study was to examine longitudinal cross-lagged relationships between PA, MC, HRF, and PC across the school transition from final year of primary school to first year of second-level school in Irish youth. PA (accelerometery), object-control and locomotor MC (TGMD-III), PC (perceived athletic competence subscale of the Self-Perception Profile for Adolescents), and HRF (20 m shuttle run, horizontal jump, vertical jump, push-ups, curl-ups) were measured in final year of primary school (6th class) and first year of second-level school (1st year). In the sixth class, 261 participants (53% female; mean age 12.22 ± 0.48 years) were tested. In first year, 291 participants (48% female; mean age: 13.20 ± 0.39 years) were tested. In total, 220 participants were involved in the study at both timepoints. Cross-lagged regression in AMOS23, using full information maximum likelihood estimation, was conducted to test reciprocal and predictive pathways between variables. The full cross-lagged model showed acceptable fit (χ² = 69.12, df = 8, p < 0.01, NFI = 0.93, CFI = 0.94). HRF was the strongest predictor of future PA (β = 0.353), and also predicted PC (β = 0.336) and MC (β = 0.163). Object-control MC predicted future PA (β = 0.192). Reciprocal relationships existed between object-control MC and PA, and between object-control MC and PC. HRF was the strongest predictor of PA. Object-control MC also predicted PA. PA promotion strategies should target the development of HRF and object-control MC in primary school to reduce the decline in PA frequently observed after the school transition.

Neonatal hypoxemic respiratory failure (HRF), a deficiency of oxygenation associated with insufficient ventilation, can occur due to a variety of etiologies. HRF can result when pulmonary vascular resistance (PVR) fails to decrease at birth, leading to persistent pulmonary hypertension of newborn (PPHN), or as a result of various lung disorders including congenital abnormalities such as diaphragmatic hernia, and disorders of transition such as respiratory distress syndrome, transient tachypnea of newborn and perinatal asphyxia. PVR changes throughout fetal life, evident by the dynamic changes in pulmonary blood flow at different gestational ages. Pulmonary vascular transition at birth requires an interplay between multiple vasoactive mediators such as nitric oxide, which can be potentially inactivated by superoxide anions. Superoxide anions have a key role in the pathophysiology of HRF. Oxygen (O2) therapy, used in newborns long before our knowledge of the complex nature of HRF and PPHN, has continued to evolve. Over time has come the discovery that too much O2 can be toxic. Recommendations on the optimal inspired O2 levels to initiate resuscitation in term newborns have ranged from 100% (pre 1998) to the currently recommended use of room air (21%). Questions remain about the most effective levels, particularly in preterm and low birth weight newborns. Attaining the appropriate balance between hypoxemia and hyperoxemia, and targeting treatments to the pathophysiology of HRF in each individual newborn are critical factors in the development of improved therapies to optimize outcomes.

The argasid tick Ornithodoros moubata is the main vector of human relapsing fever (HRF) and African swine fever (ASF) in Africa. Salivary proteins are part of the host-tick interface and play vital roles in the tick feeding process and the host infection by tick-borne pathogens; they represent interesting targets for immune interventions aimed at tick control. The present work describes the transcriptome profile of salivary glands of O. moubata and assesses the gene expression dynamics along the trophogonic cycle using Illumina sequencing. De novo transcriptome assembling resulted in 71,194 transcript clusters and 41,011 annotated transcripts, which represent 57.6% of the annotation success. Most salivary gene expression takes place during the first 7 days after feeding (6,287 upregulated transcripts), while a minority of genes (203 upregulated transcripts) are differentially expressed between 7 and 14 days after feeding. The functional protein groups more abundantly overrepresented after blood feeding were lipocalins, proteases (especially metalloproteases), protease inhibitors including the Kunitz/BPTI-family, proteins with phospholipase A2 activity, acid tail proteins, basic tail proteins, vitellogenins, the 7DB family and proteins involved in tick immunity and defence. The complexity and functional redundancy observed in the sialotranscriptome of O. moubata are comparable to those of the sialomes of other argasid and ixodid ticks. This transcriptome provides a valuable reference database for ongoing proteomics studies of the salivary glands and saliva of O. moubata aimed at confirming and expanding previous data on the O. moubata sialoproteome.

While near-infrared spectroscopy (NIRS) haemodynamic measures have proven to be vastly useful in investigating human brain development, the haemodynamic response function (HRF) in infants is not yet fully understood. NIRS measurements of the oxidation state of mitochondrial enzyme cytochrome-c-oxidase (oxCCO) have the potential to yield key information about cellular oxygen utilisation and therefore energy metabolism. We used a broadband NIRS system to measure changes in oxCCO, in addition to haemodynamic changes, during functional activation in a group of 33 typically developing infants aged between 4 and 6 months. The responses were recorded over the right temporal lobe while the infants were presented with engaging videos containing social content. A significant increase in oxCCO was found in response to the social stimuli, with maximum increase of 0.238 ± 0.13 μM. These results are the first reported significant change in oxCCO in response to stimulus-evoked activation in human infants and open new vistas for investigating human infant brain function and its energy metabolism.

Functional magnetic resonance imaging (fMRI) is an indirect measure of neural activity which is modeled as a convolution of the latent neuronal response and the hemodynamic response function (HRF). Since the sources of HRF variability can be nonneural in nature, the measured fMRI signal does not faithfully represent underlying neural activity. Therefore, it is advantageous to deconvolve the HRF from the fMRI signal. However, since both latent neural activity and the voxel-specific HRF is unknown, the deconvolution must be blind. Existing blind deconvolution approaches employ highly parameterized models, and it is unclear whether these models have an over fitting problem. In order to address these issues, we 1) present a nonparametric deconvolution method based on homomorphic filtering to obtain the latent neuronal response from the fMRI signal and, 2) compare our approach to the best performing existing parametric model based on the estimation of the biophysical hemodynamic model using the Cubature Kalman Filter/Smoother. We hypothesized that if the results from nonparametric deconvolution closely resembled that obtained from parametric deconvolution, then the problem of over fitting during estimation in highly parameterized deconvolution models of fMRI could possibly be over stated. Both simulations and experimental results demonstrate support for our hypothesis since the estimated latent neural response from both parametric and nonparametric methods were highly correlated in the visual cortex. Further, simulations showed that both methods were effective in recovering the simulated ground truth of the latent neural response.

To determine the genetic and molecular basis for rheumatoid factor (RF) autoantibody reactivity in patients with destructive, erosive arthritis, we established a human lymphoblastoid cell line (hRF-1) from a patient with polyarthritis that produced an IgG RF mAb, mAb hRF-1. Studies of isolated H and L chains showed that the specificity of RF reactivity is conferred by mAb hRF-1 L chains. The L chain gene was cloned from a cDNA library prepared from hRF-1 cells. The nucleotide sequence was similar to known V kappa II L chains except for a two nucleotide change corresponding to a change of two amino acids in an invariable region of FR3. A germ-line gene with one of the nucleotide changes was identified by polymerase chain reaction in multiple cell lines, including K562 that does not rearrange Ig genes, but the other nucleotide change appeared to be due to mutation. Either or both of these amino acid changes may contribute to the RF reactivity, because an antibody with the same V kappa II L chain except for these two amino acid changes in FR3 did not have RF reactivity. The RF reactivity of isolated L chains from mAb hRF-1 was confirmed by transfecting COS cells with an expression vector encoding the hRF-1 kappa-chain and showing that the secreted k-chains had RF reactivity. Expression of this variant V kappa II L chain gene may form the basis for RF autoantibody reactivity in some patients.

Disruption of the early stages of information processing in limbic brain circuits may underlie symptoms of severe neuropsychiatric disorders. Prepulse inhibition of acoustic startle (PPI) is diminished in many of these disorders and may reflect the disruption of this CNS function. PPI is associated with brain activity in many of the same regions in humans as it is in laboratory animals, suggesting that neuroimaging studies in humans may help localize deficits that can then be elucidated in animal models. In this article, we employed a rapid presentation event-related design during continuous EPI BOLD scanning to examine hemodynamic response functions (HRFs) associated with PPI. Fourteen healthy participants listened to 100 pulse alone and 100 prepulse combined with pulse (prepulse-pulse) trials. PPI is the normalized difference in the startle response to the two trial types. Following the prepulse-pulse trials, the amplitudes of the HRFs in auditory cortices and in the anterior insula were increased, while in the cerebellum, thalamus and anterior cingulate, they were decreased, relative to the pulse alone trials. In addition, the timing of the prepulse-pulse responses was delayed in the auditory cortices, anterior insula and cerebellum. Finally, PPI measured outside the scanner was predicted by the difference in BOLD responses between trial types in the anterior insula and in the cerebellum. The results suggest that prepulse inhibition, and by extension early stages of information processing, modulate both the amplitude as well as timing of neural activity.

Many fMRI analysis methods use a model for the hemodynamic response function (HRF). Common models of the HRF, such as the Gaussian or Gamma functions, have parameters that are usually selected a priori by the data analyst. A new method is presented that characterizes the HRF over a wide range of parameters via three basis signals derived using principal component analysis (PCA). Covering the HRF variability, these three basis signals together with the stimulation pattern define signal subspaces which are applicable to both linear and nonlinear modeling and identification of the HRF and for various activation detection strategies. Analysis of simulated fMRI data using the proposed signal subspace showed increased detection sensitivity compared to the case of using a previously proposed trigonometric subspace. The methodology was also applied to activation detection in both event-related and block design experimental fMRI data using both linear and nonlinear modeling of the HRF. The activated regions were consistent with previous studies, indicating the ability of the proposed approach in detecting brain activation without a priori assumptions about the shape parameters of the HRF. The utility of the proposed basis functions in identifying the HRF is demonstrated by estimating the HRF in different activated regions.

A vast repertoire of methods is currently available to study effective brain connectivity based on neuroimaging data, among which lag-based measures can be distinguished. Although several studies have previously assessed the performance of such measures, their validity in different conditions remains unclear. In the current study, several lag-based effective connectivity measures are tested and benchmarked using simulated fMRI data, conceived to reflect a broad range of different situations with practical interest. The main goal is two-fold: 1) to provide a thorough overview of lag-based effective connectivity measures, and 2) to assess their performance in specific experimental conditions, thereby providing guidance for future effective connectivity studies involving fMRI. We focus on well-known lag-based measures, cover existing improvements and alternative formulations in some cases: Granger causality (GC), Geweke's Granger causality (GGC), directed transfer function (DTF), partial directed coherence (PDC), phase slope index (PSI), and transfer entropy (TE). Benchmarking consists in identifying causal relations in local field potential (LFP) networks that have their output convolved with a canonical hemodynamic response function (HRF) with varying node number, topology, coupling strength, neuronal delay, repetition time (TR), signal-to-noise ratio (SNR) and HRF variability. In a first set of simulations, we cover all possible combinations of discretized values of the previous variables, for networks with 2 and 3 nodes, and find that the measure with best performance (time-domain Granger Causality) is able to detect neuronal delays of a few hundreds of milliseconds with TRs between 0.25 and 2s and neuronal delays below 100ms for TRs that are also below 100ms, with more than 80% accuracy in realistic conditions. For networks with more than 3 nodes, we find that the number of nodes and the density of causal links degrade sensitivity, especially if the number of observations does not compensate for the increase in nodes, and that clustered networks can be more easily identified. In conclusion, this study argues in favor of the applicability of lag-based measures in the context of fMRI, provided that a stringent set of experimental specifications is met and that the chosen measure is applied with full knowledge of its limitations and specific constraints.

OBJECTIVE

We reported recently that early use of inhaled nitric oxide therapy (iNO) for term and late preterm infants with hypoxic respiratory failure (HRF) at an oxygenation index (OI) of ≥15 and <20 is associated with earlier discharge from the hospital, relative to babies treated at OI ≥25. The objective of the present analysis is to determine whether earlier use of iNO in this cohort leads to lower cost of medical care.

METHODS

We used a decision-analytic model, which was developed to compare hospital resource use and costs associated with early versus standard use of iNO in HRF. The model population included infants with moderate HRF caused by primary pulmonary hypertension with an OI ≥15 and <20. A hypothetical case population of 1000 patients was assumed and probabilistic sensitivity analyses were completed where all the clinical inputs into the model were varied. Two deterministic sensitivity analyses were also completed, one surrounding the hospital cost inputs and another surrounding the cost of iNO.

RESULTS

Early iNO was associated with fewer hospital days, fewer days of ventilation and fewer hours on extracorporeal membrane oxygenation (ECMO). In probabilistic sensitivity analyses, total costs per patient were $88,518 ± $7574 and $92,581 ± $9664 for early iNO and standard iNO, respectively. The probability of early iNO being cost-effective was approximately 72%, based on a willingness to pay $100,000 or less to prevent ECMO therapy and/or death. In both deterministic sensitivity analyses, early iNO was cost-saving.

CONCLUSIONS

Our analysis shows that early use of iNO at an OI of ≥15 and <20 may be associated with shorter hospitalizations and a decreased cost of care for term/late preterm infants with HRF associated with pulmonary hypertension. Our results are based on clinical data from a single trial; future research using data from real-world practice is warranted.

A convenient way to analyze blood-oxygen-level-dependent functional magnetic resonance imaging data consists of modeling the whole brain as a stationary, linear system characterized by its transfer function: the hemodynamic response function (HRF). HRF estimation, though of the greatest interest, is still under investigation, for the problem is ill-conditioned. In this paper, we recall the most general Bayesian model for HRF estimation and show how it can beneficially be translated in terms of Bayesian graphical models, leading to 1) a clear and efficient representation of all structural and functional relationships entailed by the model, and 2) a straightforward numerical scheme to approximate the joint posterior distribution, allowing for estimation of the HRF, as well as all other model parameters. We finally apply this novel technique on both simulations and real data.

OBJECTIVE

To determine whether complement regulatory proteins are present on human spermatozoa and whether antibodies to these proteins adversely affect sperm motility.

METHODS

Human sperm membrane proteins were solubilized and subjected to polyacrylamide gel electrophoresis followed by Western blot analysis against antibodies to complement component 1 inhibitor (C1-INH), decay-activating factor (DAF; CD55), membrane cofactor protein (MCP; CD46), and homologous restriction factor (HRF; CD59). Spermatozoa, obtained by a swim-up technique, were incubated in medium (control 1) and medium supplemented with antibodies to human albumin (control 2) and antibodies to these complement regulatory proteins. We used a computerized sperm motion analysis to determine the effect of these antibodies on sperm motion characteristics.

RESULTS

Complement regulatory proteins such as C1-INH, CD55, CD46, and CD59 were found in the sperm extracts as shown by Western blot analysis. The heat-treated (56 degrees C, 30 min) IgG fraction of antibodies to these proteins significantly reduced sperm motility in general and other motion parameters. Addition of complement did not affect these results except in the antibodies to CD46 in which the reducing action was further amplified.

CONCLUSIONS

Our data suggest that C1-INH, CD55, CD46, and CD59 are present on the sperm surface. These proteins may have biological functions, such as affecting sperm motility, besides the complement regulatory functions. In infertile men and women with antibodies that recognize one or more of these complement regulatory proteins, there may be problems related to poor sperm motility and survival in the reproductive tracts.

The temporal resolving power of blood oxygenation level-dependent (BOLD) functional magnetic resonance imaging (fMRI) at 3T was investigated in the visual and auditory cortices of the human brain. By using controlled temporal delays and selective visual hemifield stimulation, regions with similar (left vs. right occipital cortex) and different (occipital cortex vs. auditory cortex) vascular architectures were compared. Estimates of the time-to-peak (TTP) of the BOLD hemodynamic response function (hrf) were obtained using a spin echo (SE) sequence and compared to those acquired using a traditional gradient echo (GE) sequence. The hrf TTP in the visual cortex was found to be 4.73 s and 4.21 s for GE and SE, respectively. The auditory cortex response was significantly delayed, with TTPs of 4.95 s and 4.51 s for GE and SE, respectively. The GE response was able to resolve visual stimuli separated by 250 ms, whereas SE could resolve stimuli 500 ms apart. Apparent-diffusion-coefficient (ADC) compartmentalization of the BOLD signal was applied to restrict the vascular sensitivity of the SE and GE sequences. Limiting the response to voxels with ADCs < 0.8 x 10(-3) mm(2)/s improved the temporal resolving power of GE and SE BOLD to 125 ms and 250 ms, respectively.

Certain species of histamine-releasing factor (HRF) have been demonstrated to distinguish a select group of allergic patients from healthy subjects. An IgE-dependent mechanism of action has been suggested. The donor and IgE dependency of HRF produced by peripheral blood mononuclear cells (PBMCs) has not been clearly demonstrated. In this study, we have compared the response of basophils from normal subjects versus allergic patients with and without asthma. In addition, we have addressed the IgE dependency of HRF recovered from cultures of PBMCs, T cells, B cells, macrophages, and bronchoalveolar lavage fluid. We have demonstrated that basophils from allergic as well as normal subjects respond to PBMC-HRF. The response of basophils from allergic patients with asthma is significantly increased. This heightened response to HRF does not correlate with the severity of disease as assessed by baseline spirometry, medication, and skin test scores. Stripping of the membrane-bound IgE by incubating basophils with lactic acid causes a significant loss of sensitivity to HRF generated by PBMCs, T cells, B cells, and macrophages, as well as to HRF recovered from bronchoalveolar fluid. The loss of response can be restored by sera from patients with asthma but not from normal subjects or by myeloma IgE. In addition, poorly responsive basophils from normal subjects can be rendered sensitive by incubating with sera from patients with asthma. The capacity of a given serum from a patient with asthma to restore the response to HRF is not correlated with the total concentration of IgE in the serum.(ABSTRACT TRUNCATED AT 250 WORDS)

OBJECTIVE

To analyze the spatial distribution of hemorrhagic fever with renal syndrome (HFRS) in China by geographic information system, and to draw up a map on HRFS risk areas.

METHODS

A set of database was set up using the information collected and linked to electronic maps of China in a software ArcGIS 8.01 from 41 HFRS surveillance sites during 1995 - 1998. A HFRS spatial distribution model was developed using inverse distance weighted interpolation of ArcGIS's spatial analysis method. The normalized difference vegetation index (NDVI) in each HFRS surveillance site was extracted from SPOT4 satellite vegetation imagery. Correlation analysis was performed through SPSS 10.0 to analyze the association between NDVI and HFRS incidence, HFRS risk areas were mapped under different colors.

RESULTS

Spatial distribution model from HFRS surveillance sites showed that HFRS foci mainly presented in the Heilongjiang River drainage, the middle and lower reaches of the Yellow River, the middle and lower reaches of the Yangtze River, and the Jinghang grant Canal-Huaihe River drainage. It was consistent with HFRS distribution map derived from national infectious disease reporting system. Correlation analysis indicated that HFRS incidence rates were significantly associated with NDVI (r = 0.417, P < 0.01). The HFRS risk areas was mapped according to NDVI of each surveillance site.

CONCLUSIONS

It is promising to apply GIS technology in predication of the distribution of HFRS by establishing this prediction model.

BACKGROUND

Asthma is a disease that affects all ages, races and ethnic groups. Its incidence is increasing both in Westernized countries and underdeveloped countries. It involves inflammation, genetics and environment and therefore, proteins that exacerbate the asthmatic, allergic phenotype are important. Our laboratory purified and cloned a histamine releasing factor (HRF) that was a complete stimulus for histamine and IL-4 secretion from a subpopulation of allergic donors' basophils. Throughout the course of studying HRF, it was uncovered that HRF enhances or primes histamine release and IL-13 production from all anti-IgE antibody stimulated basophils. In order to further delineate the biology of HRF, we generated a mouse model.

RESULTS

We constructed an inducible transgenic mouse model with HRF targeted to lung epithelial cells, via the Clara cells. In antigen naïve mice, overproduction of HRF yielded increases in BAL macrophages and statistical increases in mRNA levels for MCP-1 in the HRF transgenic mice compared to littermate controls. In addition to demonstrating intracellular HRF in the lung epithelial cells, we have also been able to document HRF's presence extracellularly in the BAL fluid of these transgenic mice. Furthermore, in the OVA challenged model, we show that HRF exacerbates the allergic, asthmatic responses. We found statistically significant increases in serum and BAL IgE, IL-4 protein and eosinophils in transgenic mice compared to controls.

CONCLUSIONS

This mouse model demonstrates that HRF expression enhances allergic, asthmatic inflammation and can now be used as a tool to further dissect the biology of HRF.

Histamine-releasing factors (HRF) that release mediators from human basophils by interacting with IgE have been identified from different cell sources, including lymphocytes, monocytes, thrombocytes and endothelial cells. These factors are studied in view of their potential importance as a stimulus in chronic inflammation. In this report we investigated the qualitative variability of the histamine-releasing activity in the supernatants of activated mononuclear cells. Purified human mononuclear cells of 8 donors were activated with streptokinase/streptodornase (SK/SD) and the supernatants (HRF-MN) were tested for histamine-releasing activity (HRA) in both allergic (RAST positive for inhalant allergens) and nonallergic individuals. Four of the eight HRF-MN supernatants were discriminating, i.e. showing no histamine-release response with nonallergic individuals, whereas four supernatants were not. Two of the HRF-MN supernatants that exhibited discriminating properties were studied in more detail. The response to HRF-MN was tested (1) in a direct bioassay on basophils of allergic (RAST positive for inhalant allergens) and nonallergic individuals and (2) in an indirect bioassay with 70% pure basophils of RAST-negative donors after passive sensitization with sera of allergic donors. An association was found between the response to HRF-MN and the RAST for inhalant allergens: none (0/12) of the RAST-negative but 15/22 of the RAST-positive individuals were HRF-MN responders. The IgE dependency of HRF-MN was shown e.g. by inhibition of passive sensitization by preincubating a responder serum with monoclonal antibody (moAb) anti-IgE MH25-1. Our results are in contrast with findings of other investigators who use pooled supernatants and demonstrated HRF-MN responsiveness with both allergic and nonallergic donors.(ABSTRACT TRUNCATED AT 250 WORDS)

The duration and severity of the allergic response are variable. Even though antigens are rapidly cleared from the individual, an acute allergic response is frequently followed by a recrudescence of symptoms hours or even days after the initial exposure. Experimentally, the cellular infiltrates and mediators released during this late response resemble those associated with chronic inflammatory disease. Although basophils are present in this late reaction, the stimuli for their activation remain unknown. A heterogeneous group of unique cytokines called histamine-releasing factors (HRF), discovered over a decade ago, may well play a role in stimulating basophils during this late-phase reaction. These factors have been reported from a variety of cell sources including alveolar macrophages, platelets, vascular endothelial cells, B and T lymphocytes, mononuclear cell cultures, the U937 monocyte/macrophage-like cell line and the RPMI 8866 B cell line. These ubiquitous factors cause non-cytotoxic, calcium-dependent mediator release from human basophils in vitro and are also present and active in vivo. Purification attempts have revealed that HRF exists in at least three forms, based on molecular weight. In our hands, the mechanism of mediator release by one of the forms of HRF is IgE dependent. Since only about 50% of allergic donors' basophils respond to HRF, a heretofore unappreciated heterogeneity of IgE was revealed. The presence of HRF has been shown to correlate with severity of allergic disease in children with food allergies, with symptoms in the late-phase response in adults and with severity of the allergic response to an inhaled antigen. Thus, the study of HRF has evolved over the last decade and may lead to better understanding of the complex allergic response.

BACKGROUND

Histamine-releasing factor was recently shown to be clinically relevant in allergic rhinitis and asthma. HRF could also be involved in the pathogenicity of chronic idiopathic urticaria (CU). The purpose of this study was to investigate the role of HRF in the pathophysiology of CU.

METHODS

Blisters were induced on lesional and nonlesional skin of 12 patients with CU and on normal skin of five control subjects. HRF activity and histamine content were measured in all samples recovered from each skin site.

RESULTS

Significantly more HRF was found in blister fluids from lesional skin of patients with CU as compared with nonlesional skin and skin of control subjects. In addition, histamine content in blister fluids from affected skin of patients with CU was significantly higher in comparison with both nonlesional skin of patients with CU and skin of control subjects. HRF activity was also higher in blister fluids from nonlesional skin of patients with CU than that of control subjects, in spite of equivalent histamine content.

CONCLUSIONS

These data suggest that the inflammatory reaction found in CU disease is associated with the cutaneous release of HRF.

The aim of the study was to evaluate whether the Heidelberg retina flowmeter (HRF), a new device for retinal and anterior optic nerve blood flow assessment, can gauge, at least semiquantitatively, a known effect such as an increase in optic nerve blood flow by hypercapnia or a decrease in optic nerve blood flow by hyperoxia or high intraocular pressure (IOP). Measurements with the HRF were obtained at the papilla of three groups of 5 young healthy subjects (1) at baseline and after breathing 5% carbogen, (2) at baseline and after breathing 100% oxygen and (3) at baseline and after increasing IOP to 20 and 50 mm Hg. The changes in the value of the HRF parameter 'flow' were analyzed by means of a paired Student's t test. Breathing 100% oxygen for 7 min resulted in a statistically significant decrease of 34.7+/-2.5% (mean+/-SEM) in HR parameter 'flow' (p < 0.01) at the papilla. Breathing 5% carbogen for 7 min resulted in a statistically significant increase of 18.3+/-2.6% in HRF parameter 'flow' (p = 0.024). Increasing IOP to 20 mm Hg did not result in a statistically significant change in HRF parameter 'flow' (-9.6+/-7.4%; p = 0.13). Increasing IOP from 20 to 50 mm Hg, however, resulted in a statistically significant decrease of 40.1+/-6.6% in HRF parameter 'flow' (p = 0.003). With the applied stimuli, the HRF parameter 'flow' changed in the expected direction, i.e. an increase with hypercapnia and a decrease with hyperoxia or high IOP. The simplicity of use of the HRF instrument suggests that it might be well suited for a non-invasive, at least semiquantitative, assessment of changes in blood flow at the papilla.