Outcomes of subsequent abdominal operations after an initial ventral hernia repair

INTRODUCTION

Nearly 20% of ventral hernia repair (VHR) patients require a subsequent abdominal operation (SAO), and mesh position may impact the complexity and outcome of the SAO.

METHODS

Retrospective review of VHR with mesh from 2006 to 2020 from an internal database and the ACHQC. Primary outcomes measured incidence, complexity, and complications of SAO relative to mesh position.

RESULTS

SAO was required in 433 of 2539 (17.1%) patients, totaling 671 operations; 197/893 (22.1%) with intraperitoneal mesh (IPM) and 236/1646 (14.3%) with extraperitoneal mesh (EPM; p ​< ​0.001). SAO was directly related to VHR in 180 (232 total SAOs) and unrelated in 253 (439 total SAOs). There were no significant differences in complications after SAO between IPM and EPM, nor any difference in adhesion complexity.

CONCLUSION

Incidence of SAO is higher with IPM, but surgical outcomes are similar. Due to the risk of secondary mesh infection with IPM, significantly more of these were removed at the time of SAO.

The use of WHAM-FTOX, parameterized with laboratory data, to simulate zooplankton species richness in acid- and metal- contaminated lakes

The WHAM-F_TOX model quantifies cation toxicity towards freshwater organisms, assuming an additive toxic response to the amounts of protons and metals accumulated by an organism. We combined a parameterization of the model, using data from multi-species laboratory toxicity tests, with a fitted field species sensitivity distribution, to simulate the species richness (n_sp) of crustacean zooplankton in acid- and metal-contaminated lakes near Sudbury, Ontario over several decades, and also in reference (uncontaminated) lakes. A good description of variation in toxic response among the zooplankton species was achieved with a log-normal distribution of a new parameter, β, which characterizes an organism's intrinsic sensitivity towards toxic cations; the greater is β, the more sensitive is the species. The use of β assumes that while species vary in their sensitivity, the relative toxicities of different metals are the same for each species (common relative sensitivity). Unbiased agreements between simulated and observed n_sp were obtained with a high correlation (r² = 0.81, p < 0.0001, n = 217). Variations in zooplankton species richness in the Sudbury lakes are calculated to be dominated by toxic responses to H, Al, Cu and Ni, with a small contribution from Zn, and negligible effects of Cd, Hg and Pb. According to the model, some of the Sudbury lakes were affected predominantly by acidification (H and Al), while others were most influenced by toxic heavy metals (Ni, Cu, Zn); for lakes in the latter category, the relative importance of heavy metals, compared to H and Al, has increased over time. The results suggest that, if common relative sensitivity operates, n_sp can be modelled on the basis of a single set of parameters characterizing the average toxic effects of different cations, together with a species sensitivity distribution.

Fatal Agricultural Accidents in Kansas: A Thirty-Nine-Year Follow-Up Study with an Emphasis on Vehicular Fatalities

The purpose of this study was to evaluate trends in agricultural mortality before and after implementation of safety initiatives. Retrospective review of Kansas mortality data from agriculture-related injuries from 1979 to 2018. The 39-year period was stratified into four periods to compare mechanisms of injury and fatality rates between study periods. There were 780 agricultural-related deaths. Mean age significantly increased between study Period I to Period IV from 46.4 to 55.3 years (P = 0.013). Tractors remain the primary cause of farm-vehicle mortality overall; however, tractor-related deaths significantly decreased during the study periods from 75.6% to 44.3% (P < 0.001). Tractor rollover mortality also decreased from 50.8% to 25.6% (P = 0.036). ATV-related deaths significantly increased from study Period II to III (5.1% to 23.9%, P < 0.001), but decreased from Period III to IV (23.9% to 17.0%). Tractor-related fatalities are decreasing, but tractors still remain the most dangerous piece of farm equipment. ATV-related fatalities are a continued concern. Continued rural education and emphasis on the use of rollover protection structures is a critical focus in the effort to prevent fatal farming injuries.

Impact of Sampling and Storage Techniques on Beef Muscle Measurements During Aging

ObjectivesThis objective was to determine if variations in beef sampling techniques utilized by meat researchers have a significant impact on beef muscle measurements during aging.Materials and MethodsTen beef short loins (IMPS 180) were purchased from a commercial packing plant within 48 h of slaughter. Loins were transported to the NDSU Meat Science laboratory where they were mapped into four sections from most anterior (1) to most posterior (4). Within sections, two, 40-g samples were removed; one sample was vacuum packaged (SMALL-VAC) and the other sample was stored in a wire-closure sealed bag (SMALL-BAG). The remaining whole short loin was vacuum packaged. All samples and whole short loins were stored at 4°C for 10 d. At 10 d, the short loins were sampled again where one, 40-g sample was removed from each mapped section (WHOLE-VAC). Purge loss was measured by weighing each sample prior to packaging treatment and at the end of the 10-d aging period; percentage change in weight was calculated. Troponin-T degradation was determined by western blot. Briefly, protein was extracted in an SDS-phosphate buffer, separated by SDS-PAGE under reducing conditions, and transferred to PVDF membranes. Western analysis was done using an anti-troponin-T antibody (clone JLT 12), and immunoreactive bands (Band 1 = doublet ∼42 to 45 kDa; Band 2 = doublet ∼ 36 to 38 kDa, Band 3 = 30 kDa) were analyzed for differences in density. Sarcomere length was determined using HeNe laser diffraction. Thinly sliced samples (∼50 to 100 mg) were placed in a sucrose-phosphate buffer and subjected to beadmill homogenization. A drop of the homogenate was placed on a glass slide, diffraction patterns were measured, and sarcomere length was calculated. Thiobarbituric acid reactive substances (TBARS) were assessed using a colorimetric assay. Analysis was conducted using Proc Mixed procedure of SAS where storage type, section location, and their interaction were used as fixed effects.ResultsThere was a storage type by section interaction (P = 0.017) that occurred with purge loss. SMALL-VAC samples released more purge than SMALL-BAG from the more posterior samples. Troponin-T Band 1 tended to be less (P = 0.07) in WHOLE-VAC samples compared with SMALL-VAC and SMALL-BAG. There was a storage type by section interaction (P = 0.02) where the most posterior SMALL-BAG samples had greater Band 2. There were no differences (P ≥ 0.25) in Band 3 between treatments. There was no difference (P = 0.29) in sarcomere length due storage type. However, there was a difference (P = 0.01) in sarcomere length between sections, where the shortest sarcomeres were in the center of the strip loin and longest sarcomeres on either end. There was a storage type by section interaction (P = 0.02) for TBARS where concentration was greatest in the most posterior portion of SMALL-BAG compared with WHOLE-VAC.ConclusionCollection of smaller samples for aging studies may not be representative of samples aged in a whole primal cut and may influence research outcomes.

Effect of Feeding a Low Vitamin a Diet to Beef Steers on Calpain 1 Activation during Meat Aging

ObjectivesThe objective of the study was to determine if a vitamin A deficient diet during beef finishing influences calpain 1 activation during meat aging.Materials and MethodsSixty-four steers of approximately 7 mo of age were subjected to a 14-d acclimation period followed by a 95-d growing period on a low vitamin A diet (1017 IU vitamin A/kg DM) designed to deplete liver vitamin A stores. Steers were assigned to a randomized complete blocked design with a 2 × 2 arrangement of treatments (breed: commercial Angus, n = 32, and purebred Simmental, n = 32; and a Low Vitamin A diet or a control diet). The low Vitamin A (LVA) treatment was a finishing diet with no supplemental vitamin A (723 IU vitamin A/kg DM). The control (CON) treatment was the LVA diet plus supplementation with 2200 IU vitamin A/kg DM for a total of 2923 IU vitamin A/kg DM. Serum retinol concentrations were monitored at the beginning and end of treatment. Upon completion of finishing, steers were slaughtered in two groups at a commercial plant. After fabrication, boneless strip loins (IMPS 180) were collected and transported to NDSU. Samples (approximately 40 g) were collected from the anterior portion of the strip loin on d-2 and d-7 of aging and immediately frozen. Protein was extracted from meat samples in fractionation buffers to yield sarcoplasmic and myofibrillar portions, separated by SDS-PAGE, and transferred to PVDF membranes. Immunoblot analysis was done using anti-desmin (d-2 and d-7) and anti-calpain 1 (d-2) antibodies, and results were visualized and documented. A pooled control was run on all membranes and set to a value of one for normalizing results. All experimental data were analyzed using the Proc Mixed procedure of SAS with breed of steers, dietary treatments, their interaction and slaughter date used as a fixed effect.ResultsCalpain 1 autolysis in the sarcoplasmic protein fraction of the d-2 aged loin samples were not affected by treatment or breed. The myofibrillar protein fraction from Angus loins had greater (P = 0.02) accumulation of the 76 kDa calpain 1 autolysis product than that from the Simmental loins; the myofibrillar fraction of the loins from the LVA treatment tended (P = 0.07) to have more 76 kDa calpain 1 autolysis product than that from the CON. There were not any differences (P > 0.19) in the 80 kDa calpain 1 band or the 78 kDa calpain 1 intermediate autolysis product in the myofibrillar fraction. There was a treatment by breed interaction (P = 0.01) for desmin in the d-7 aged loins where Angus loins from the CON treatment had less accumulation of the 46 kDa band than Angus loins on the LVA treatment and Simmental loins from either treatment.ConclusionVitamin A restriction increased protein proteolysis in Angus but not in Simmental steers. The increased calpain 1 autolysis in Angus vs. Simmental, regardless of Vitamin A treatment, indicates a genetic difference that may be the driver for the increased protein degradation in steers a restricted vitamin A diet.

Tenderness and Juiciness of Beef Steaks from Varying Hot Carcass Weights

ObjectivesOur objectives were to determine how hot carcass weights affected temperature decline and pH decline of carcasses, and subsequently shear force, juiciness and color of steaks.Materials and MethodsCarcasses (n = 59) were selected at a commercial abattoir over five collection days at approximately 45 min after exsanguination and sorted by hot carcass weight. Carcasses were separated into light (< 363 kg), medium (363 to 408 kg), or heavy (> 408 kg) weight groups. Temperature decline was monitored with a data logger for 24 h with one probe inserted into the longissimus muscle at approximately the sixth rib and one probe inserted directly into the center of the semimembranosus muscle. Muscle pH was measured in the longissimus and semimembranosus muscle at 0, 4, and 24 h after carcasses were moved into chill coolers. After approximately 24 h of chilling, ribeye area, 12th rib fat, KPH, and USDA Quality and Yield Grades were collected. Ribeye rolls (IMPS 112A) and inside rounds (IMPS 160A) were transported to the North Dakota State University Meat Laboratory and aged in vacuum packaging for 14 d. Ribeye and rounds steaks were fabricated for Warner-Bratzler shear force and color analysis. Color analysis was determined on each steak using a Minolta colorimeter after a 30-min bloom time. A 50-g sample was collected for drip loss analysis. Data were analyzed using the mixed procedure of SAS.ResultsLongissimus muscle temperature at 4 h was less (P = 0.02) in light carcasses compared with heavy weight carcasses and semimembranosus muscle temperature was less (P < 0.0001) in light and medium weight carcasses compared with heavy weight carcasses. There were no differences in pH decline (P ≥ 0.16) among hot carcass weight groups. There were no differences in fat thickness, KPH or marbling score (P ≥ 0.12) among hot carcass weight groups. Longissimus area (P = 0.0002) was larger and USDA final yield grade was greater (P = 0.04) among hot carcass weight groups. There were no differences in drip loss, cook loss or WBSF in either longissimus or semimembranosus muscles (P ≥ 0.10) among carcass groups. Color data indicated that ribeye and round steaks from heavy weight carcasses were redder than steaks from light weight carcasses (P ≤ 0.02).ConclusionHot carcass weight did not have an influence on objective measures of meat palatability traits; however, carcass weight did have an effect on color.

Fusion proteins consisting of Bet v 1 and Phl p 5 form IgE-reactive aggregates with reduced allergenic activity

The cross-linking of effector cell-bound IgE antibodies by allergens induces the release of inflammatory mediators which are responsible for the symptoms of allergy. We demonstrate that a recombinant hybrid molecule consisting of the major birch (Bet v 1) and grass (Phl p 5) pollen allergen exhibited reduced allergenic activity as compared to equimolar mixes of the isolated allergens in basophil activation experiments. The reduced allergenic activity of the hybrid was not due to reduced IgE reactivity as demonstrated by IgE binding experiments using sera from allergic patients. Physicochemical characterization of the hybrid by size exclusion chromatography, dynamic light scattering, negative-stain electron microscopy and circular dichroism showed that the hybrid occurred as folded aggregate whereas the isolated allergens were folded monomeric proteins. IgG antibodies raised in rabbits against epitopes of Bet v 1 and Phl p 5 showed reduced reactivity with the hybrid compared to the monomeric allergens. Our results thus demonstrate that aggregation can induce changes in the conformation of allergens and lead to the reduction of allergenic activity. This is a new mechanism for reducing the allergenic activity of allergens which may be important for modifying allergens to exhibit reduced side effects when used for allergen-specific immunotherapy.

Similar localization of conformational IgE epitopes on the house dust mite allergens Der p 5 and Der p 21 despite limited IgE cross-reactivity

BACKGROUND

Due to high IgE recognition frequency and high allergenic activity, Der p 5 and Der p 21 are clinically important house dust mite (HDM) allergens. The objective of this study was to characterize the immunodominant IgE epitopes of Der p 5 and Der p 21 responsible for their high allergenic activity.

METHODS

A panel of 12 overlapping peptides spanning the Der p 5 and Der p 21 sequence were synthesized to search for sequential IgE epitopes by direct testing for allergic patients' IgE reactivity. Peptide-specific antibodies raised in rabbits were used in inhibition studies for localizing conformational IgE epitopes which were visualized on the surfaces of the allergen structures by molecular modelling. IgE cross-reactivity between the allergens was investigated by IgE inhibition studies.

RESULTS

Immunodominant IgE epitopes defined by allergic patients' IgE on Der p 5 and Der p 21 were primarily of the conformational, discontinuous type including N- and C-terminal portions of the protein. They could be located on each allergen on one area with similar localization, but despite similar structure of the allergens, no relevant IgE cross-reactivity could be detected.

CONCLUSION

Our study shows that Der p 5 and Der p 21 contain a major conformational IgE epitope-containing area located on similar portions of their structure, but they lack relevant IgE cross-reactivity. These data are important for the development of modern allergy vaccines based on defined molecules for allergen-specific immunotherapy of HDM allergy.

Isolation of a high-affinity Bet v 1-specific IgG-derived ScFv from a subject vaccinated with hypoallergenic Bet v 1 fragments

Background

Recombinant hypoallergenic allergen derivatives have been used in clinical immunotherapy studies, and clinical efficacy seems to be related to the induction of blocking IgG antibodies recognizing the wild‐type allergens. However, so far no treatment‐induced IgG antibodies have been characterized.

Objective

To clone, express, and characterize IgG antibodies induced by vaccination with two hypoallergenic recombinant fragments of the major birch pollen allergen, Bet v 1 in a nonallergic subject.

Methods

A phage‐displayed combinatorial single‐chain fragment (ScFv) library was constructed from blood of the immunized subject and screened for Bet v 1‐reactive antibody fragments. ScFvs were tested for specificity and cross‐reactivity to native Bet v 1 and related pollen and food allergens, and epitope mapping was performed. Germline ancestor genes of the antibody were analyzed with the ImMunoGeneTics (IMGT) database. The affinity to Bet v 1 and cross‐reactive allergens was determined by surface plasmon resonance measurements. The ability to inhibit patients’ IgE binding to ELISA plate‐bound allergens and allergen‐induced basophil activation was assessed.

Results

A combinatorial ScFv library was obtained from the vaccinated donor after three injections with the Bet v 1 fragments. Despite being almost in germline configuration, ScFv (clone H3‐1) reacted with high affinity to native Bet v 1 and homologous allergens, inhibited allergic patients’ polyclonal IgE binding to Bet v 1, and partially suppressed allergen‐induced basophil activation.

Conclusion

Immunization with unfolded hypoallergenic allergen derivatives induces high‐affinity antibodies even in nonallergic subjects which recognize the folded wild‐type allergens and inhibit polyclonal IgE binding of allergic patients.

Epitope specificity determines cross-protection of a SIT-induced IgG4 antibody

Background

The calcium‐binding 2EF‐hand protein Phl p 7 from timothy grass pollen is a highly cross‐reactive pollen pan‐allergen that can induce severe clinical symptoms in allergic patients. Recently, a human monoclonal Phl p 7‐specific IgG₄ antibody (mAb102.1F10) was isolated from a patient who had received grass pollen‐specific immunotherapy (SIT).

Methods

We studied epitope specificity, cross‐reactivity, affinity and cross‐protection of mAb102.1F10 towards homologous calcium‐binding pollen allergens. Sequence comparisons and molecular modelling studies were performed with ClustalW and SPADE, respectively. Surface plasmon resonance measurements were made with purified recombinant allergens. Binding and cross‐reactivity of patients' IgE and mAb102.1F10 to calcium‐binding allergens and peptides thereof were studied with quantitative RAST‐based methods, in ELISA, basophil activation and IgE‐facilitated allergen presentation experiments.

Results

Allergens from timothy grass (Phl p 7), alder (Aln g 4), birch (Bet v 4), turnip rape (Bra r 1), lamb's quarter (Che a 3) and olive (Ole e 3, Ole e 8) showed high sequence similarity and cross‐reacted with allergic patients' IgE. mAb102.1F10 bound the C‐terminal portion of Phl p 7 in a calcium‐dependent manner. It cross‐reacted with high affinity with Ole e 3, whereas binding and affinity to the other allergens were low. mAb102.1F10 showed limited cross‐inhibition of patients' IgE binding and basophil activation. Sequence comparison and surface exposure calculations identified three amino acids likely to be responsible for limited cross‐reactivity.

Conclusions

Our results demonstrate that a small number of amino acid differences among cross‐reactive allergens can reduce the affinity of binding by a SIT‐induced IgG and thus limit cross‐protection.

High-resolution crystal structure and IgE recognition of the major grass pollen allergen Phl p 3

BACKGROUND

Group 2 and 3 grass pollen allergens are major allergens with high allergenic activity and exhibit structural similarity with the C-terminal portion of major group 1 allergens. In this study, we aimed to determine the crystal structure of timothy grass pollen allergen, Phl p 3, and to study its IgE recognition and cross-reactivity with group 2 and group 1 allergens.

METHODS

The three-dimensional structure of Phl p 3 was solved by X-ray crystallography and compared with the structures of group 1 and 2 grass pollen allergens. Cross-reactivity was studied using a human monoclonal antibody which inhibits allergic patients' IgE binding and by IgE inhibition experiments with patients' sera. Conformational Phl p 3 IgE epitopes were predicted with the algorithm SPADE, and Phl p 3 variants containing single point mutations in the predicted IgE binding sites were produced to analyze allergic patients' IgE binding.

RESULTS

Phl p 3 is a globular β-sandwich protein showing structural similarity to Phl p 2 and the Phl p 1-C-terminal domain. Phl p 3 showed IgE cross-reactivity with group 2 allergens but not with group 1 allergens. SPADE identified two conformational IgE epitope-containing areas, of which one overlaps with the epitope defined by the monoclonal antibody. The mutation of arginine 68 to alanine completely abolished binding of the blocking antibody. This mutation and a mutation of D13 in the predicted second IgE epitope area also reduced allergic patients' IgE binding.

CONCLUSION

Group 3 and group 2 grass pollen allergens are cross-reactive allergens containing conformational IgE epitopes. They lack relevant IgE cross-reactivity with group 1 allergens and therefore need to be included in diagnostic tests and allergen-specific treatments in addition to group 1 allergens.

Schwingungsspektren und Normalkoordinatenanalyse der Tetrahalogeno-closo-1,2-diphosphahexaborane P2B4X4, X = Cl, Br / Vibrational Spectra and Normal Coordinate Analysis of the Tetrahalogeno-closo-1,2-diphosphahexaboranes P2B4X4, X = Cl, Br

High resolution vibrational spectra of the tetrahalogeno-closo-1,2-diphosphahexaboranes P2B4X4, X = Cl, Br have been measured at low temperatures (20 - 60 K). The boron-halogen stretching vibrations are observed below 370 cm-1 while the P-P valence vibrations are found at 414 (Cl) and 372 cm-1 (Br). Due to the presence of the boron isotopes 10B and 11B the P-P stretching vibrations and the cage modes in the region of 550 to 1200 cm-1 are split. Based on the crystallographic data of P2B4C14 normal coordinate analyses have been performed. Using a set of 16 force constants (e.g. fd(PP) = 1.35 (X = Cl) and 1.20 (Br), fd(BB) = 1.30 / 1.65 (Cl) and 1.45 /1.60 (Br), fd(BX) = 4.40 (Cl) and 3.53 (Br) mdyn / Å) a good agreement of observed and calculated frequencies has been achieved.

Global warming triggers the loss of a key Arctic refugium

We document the rapid transformation of one of the Earth's last remaining Arctic refugia, a change that is being driven by global warming. In stark contrast to the amplified warming observed throughout much of the Arctic, the Hudson Bay Lowlands (HBL) of subarctic Canada has maintained cool temperatures, largely due to the counteracting effects of persistent sea ice. However, since the mid-1990s, climate of the HBL has passed a tipping point, the pace and magnitude of which is exceptional even by Arctic standards, exceeding the range of regional long-term variability. Using high-resolution, palaeolimnological records of algal remains in dated lake sediment cores, we report that, within this short period of intense warming, striking biological changes have occurred in the region's freshwater ecosystems. The delayed and intense warming in this remote region provides a natural observatory for testing ecosystem resilience under a rapidly changing climate, in the absence of direct anthropogenic influences. The environmental repercussions of this climate change are of global significance, influencing the huge store of carbon in the region's extensive peatlands, the world's southern-most polar bear population that depends upon Hudson Bay sea ice and permafrost for survival, and native communities who rely on this landscape for sustenance.

Carrier-bound nonallergenic Der p 2 peptides induce IgG antibodies blocking allergen-induced basophil activation in allergic patients

BACKGROUND

More than 90% of house dust mite-allergic patients are sensitized to the major Dermatophagoides pteronyssinus allergen, Der p 2. The aim of this study was to develop and characterize an allergy vaccine based on carrier-bound Der p 2 peptides, which should allow reducing IgE- and T-cell-mediated side-effects during specific immunotherapy (SIT).

METHODS

Five Der p 2 peptides (P1-P5) were synthesized and analyzed regarding IgE reactivity and allergenic activity. Lymphoproliferative and cytokine responses induced with Der p 2 and Der p 2 peptides were determined in peripheral blood mononuclear cells from mite-allergic patients. Der p 2-specific IgG antibodies induced with carrier-bound Der p 2 peptides in mice and rabbits were tested for their capacity to inhibit IgE binding and basophil activation in allergic patients.

RESULTS

Of five overlapping peptides (P1-P5) covering the Der p 2 sequence, two peptides (P2 and P4) were identified, which showed no relevant IgE reactivity, allergenic activity, and induced lower Der p 2-specific T-cell activation than Der p 2. However, when coupled to a carrier, P2 and P4 induced Der p 2-specific IgG antibodies in animals, which inhibited allergic patients' IgE binding to the allergen and allergen-induced basophil activation similar as antibodies induced with Der p 2.

CONCLUSIONS

Carrier-bound Der p 2 peptides should allow avoiding IgE-mediated side-effects, and because of their low potential to activate allergen-specific T cells, they may reduce late-phase side-effects during SIT. Further, these peptides may be also useful for prophylactic vaccination.

Characterization of Der p 21, a new important allergen derived from the gut of house dust mites

BACKGROUND

The house dust mite (HDM) Dermatophagoides pteronyssinus is a major allergen source eliciting allergic asthma. The aim of the study was to identify new important HDM allergens associated with allergic asthma.

METHODS

A cDNA coding for a new mite allergen, designated Der p 21, was isolated using immunoglobulin E (IgE) antibodies from patients with allergic asthma out of a D. pteronyssinus expression cDNA library and expressed in Escherichia coli.

RESULTS

Circular dichroism analysis of the purified allergen showed that rDer p 21 (14 726 Da) is one of the few mite allergens with an alpha-helical secondary structure. The protein exhibited high thermal stability and refolding capacity, and, as determined by small angle X-ray scattering, formed a dimer consisting of two flat triangles. rDer p 21 bound high levels of patients' IgE antibodies and showed high allergenic activity in basophil activation experiments. Rabbit anti-Der p 21 IgG antibodies inhibited mite-allergic patients' IgE binding and allowed the ultrastructural localization of the allergen in the midgut (epithelium, lumen and faeces) of D. pteronyssinus by immunogold electron microscopy. Der p 21 revealed sequence homology with group 5 mite allergens, but IgE and IgG reactivity data and cross-inhibition studies identified it as a new mite allergen.

CONCLUSIONS

Der p 21 is a new important mite allergen which is liberated into the environment via faecal particles and hence may be associated with allergic asthma.

Characterization of a Hypoallergenic Recombinant Bet v 1 Variant as a Candidate for Allergen-Specific Immunotherapy

BACKGROUND

Recombinant allergens and especially their hypoallergenic variants are promising candidates for a more effective and safer specific immunotherapy.

METHODS

Physicochemical and immunological characteristics of a folding variant of recombinant Bet v 1 (rBet v 1-FV) were investigated in comparison to natural Bet v 1 (nBet v 1) and the correctly folded recombinant Bet v 1 (rBet v 1-WT) by SDS-PAGE, size exclusion chromatography, multi-angle light scattering, circular dichroism, immunoblotting and enzyme allergosorbent test inhibition assay for detection of IgE reactivity and ELISA with Bet v 1-specific monoclonal antibodies. The functional IgE reactivity of the different Bet v 1 proteins was investigated using basophil activation in terms of CD203c expression and histamine release. T cell reactivity was investigated using T cell lines raised from birch pollen-allergic subjects against nBet v 1. Immunogenicity was investigated in mice.

RESULTS

Physicochemical characterization revealed purity, homogeneity and monomeric properties of rBet v 1-FV. Unlike nBet v 1 and rBet v 1-WT, rBet v 1-FV showed almost no IgE binding in immunoblots. The reduction of allergenicity was further proved by IgE-binding inhibition assays, basophil activation and histamine release. T cell reactivity was completely conserved, as demonstrated by proliferation of Bet v 1-specific T cell lines with multiple epitope specificities. rBet v 1-FV showed strong immunogenicity in mice.

CONCLUSIONS

Due to its reduced IgE reactivity and decreased capacity to activate basophils, but retained T cell reactivity and strong immunogenicity, rBet v 1-FV proved to be a very promising candidate for specific immunotherapy in birch pollen-allergic subjects.

Generation of a low immunoglobulin E-binding mutant of the timothy grass pollen major allergen Phl p 5a

BACKGROUND

Immunotherapy of grass pollen allergy is currently based on the administration of pollen extracts containing natural allergens. Specifically designed recombinant allergens with reduced IgE reactivity could be used in safer and more efficacious future therapy concepts.

OBJECTIVES

This study aimed to generate hypoallergenic variants of the timothy grass major allergen Phl p 5a as candidates for allergen-specific immunotherapy.

METHODS

Three deletion mutants were produced in Escherichia coli and subsequently purified. The overall IgE-binding capacity of the mutants was compared with the recombinant wild-type allergen by membrane blot and IgE-inhibition assays. The capacity for effector cell activation was determined in basophil activation assays. T cell proliferation assays with allergen-specific T cell lines were performed to confirm the retention of T cell reactivity. Structural properties were characterized by circular dichroism analysis and homogeneity by native isoelectric focusing. The deletion sites were mapped on homology models comprising the N- and C-terminal halves of Phl p 5a, respectively.

RESULTS

The double-deletion mutant rPhl p 5a Delta(94-113, 175-198) showed strongly diminished IgE binding in membrane blot and IgE-inhibition assays. Both deletions affect predominantly alpha-helical regions located in the N- and C-terminal halves of Phl p 5a, respectively. Whereas deletion of Delta175-198 alone was sufficient to cause a large reduction of the IgE reactivity in a subgroup of allergic sera, only the combination of both deletions was highly effective for all the sera tested. rPhl p 5a Delta(94-113, 175-198) consistently showed at least an 11.5-fold reduced capacity to activate basophils compared with the recombinant wild-type molecule, and the T cell proliferation assays demonstrated retention of T cell reactivity.

CONCLUSION

The mutant rPhl p 5a Delta(94-113, 175-198) fulfils the basic requirements for a hypoallergenic molecule suitable for a future immunotherapy of grass pollen allergy; it offers substantially reduced IgE binding and maintained T cell reactivity.

Natural and recombinant molecules of the cherry allergen Pru av 2 show diverse structural and B cell characteristics but similar T cell reactivity

BACKGROUND

Cherry allergy is often reported in the context of allergy to other fruits of the Rosaceae family and pollinosis to trees because of cross-reactive allergens. Allergic reactions to cherry are reported by 19-29% of birch pollen-allergic patients. Pru av 2, identified as a thaumatin-like protein (TLP) from sweet cherry, was recognized by the majority of cherry-allergic patients in immunoblotting.

OBJECTIVES

In order to investigate the structural characteristics and the immunoglobulin (Ig)E- and T cell reactivity of cherry-derived TLP, recombinant Pru av 2 was expressed in Escherichia coli and natural Pru av 2 was purified.

METHODS

Parallel-His and FLAG expression vectors were used for recombinant production of Pru av 2 in the cytoplasm and the periplasm of E. coli. Natural Pru av 2 was purified from fresh cherries and verified by N-terminal sequencing. Structural characterization was performed using circular dichroism (CD) measurements, and the biologic activity was measured in a glucanase assay. Using cherry-specific sera, the IgE-binding ability of recombinant and natural Pru av 2 was investigated in IgE-ELISA and the T cell reactivity was studied in proliferation assays. Results Natural Pru av 2 revealed thaumatin-like structural features and bound IgE of 50% of cherry-allergic patients. It was demonstrated to be enzymatically active. Recombinant Pru av 2 expressed in the cytoplasm of E. coli exhibited a slightly different folding compared with the natural protein. It was not recognized by IgE from cherry-allergic subjects, but retained the ability to stimulate T lymphocytes. Periplasmic recombinant Pru av 2 was able to bind an anti-grape TLP antibody and cherry-specific IgE.

CONCLUSIONS

We prepared two recombinant model TLPs from cherry, and compared their molecular characteristics as well as their IgE-binding activity and T cell interactions in relation to the natural counterpart. The cytoplasmic recombinant Pru av 2 can be used as a hypoallergenic variant in allergen-specific immunotherapy, whereas the periplasmic protein can be included in a component-resolved diagnosis.

Determination and refinement of the canine parvovirus empty-capsid structure

The canine parvovirus (CPV) empty-capsid structure has been determined and refined to 3.0 A resolution in the tetragonal space group P4(3)2(1)2 with cell dimensions a = b = 254.5 and c = 795.0 A. The successful structure determination shows that reasonably good diffraction data were obtained in spite of the very long c axis. The structure was solved by molecular replacement using the electron density of CPV full particles in a monoclinic space group. The phases were refined by non-crystallographic symmetry averaging. The structure refinement was carried out by using the programs PROLSQ and X-PLOR. The final R factor for the structure that included 85 water molecules per icosahedral asymmetric unit was 21.1% for reflections between 6.0 and 3.0 A resolution with an r.m.s. deviation of bond lengths of 0.020 A from ideal values. The structure of CPV empty capsids showed conformational differences with respect to full capsids at a region where icosahedrally ordered DNA in full particles interacts with the capsid protein. It also confirmed the absence of density along the fivefold axis in the CPV empty-particle structure in contrast to the situation in CPV full particles.