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At least 775 records · Page 43Linked to original sources
PubMed2001

Involvement of nitric oxide in pollen-induced biphasic nasal blockage in sensitised guinea pigs.

We have developed a reproducible allergic rhinitis model showing biphasic nasal blockage on repetitive inhalation challenge with Japanese cedar pollen in sensitised guinea pigs. The role of nitric oxide (NO) in inducing nasal blockage was evaluated with this model. N(omega)-nitro-L-arginine methyl ester (L-NAME), a non-selective NO synthase (NOS) inhibitor, intravenously administered before the challenge, significantly inhibited both early and late nasal blockage by approximately 80% and 50%, respectively. When L-NAME treatment was performed after the challenge, the late response was inhibited by approximately 70%. This inhibition was completely reversed by co-administration of L-arginine. However, aminoguanidine and L-N(6)-(1-iminoethyl)lysine, selective inhibitors of inducible NOS, negligibly influenced the degree of nasal blockage. Meanwhile, the alpha-adrenergic agonist, naphazoline, strongly suppressed both early and late nasal blockage. These results indicate that NO, likely produced by constitutive rather than inducible NOS, plays a major role in the occurrence of biphasic nasal blockage, primarily by inducing vasodilatation.

Administration, Intranasal↗
PubMed1995

Genetic Evidence for a Long-Range Activity That Directs Pollen Tube Guidance in Arabidopsis.

The fertilization process of plants is governed by different kinds of cell-cell interactions. In higher plants, these interactions are required both for recognition of the pollen grain by the female reproductive system and to direct the growth of the pollen tube inside the ovary. Despite many years of study, the signaling mechanisms that guide the pollen tube toward its target, the ovule, are largely unknown. Two distinct types of principles, mechanical and chemotropic, have been suggested to account for the directed growth of the pollen tube. The first of these two types of models implies that the guidance of the pollen tube depends on the architecture and chemical properties of the female reproductive tissues, whereas the latter suggests that the ovule provides a signal for the target-directed growth of the pollen tube. To examine such a role for the ovules, we analyzed the growth path of pollen tubes in mutants defective in ovule development in Arabidopsis. The results presented here provide unique in vivo evidence for an ovule-derived, long-range activity controlling pollen tube guidance. A morphological comparison of the ovule mutants used in this study indicates that within the ovule, the haploid embryo sac plays an important role in this long-range signaling process.

Journal Article↗
PubMed2003

Transcriptional profiling of Arabidopsis tissues reveals the unique characteristics of the pollen transcriptome.

Pollen tubes are a good model for the study of cell growth and morphogenesis because of their extreme elongation without cell division. Yet, knowledge about the genetic basis of pollen germination and tube growth is still lagging behind advances in pollen physiology and biochemistry. In an effort to reduce this gap, we have developed a new method to obtain highly purified, hydrated pollen grains of Arabidopsis through flowcytometric sorting, and we used GeneChips (Affymetrix, Santa Clara, CA; representing approximately 8,200 genes) to compare the transcriptional profile of sorted pollen with those of four vegetative tissues (seedlings, leaves, roots, and siliques). We present a new graphical tool allowing genomic scale visualization of the unique transcriptional profile of pollen. The 1,584 genes expressed in pollen showed a 90% overlap with genes expressed in these vegetative tissues, whereas one-third of the genes constitutively expressed in the vegetative tissues were not expressed in pollen. Among the 469 genes enriched in pollen, 162 were selectively expressed, and most of these had not been associated previously with pollen. Their functional classification reveals several new candidate genes, mainly in the categories of signal transduction and cell wall biosynthesis and regulation. Thus, the results presented improve our knowledge of the molecular mechanisms underlying pollen germination and tube growth and provide new directions for deciphering their genetic basis. Because pollen expresses about one-third of the number of genes expressed on average in other organs, it may constitute an ideal system to study fundamental mechanisms of cell biology and, by omission, of cell division.

Arabidopsis↗
PubMed1999

Pollen-stigma adhesion in Arabidopsis: a species-specific interaction mediated by lipophilic molecules in the pollen exine.

To investigate the nature and role of cell adhesion in plants, we analyzed the initial step of pollination in Arabidopsis: the binding of pollen grains to female stigma cells. Here we show this interaction occurs within seconds of pollination. Because it takes place prior to pollen hydration, it also requires adhesion molecules that can act in a virtually dry environment. We developed assays that monitored adhesion of populations of pollen grains and individual cells. Adhesion between pollen and stigma cells is highly selective - Arabidopsis pollen binds with high affinity to Arabidopsis stigmas, while pollen from other species fails to adhere. Initial binding is independent of the extracellular pollen coat (tryphine), indicating that adhesion molecules reside elsewhere on the pollen surface, most likely within the exine walls. Immediately after pollination, the stigma surface becomes altered at the interface, acquiring a pattern that interlocks with the exine; this pattern is evident only with pollen from Arabidopsis and its close relatives. Purified exine fragments bind to stigma cells, and biochemical analyses indicate that this specific, rapid and anhydrous adhesion event is mediated by lipophilic interactions.

Arabidopsis↗
PubMed1999

[Effectiveness of Nd: YAG laser therapy on Japanese cedar pollinosis].

Many have reported on the effectiveness of laser surgery therapy for perennial allergic rhinitis. However, the suppressive effects of laser irradiation on allergic rhinitis and its symptoms have not been reported in patients with pollinosis. This is because therapeutic effects on pollinosis are difficult to evaluate. The amount of pollen in the air varies during the year, and from year to year. Also, allergic symptoms develop due to exposure to the amount of pollen which is markedly influenced by the weather. In this study, the severity of allergic symptoms in the pollen season was compared between patients treated with early medication, non-treated patients and patients treated with preseasonal contact Nd: YAG laser surgery. Results suggests that laser surgery was effective in reducing the severity of symptoms in patients with cedar pollinosis. Symptoms were milder in the laser group than in the medication group and non-treated group for 3-4 weeks after the start of seasonal pollinosis, although no differences were noted in the early weeks. This may be explained by the fact that laser irradiation reduces the lamina propria of the nasal mucosa, the site of allergic reactions. This also suggests that allergic pollen can't penetrate the mucosal surface which shows squamous epithelization after laser irradiation.

Adult↗
PubMed1997

[Eosinophilic gastroenteritis caused by bee pollen sensitization].

A 34-year-old Spanish woman with a lifelong history of seasonal rhinoconjunctivitis and honey intolerance (pyrosis and abdominal pain) developed, 3 weeks after starting ingestion of bee pollen, astenia, anorexia, abdominal pain, diarrhoea, peripheral blood hypereosinophilia and elevated serum total IgE levels. A duodenal biopsy showed eosinophilic infiltration of the mucosal layer. Other causes of hypereosinophilia were not found. Repeated parasitological stool studies, as well as a duodenal aspirate showed negative results. Symptoms, hypereosinophilia and elevated IgE levels resolved after bee pollen ingestion was stopped. This is a typical case of eosinophilic gastroenteritis by ingestion of bee pollen in a woman with intolerance to honey bee, because the patient fulfilled the usual diagnostic criteria: gastrointestinal symptoms were present, eosinophilic infiltration of the digestive tract was demonstrated by biopsy, no eosinophilic infiltration of other organs was found and the presence of parasites was excluded. Honey intolerance and/or bee pollen administration should be considered as a cause of eosinophilic gastroenteritis.

Adult↗
PubMed1992

[An enzyme-linked immunosorbent assay for the quantitation of the major allergen from Japanese cedar (Cryptomeria japonica) pollen, Cry j I, using monoclonal antibodies].

We have developed an enzyme-linked immunosorbent assay (ELISA) using two anti-Cry j I monoclonal antibodies (KW-S10 and KW-S131) for the quantitation of the major allergen from Japanese cedar (Cryptomeria Japonica) pollen, Cry j I. Polystyrene microplates coated with KW-S131 were incubated with pollen allergen extracts. Cry j I, which bound to the antibody, was detected with alkaline phosphatase-conjugated KW-S10 using chromogenic enzyme substrate. Cry j I could be measured in concentration of between 0.16 and 2.5 ng/ml by this assay. Intra- and inter-assay coefficients of variation were 1.1-3.5% and 0.9-4.6%, respectively. This assay was considered that it was specific for Cry j I of Japanese cedar pollen because it didn't react with allergens of hinoki (Chamaecypairs obtusa) pollen which have antigenicity in common to Japanese cedar pollen. This assay would be useful for the standardization of Japanese cedar pollen allergen extracts.

Allergens↗
PubMed1991

Pollen sensitization and allergy in children depend on the pollen load.

We investigated the influence of grass and birch pollen load on specific IgE response, skin prick test reactivity, and manifest allergic disorders of the eyes and respiratory tract. The study population was two groups of 200 children each, matched in sex and age, who were domiciled in areas with high and low pollen load, respectively. In the children from the area with high pollen load, the grass pollen load was 1.7 times higher than in the other and only specific IgE to grass pollen was found to be present more frequently (23.5% as against 12.5%; P less than 0.01). In the same area, the birch pollen load was 2.8 times higher, which caused specific IgE in 10.5% as against 3.5% of the other group (P less than 0.01) as well as positive skin prick test in 9.0% as against 3.5% (P less than 0.05). Reports of subjective complaints were rare among the group with high pollen load but the total number did not amount to a statistically significant increase. There was no difference between the two groups concerning sensitization and allergy to house dust mite. This suggests that the influence of the pollen load is strongest on the development of specific IgE, and less on skin test reactivity and manifest allergies.

Air Pollutants↗
PubMed1993

Seasonal allergic symptoms and their relation to pollen exposure in south-east France.

In order to evaluate the relationship between pollen exposure and prevalence of allergic respiratory symptoms, we performed a cross-sectional epidemiological study in 2 areas with contrasted exposure to cypress and grass pollens. The study population consisted of 5427 subjects 18 to 65-years-old representative of the general population. All answered an abridged version of the 1978 ATS questionnaire and a sample had a skin test evaluation including grass and cypress pollens. Prevalence of hay fever symptoms was equal to 31.5% and 14.1%, respectively, in exposed and less exposed community (P < 0.001). Prevalence of hay fever symptoms together with a positive skin test to pollen was also significantly higher in the exposed (13.6%) vs less exposed community (5.5%, P < 0.001). In contrast, overall prevalence of asthma was equal to 4.5% and 3.4%, respectively. Prevalence of asthma with positive skin tests was also not statistically significant, equal to 2.5% and 1.9%, respectively. Thus, high exposure to pollen is a risk factor for developing hay fever but not asthma.

Adolescent↗
PubMed1977

Induction of a ragweed-specific allergic state in Ir-gene-restricted nonresponder mice.

Mice of the inbred strains, C57BL/6 and C57BL/10 (H-2b), are genetically incapable of developing IgE antibody responses to ragweed pollen extract (RE) or its dinitrophenylated derivative, DNP-RE. This nonresponsiveness has previously been thought to reflect the absence of a relevant H-2-linked Ir genes controlling responses of inbred mice to these antigens. However, pretreatment of H-2b mice with either low doses of ionizing X irradiation or cyclophosphamide abrogates the nonresponder status of such animals, apparently by removal of a suppressive mechanism normally inhibiting development of IgE responses to these antigens. The implications of these findings for mechanisms of genetic control of IgE antibody synthesis and the Ir-gene concept are discussed.

Animals↗
PubMed2000

Morphometrics and adaptatives aspects in africanized honeybees (Apis mellifera).

The introduction of the African bees (Apis mellifera scutelata) in Brazil and their expansion in the American Continent created the opportunity to study the process of species adaptation in a new environment. In that process, within intra-specific variability, normalising selection can favour individuals that present a better adaptative morphology and they will constitute the most frequent type found in the population. To test that hypothesis morphometric analyses in samples of colonies of africanized bees and in samples of the populations were performed. The development of the colonies was also evaluated in terms of the amount of their brood, honey and pollen. Analysis of the data indicates that more developed colonies are formed by individuals closer to the population average with concerning morphological traits.

Journal Article↗
PubMed1988

A multicenter, open study of the non-sedating antihistamine, terfenadine (Seldane), in the maintenance therapy of seasonal allergic rhinitis.

A multicenter open study was conducted throughout the 1984 fall pollen season to assess the possible development of tolerance or loss of efficacy to terfenadine in the maintenance therapy of patients with seasonal pollinosis. Patients with proven allergic pollinosis were entered into a 1-week initial treatment period taking terfenadine 60 mg bid and only those who responded to the initial treatment with "moderate" to "complete" relief continued on terfenadine throughout a 4 to 11-week pollen season for evaluation of continued efficacy. A total of 179 patients from five study centers were enrolled in the initial treatment period and 154 (86%) responded to terfenadine with "moderate" to "complete" relief of symptoms. Of these 154 patients who continued terfenadine treatment, approximately 90% of the patients maintained the same degree of relief throughout the pollen season. All symptoms of seasonal pollinosis including nasal congestion improved significantly the first day of treatment. This improvement in symptoms continued during the first week and remained unabated throughout the pollen season. The incidence of adverse events was low with sedation being reported by only 2.8% of patients at some time point during the study. It is concluded that terfenadine is a safe and effective non-sedating antihistamine in the maintenance therapy of seasonal allergic pollinosis and that tolerance is not noted during continued administration.

Adult↗
PubMed2006

The gene responsible for borate cross-linking of pectin Rhamnogalacturonan-II is required for plant reproductive tissue development and fertilization.

Deficiencies in boron, a microelement that is essential for the growth and development of higher plants, often cause problems in reproductive growth. Rhamnogalacturonan-II (RG-II) in cell wall pectin acts as the sole receptor for boron in plant cells, forming a borate cross-linked RG-II dimer (dRG-II-B), but the physiological functions of dRG-II-B remain unknown. We have previously shown that the pectin glucuronyltransferase 1 gene NpGUT1, which is involved in the biosynthesis of RG-II sugar chains, is essential for the formation of the RG-II-B complex, resulting in tight intercellular attachment in meristematic tissues. Because NpGUT1 expression was found to be abundant in reproductive organs in addition to meristematic tissues, we analyzed the expression and functions of NpGUT1 in more detail in tobacco reproductive tissues. Specific NpGUT1 expression was detected in the tapetum of flower buds and in the pollen, pollen tube tips, and transmitting tissue of the pistils of flowers. Dexamethasone-induced expression of the NpGUT1 antisense gene in flower buds resulted in the formation of sterile flowers with aberrant development of pollen and transmitting tissue. Pollen tubes could not pass through pistils with aborted transmitting tissue, and expression of an NpGUT1 antisense gene in germinating pollen inhibited pollen tube elongation, accompanied by the absence of pectin RG-II and boron in the pollen tube tip. These results indicate that expression of NpGUT1 is required for the development and functions of male and female tissues.

Borates↗
PubMed2000

[Allergy to cypress pollen: preparation of a reference and standardization extract in vivo].

Development of Cypress allergy frequency led to the standardization of commercial cypress extract used for diagnosis and immunotherapy. Previous in vitro studies on two cypress pollen species (Cupressus sempervirens and Cupressus arizonica) allowed us to produce an allergenic solution composed by a mixture of both extracts for in vivo standardization. Dilutions of this allergenic solution were tested by prick-test on 44 patients with clinical allergy to cypress pollen to define the dilution that corresponds to a 6 mm wheal conformed to the definition of 100 IR. The mixture of the two major species found in France is justified by the in vitro study results. Extracts revealed complementary allergenic composition: Cup sempervirens showed a wider diversity of allergens whereas Cup arizonica showed a higher content of the major 43 kDa allergen. Thus, according to in vivo analysis, we are able to produce a standardized extract of Cypress pollen expressed in IR.

Adult↗
PubMed2002

Prevalence of occupational allergy to Chrysanthemum pollen in greenhouses in the Netherlands.

BACKGROUND: An increasing number of allergic complaints appear to have occurred among Chrysanthemum greenhouse employees. The aim of this study was to estimate the prevalence of work-related allergic symptoms and the prevalence of sensitization to pollen of different members of the Chrysanthemum family. METHODS: We studied 104 employees who were invited to answer an extensive questionnaire and to complete a rhinitis quality of life questionnaire. In addition, they were skin prick tested on location with inhalant allergens and home-made pollen extracts of seven different members of the Chrysanthemum family. Radio-allergo-sorbent tests were performed to confirm IgE-mediated reactions. RESULTS: Work-related symptoms were reported in 56.7% of all cases, with the main symptom being rhinitis. Sensitization to Chrysanthemum pollen was found in 20.2% of the employees without one member of the Chrysanthemum family in particular being most prevalent. Sensitization to Chrysanthemum pollen was considered to be an important risk factor for the occurrence of work-related symptoms of the upper airways. Furthermore, inhalant atopy as well as sensitization to common airborne pollen including mugwort were closely associated with sensitization to Chrysanthemum what might be suggestive for cross-sensitization. CONCLUSIONS: There is a high prevalence of work-related symptoms in Chrysanthemum greenhouses. In one-third of the employees these symptoms were caused by an IgE-mediated allergy caused by the pollen of the flowers. Inhalant atopy appeared to have a great impact on the development of such a sensitization. Measurements to reduce the pollen exposure are necessary to prevent a further increase of this occupational allergy.

Adolescent↗
PubMed2006

Cytological mechanism of pollen abortion resulting from allelic interaction of F1 pollen sterility locus in rice (Oryza sativa L.).

Pollen abortion is one of the major reasons causing the inter-subspecific F(1) hybrid sterility in rice and is due to allelic interaction of F(1) pollen sterility genes. The microsporogenesis and microgametogenesis of Taichung 65 and its three F(1) hybrids were comparatively studied by using techniques of differential interference contrast microscopy, semi-thin section light microscopy, epifluorescence microscopy and TEM. The results showed that there were differences among the cytological mechanisms of pollen abortion due to allelic interaction at the three F(1) pollen sterility loci. The allelic interaction at S-a locus resulted in microspores unable to extend the protoplasm membrane with the enlargement of the microspore at the middle microspore stage and finally producing empty abortive pollen. The allelic interaction at S-b locus caused asynchronous development of microspores at the middle microspore stage producing stainable abortive pollen. The allelic interaction at S-c locus mainly led to the non-dissolution of the generative cell wall and finally caused the hybrid F(1) mainly producing stainable abortive pollen. Genotypic identification indicated that the abortive pollen were those with S ( j ) allele.

Alleles↗
PubMed2002

Rhinitis (allergic and nonallergic) in an atopic pediatric referral population in the grasslands of inland South Africa.

BACKGROUND: Allergic rhinitis is a common condition, which causes considerable morbidity. South African data are scarce. OBJECTIVE: We sought to describe allergic rhinitis in atopic children in inland South Africa. METHODS: An observational, descriptive study of rhinitis occurring in 771 new patients seen consecutively by a single observer at a referral pediatric allergy clinic (Universitas Hospital, Bloemfontein) over an 8 1/2-year period (August 1984 to March 1993) was carried out. A detailed questionnaire was used to record clinical data. Chest and sinus x-rays, skin prick testing, and radioallergosorbent test were performed, and serum immunoglobulin E levels were determined. Response to drug treatment regimens was recorded at subsequent followup visits. RESULTS: Significant rhinitis was reported in 78.1% of patients, and mild intermittent rhinitis was reported in 21.4%. Male to female ratio was 1.6:1. Median age at onset of rhinitis symptoms was 6 months (range 0 months to 12 years), with 30.1% experiencing symptoms from birth. Rhinitis was chronic in 61.3%, although 53.5% reported seasonal variation. More children with rhinitis were born in midsummer than during other seasons, although this did not reach statistical significance (P = 0.46). Breast-feeding had no protective effect, and parental smoking and household pets were not found to be risk factors. Family history was positive for allergic rhinitis in 88% of patients. Exposure to dust, weather changes, strong odors, pets, pollens, and tobacco smoke were the most common trigger factors. Sinus x-ray findings associated poorly with clinical findings. The most common allergens identified were grass pollen, tree pollen, and cat. Oral antihistamines provided good symptomatic relief in 62.9% of patients who used them. Intranasal corticosteroids provided good relief in 78.0% of those who used them, and ketotifen provided relief in 54.4% of those who used it. CONCLUSIONS: Rhinitis is a common manifestation of allergy in the population studied. Onset occurs early in childhood. A family history of allergy is a risk factor for the development of the condition, and grass pollen is the most common allergen involved. Special investigations are of limited value. Appropriate treatment is very effective.

Child↗
PubMed1989

The organization and expression of a maize ribosomal protein gene family.

We have isolated several Zea mays cDNAs encoding the 40S subunit ribosomal protein S14. In maize, this ribosomal protein is encoded by a small multigene family, at least three members of which are expressed. S14 transcript levels are highest in mitotically active tissues, such as seedling shoot, developing endosperm, and tassel primordia, and lowest in tissues with little cell division, such as mature leaf and root. Very little S14 RNA is present in pollen, suggesting that translation of pollen mRNAs during pollen germination uses preformed ribosomes. During kernel development, the highest levels of S14 transcripts in endosperm tissue are found at 10-12 days postpollination; S14 RNA levels decline continuously from this point onward. The period of maximal expression of the S14 ribosomal protein gene appears to precede the onset of storage protein synthesis and does not correlate with the reported times of increased nucleolar volume or genome amplification.

Blotting, Northern↗