Cynodon
Poaceae
Desensitization, Immunologic
Rhinitis, Allergic, Seasonal
Allergens
The cross-reactive calcium-binding pollen allergen, Phl p 7, reveals a novel dimer assembly. (1/41)
The timothy grass pollen allergen Phl p 7 assembles most of the IgE epitopes of a novel family of 2 EF-hand calcium-binding proteins and therefore represents a diagnostic marker allergen and vaccine candidate for immunotherapy. Here we report the first three-dimensional structure of a representative of the 2 EF-hand allergen family, Phl p 7, in the calcium-bound form. The protein occurs as a novel dimer assembly with unique features: in contrast to well known EF-hand proteins such as calmodulin, parvalbumin or the S100 proteins, Phl p 7 adopts an extended conformation. Two protein monomers assemble in a head-to-tail arrangement with domain-swapped EF-hand pairing. The intertwined dimer adopts a barrel-like structure with an extended hydrophobic cavity providing a ligand-binding site. Calcium binding acts as a conformational switch between an open and a closed dimeric form of Phl p 7. These findings are interesting in the context of lipid- and calcium-dependent pollen tube growth. Furthermore, the structure of Phl p 7 allows for the rational development of vaccine strategies for treatment of sensitized allergic patients. (+info)Matua bromegrass hay for mares in gestation and lactation. (2/41)
Matua bromegrass hay (Bromus willdenowii Kunth) is a high quality forage, but its value for mares during gestation and lactation is not well known. Intake, rate of passage, performance, and reproduction by gestating and lactating Quarter Horse mares fed the hay was investigated. In this experiment, 12, 2- to 12-yr-old gravid mares (mean BW = 553 kg, SD = 36) were fed Matua hay (CP = 11.5%) or alfalfa hay (Medicago sativa L.) (CP = 15.4%) for variable days prepartum (mean 59.9 d; SD = 23.5) and for 70 d postpartum. Matua and alfalfa hay were fed as the roughage portion of the diet with a grain supplement. Mares, blocked by age, expected date of foaling, and BW, were assigned randomly within blocks to treatments (six mares per treatment). Forage type did not affect intake, gestation length, birth weight, number of foals, foal weight gain, day of first postpartum ovulation, cycles per conception, or pregnancy rate at 70 d. On d 1, milk from mares fed alfalfa hay contained less (P < 0.03) CP than milk from mares fed Matua hay. Milk CP decreased (P < 0.01) in all mares over time. In a separate experiment, voluntary intake and rate of passage of Matua (CP = 15.5%), alfalfa (CP = 24.9%), and Timothy (Phleum pratense L.) (CP = 4.1%) hays were determined in nine 2-yr-old pregnant mares (mean BW = 447 kg; SD = 21). Diets were 100% forage. Timothy hay did not meet CP requirements for mares. Voluntary intake of alfalfa hay was higher (P < 0.01) than Matua hay. Intake of Timothy hay was lower (P < 0.01) than the mean of alfalfa and Matua hay. Rate of passage offorage was measured by passage of Cr-mordanted fiber. Passage rate and retention time did not differ between Matua and alfalfa hay; however, the retention times of Matua and alfalfa hays were shorter (P < 0.01) than for Timothy hay. Our results indicate that Matua hay is a forage that can be used safely for mares during gestation and early lactation and for their young foals. (+info)Diurnal variation in uptake and xylem contents of inorganic and assimilated N under continuous and interrupted N supply to Phleum pratense and Festuca pratensis. (3/41)
Compensation by dark-period uptake of NH(4)(+) and NO(3)(-) in the grasses Phleum pratense L. and Festuca pratensis Huds. following N deprivation during the preceding light period was investigated in flowing solution culture under an artificial 10/14 h light/dark cycle. N was supplied as either NO(3)(-), NH(4)(+) or NH(4)NO(3) at 20+/-5 mmol m(-3), available continuously or only during the dark period, for 5-10 d. Intermittent N supply did not affect total daily N uptake, growth rate or net partitioning of dry matter. Net uptake and influx of NO(3)(-) varied similarly throughout the diurnal cycle when NO(3)(-) was supplied continuously, with a marginal contribution by NO(3)(-) efflux. Influx was significantly higher and efflux slightly higher following interruption of NO(3)(-) supply during the light period. Nitrate accounted for 80% of N in xylem exudate except between hours 6-9 of the light period when the amino acid concentration increased 3-fold, primarily as glutamine. Diurnal variation in relative NO(3)(-) uptake exhibited five phases of constant acceleration/deceleration, described reasonably well assuming NO(3)(-) influx was subject to metabolic co-regulation by NO(3)(-) and amino acid levels in the cytoplasmic compartment of the roots. Accordingly, influx is determined by variation in root NO(3)(-) levels throughout the dark period and the first half of the light period, but is down-regulated by increased amino acid levels during the second half of the light period. The sharp light/dark transitions affect transpiration rate and hence xylem N flux which, in turn, affect NO(3)(-) levels in the cytoplasmic compartment of the roots and the rate of NO(3)(-) assimilation in the shoot. (+info)Hypoallergenic derivatives of major grass pollen allergens for allergy vaccination. (4/41)
Grass pollen-induced hay-fever and allergic asthma represent a major health problem in industrialized countries. Whereas the symptoms of these allergic conditions can be controlled by pharmacotherapy, specific immunotherapy vaccination is the only causative approach towards the treatment of these type 1 allergies. Specific immunotherapy is based on administration of increasing amounts of the disease-causing allergens in the form of allergen-containing extracts. However, the extracts used for immunotherapy consist of allergenic and non-allergenic components and may induce severe anaphylactic side-effects upon therapeutic administration. With recent developments in molecular biology of pollen allergens it has become feasible to produce modified hypoallergenic derivatives of recombinant allergens with abrogated or greatly reduced likelihood of anaphylactic side-effects as compared to extract-based treatments. We have demonstrated this concept through reducing the anaphylactic potential of major rye grass pollen allergens by introducing a few point mutations which leave the overall structural fold of the molecule unaltered. These modified forms are expected to make allergen-specific immunotherapy more widely used in the future. (+info)Evaluation of CD4+ T cells proliferating to grass pollen in seasonal allergic subjects by flow cytometry. (5/41)
Our objective was to characterize T-cell responses to Phleum pratense in grass pollen allergic individuals and healthy controls using the fluorescent dye PKH26. Peripheral blood mononuclear cells were stimulated with P. pratense, or with recall antigens, and CD3+/CD4+ and CD3+/CD8+ T-cells that had proliferated were analysed by flow cytometry. In the presence of P. pratense CD4+/CD3+ T-cells proliferated more in grass pollen sensitive atopic patients than in nonallergic controls or in nongrass pollen sensitive atopic subjects. PPD and TT recall antigens elicited uniformly high proliferation in all T-cell subsets. Only half of pollen sensitive patients also had an increased proliferation of CD3+/CD8+ T-cells in response to P. pratense. We determined precursor frequency of CD4+ T cells in the original population that responded to P. pratense and found values ranging from 1 x 10-3 to 0.6 x 10-1, in the same range as those measured for PPD and TT. In conclusion, grass pollen sensitive atopic patients show enhanced CD4+ T-cell reactivity to P. pratense, and this could be related to the presence of elevated numbers of circulating allergen-specific CD4+ T cells. This flow cytometric method should allow the identification of other phenotypic markers such as intracellular cytokines in allergen specific responding CD4+ T cells. (+info)Oxygen deficiency affects carbohydrate reserves in overwintering forage crops. (6/41)
Anaerobic conditions developing under an ice cover affect winter survival and spring regrowth of economically important perennial crops. The objective was to compare, during a prolonged period of low (<2%) O2 at low temperature, the concentration of carbohydrates of four plant species contrasting in their resistance to oxygen deficiency. Four perennial forage species, lucerne (Medicago sativa L.), red clover (Trifolium pratense L.), timothy (Phleum pratense L.), and cocksfoot (Dactylis glomerata L.) were subjected to a progressively developing oxygen deficiency stress by enclosing potted plants in gas-tight bags in late autumn for overwintering in an unheated greenhouse. Timothy was previously reported to be more resistant to oxygen deficiency than the three other species. Non-structural carbohydrates increased and remained at a higher concentration in timothy than in the other three species under low O2 concentration. Concentrations of sucrose, fructose, glucose, and fructans increased in response to oxygen deficiency in timothy, whereas the concentration of soluble sugars decreased under the same conditions in lucerne, red clover, and cocksfoot. The gene expression of glyceraldehyde-3-phosphate dehydrogenase increased in response to low oxygen concentration in oxygen deficiency-sensitive lucerne while it remained unchanged in the oxygen deficiency-resistant timothy. It is concluded that timothy maintains higher carbohydrate reserves under oxygen deficiency, a specific feature that could favour its winter survival and spring regrowth. (+info)Grass pollen immunotherapy induces mucosal and peripheral IL-10 responses and blocking IgG activity. (7/41)
T regulatory cells and IL-10 have been implicated in the mechanism of immunotherapy in patients with systemic anaphylaxis following bee stings. We studied the role of IL-10 in the induction of clinical, cellular, and humoral tolerance during immunotherapy for local mucosal allergy in subjects with seasonal pollinosis. Local and systemic IL-10 responses and serum Ab concentrations were measured before/after a double-blind trial of grass pollen (Phleum pratense, Phl P) immunotherapy. We observed local increases in IL-10 mRNA-positive cells in the nasal mucosa after 2 years of immunotherapy, but only during the pollen season. IL-10 protein-positive cells were also increased and correlated with IL-10 mRNA(+) cells. These changes were not observed in placebo-treated subjects or in healthy controls. Fifteen and 35% of IL-10 mRNA signals were colocalized to CD3(+) T cells and CD68(+) macrophages, respectively, whereas only 1-2% of total CD3(+) cells and 4% of macrophages expressed IL-10. Following immunotherapy, peripheral T cells cultured in the presence of grass pollen extract also produced IL-10. Immunotherapy resulted in blunting of seasonal increases in serum allergen Phl p 5-specific IgE, 60- to 80-fold increases in Phl p 5-specific IgG, and 100-fold increases in Phl p 5-specific IgG4. Post-immunotherapy serum exhibited inhibitory activity, which coeluted with IgG4, and blocked IgE-facilitated binding of allergen-IgE complexes to B cells. Both the increases in IgG and the IgG "blocking" activity correlated with the patients' overall assessment of improvement. Thus, grass pollen immunotherapy may induce allergen-specific, IL-10-dependent "protective" IgG4 responses. (+info)Generation of an allergy vaccine by disruption of the three-dimensional structure of the cross-reactive calcium-binding allergen, Phl p 7. (8/41)
The grass pollen allergen, Phl p 7, belongs to a family of highly cross-reactive calcium-binding pollen allergens. Because Phl p 7 contains most of the disease-eliciting epitopes of pollen-derived calcium-binding allergens, hypoallergenic variants were engineered according to the x-ray crystal structure of Phl p 7 for allergy vaccination. In three recombinant variants, amino acids essential for calcium binding were mutated, and two peptides comprising the N- and C-terminal half were obtained by synthetic peptide chemistry. As determined by circular dichroism analysis and size exclusion chromatography coupled to mass spectrometry, recombinant mutants showed altered structural fold and lacked calcium-binding capacity, whereas the two synthetic peptides had completely lost their structural fold. Allergic patients' IgE Ab binding was strongest reduced to the variant containing two mutations in each of the two calcium-binding sites and to the peptides. Basophil histamine release and skin test experiments in allergic patients identified the peptides as the vaccine candidates with lowest allergenic activity. Immunization of rabbits with the peptides induced IgG Abs that blocked allergic patients' IgE binding to Phl p 7 and inhibited allergen-induced basophil degranulation. Our results indicate that disruption of an allergen's three-dimensional structure represents a general strategy for the generation of hypoallergenic allergy vaccines, and demonstrate the importance of allergen-specific IgG Abs for the inhibition of immediate allergic symptoms. (+info)"Phleum" is the genus name for a group of plants commonly known as Timothy-grass or Cat's-tail. It is a type of grass that is widely used in agriculture and gardening. I believe you might be looking for a medical term related to "phleum," so let me clarify:
In medical terminology, the term "phleum" is not commonly used. However, if you are referring to "phlebothrombosis," it is a term that could be relevant. Phlebothrombosis refers to the formation of a blood clot (thrombus) within a vein, which can occur due to various medical conditions or situations, such as immobility, surgery, or certain diseases. The term "phlebo-" means vein, and "-thrombosis" refers to the formation of a thrombus or blood clot.
If this is not the term you were looking for, please provide more context or clarify your question so I can give you a more accurate answer.
"Cynodon" is a term used in the field of veterinary medicine, specifically in the identification and classification of various species. It refers to a genus of warm-season, perennial grasses that are native to tropical and temperate regions around the world. The name "Cynodon" comes from the Greek words "kyon," meaning dog, and "odous," meaning tooth, which is a reference to the sharp, tooth-like spikes found on some of the species' leaves.
One of the most well-known species in this genus is Cynodon dactylon, also known as Bermuda grass. This hardy and adaptable grass is commonly used for lawns, golf courses, and other landscaping purposes due to its ability to withstand heavy foot traffic and maintain a lush, green appearance even in hot and dry conditions.
While "Cynodon" itself is not a medical term, it is important for veterinarians and other animal health professionals to be familiar with this genus of grasses, as they can have an impact on the health and well-being of animals that come into contact with them. For example, some species of Cynodon can cause skin irritation or allergic reactions in certain animals, while others may contain toxic compounds that can be harmful if ingested.
Overall, "Cynodon" is a term that is primarily used by veterinarians and other professionals in the field of animal health and care, rather than by medical doctors who treat humans.
Pollen, in a medical context, refers to the fine powder-like substance produced by the male reproductive organ of seed plants. It contains microscopic grains known as pollen grains, which are transported by various means such as wind, water, or insects to the female reproductive organ of the same or another plant species for fertilization.
Pollen can cause allergic reactions in some individuals, particularly during the spring and summer months when plants release large amounts of pollen into the air. These allergies, also known as hay fever or seasonal allergic rhinitis, can result in symptoms such as sneezing, runny nose, congestion, itchy eyes, and coughing.
It is important to note that while all pollen has the potential to cause allergic reactions, certain types of plants, such as ragweed, grasses, and trees, are more likely to trigger symptoms in sensitive individuals.
Poaceae is not a medical term but a taxonomic category, specifically the family name for grasses. In a broader sense, you might be asking for a medical context where knowledge of this plant family could be relevant. For instance, certain members of the Poaceae family can cause allergies or negative reactions in some people.
In a medical definition, Poaceae would be defined as:
The family of monocotyledonous plants that includes grasses, bamboo, and sedges. These plants are characterized by narrow leaves with parallel veins, jointed stems (called "nodes" and "internodes"), and flowers arranged in spikelets. Some members of this family are important food sources for humans and animals, such as rice, wheat, corn, barley, oats, and sorghum. Other members can cause negative reactions, like skin irritation or allergies, due to their silica-based defense structures called phytoliths.
Desensitization, Immunologic is a medical procedure that aims to decrease the immune system's response to an allergen. This is achieved through the controlled exposure of the patient to gradually increasing amounts of the allergen, ultimately leading to a reduction in the severity of allergic reactions upon subsequent exposures. The process typically involves administering carefully measured and incrementally larger doses of the allergen, either orally, sublingually (under the tongue), or by injection, under medical supervision. Over time, this repeated exposure can help the immune system become less sensitive to the allergen, thereby alleviating allergic symptoms.
The specific desensitization protocol and administration method may vary depending on the type of allergen and individual patient factors. Immunologic desensitization is most commonly used for environmental allergens like pollen, dust mites, or pet dander, as well as insect venoms such as bee or wasp stings. It is important to note that this procedure should only be performed under the close supervision of a qualified healthcare professional, as there are potential risks involved, including anaphylaxis (a severe and life-threatening allergic reaction).
Allergic rhinitis, seasonal (also known as hay fever) is a type of inflammation in the nose which occurs when an individual breathes in allergens such as pollen or mold spores. The immune system identifies these substances as harmful and releases histamine and other chemicals, causing symptoms such as sneezing, runny or stuffy nose, red, watery, and itchy eyes, cough, and fatigue. Unlike perennial allergic rhinitis, seasonal allergic rhinitis is worse during specific times of the year when certain plants pollinate.
An allergen is a substance that can cause an allergic reaction in some people. These substances are typically harmless to most people, but for those with allergies, the immune system mistakenly identifies them as threats and overreacts, leading to the release of histamines and other chemicals that cause symptoms such as itching, sneezing, runny nose, rashes, hives, and difficulty breathing. Common allergens include pollen, dust mites, mold spores, pet dander, insect venom, and certain foods or medications. When a person comes into contact with an allergen, they may experience symptoms that range from mild to severe, depending on the individual's sensitivity to the substance and the amount of exposure.
An antigen is any substance that can stimulate an immune response, leading to the production of antibodies or activation of immune cells. In plants, antigens are typically found on the surface of plant cells and may be derived from various sources such as:
1. Pathogens: Plant pathogens like bacteria, viruses, fungi, and oomycetes have unique molecules on their surfaces that can serve as antigens for the plant's immune system. These antigens are recognized by plant pattern recognition receptors (PRRs) and trigger an immune response.
2. Endogenous proteins: Some plant proteins, when expressed in abnormal locations or quantities, can be recognized as foreign by the plant's immune system and elicit an immune response. These proteins may serve as antigens and are involved in self/non-self recognition.
3. Glycoproteins: Plant cell surface glycoproteins, which contain carbohydrate moieties, can also act as antigens. They play a role in plant-microbe interactions and may be recognized by both the plant's immune system and pathogens.
4. Allergens: Certain plant proteins can cause allergic reactions in humans and animals when ingested or inhaled. These proteins, known as allergens, can also serve as antigens for the human immune system, leading to the production of IgE antibodies and triggering an allergic response.
5. Transgenic proteins: In genetically modified plants, new proteins introduced through genetic engineering may be recognized as foreign by the plant's immune system or even by the human immune system in some cases. These transgenic proteins can serve as antigens and have been a subject of concern in relation to food safety and potential allergies.
Understanding plant antigens is crucial for developing effective strategies for plant disease management, vaccine development, and improving food safety and allergy prevention.
Immunoglobulin E (IgE) is a type of antibody that plays a key role in the immune response to parasitic infections and allergies. It is produced by B cells in response to stimulation by antigens, such as pollen, pet dander, or certain foods. Once produced, IgE binds to receptors on the surface of mast cells and basophils, which are immune cells found in tissues and blood respectively. When an individual with IgE antibodies encounters the allergen again, the cross-linking of IgE molecules bound to the FcεRI receptor triggers the release of mediators such as histamine, leukotrienes, prostaglandins, and various cytokines from these cells. These mediators cause the symptoms of an allergic reaction, such as itching, swelling, and redness. IgE also plays a role in protecting against certain parasitic infections by activating eosinophils, which can kill the parasites.
In summary, Immunoglobulin E (IgE) is a type of antibody that plays a crucial role in the immune response to allergens and parasitic infections, it binds to receptors on the surface of mast cells and basophils, when an individual with IgE antibodies encounters the allergen again, it triggers the release of mediators from these cells causing the symptoms of an allergic reaction.