PubMed Health⌕ Search

Biomedical subjects

B F Gibbs

Publications and source records attributed to B F Gibbs.

At least 37 records · Page 2Linked to original sources
PubMed2000

In vitro investigations with the histamine H1 receptor antagonist, epinastine (WAL 801 CL), on isolated human allergic effector cells.

OBJECTIVE AND DESIGN: Skin mast cells, basophils and eosinophils are effector cells of acute and subacute allergic responses due to their capacity to produce a large number of (pro)inflammatory mediators. Histamine H1 receptor antagonists, such as epinastine (WAL 801 CL), have been described to partially exert antiallergic and antiinflammatory effects both in vivo and in vitro in addition to their antihistaminergic properties. The aim of the present study was to investigate whether epinastine could influence the in vitro activation of isolated human skin mast cells, basophils and eosinophils induced by different secretagogues. METHODS: Cells were isolated from healthy women following plastic surgery and healthy blood donors, respectively. Mast cells were isolated by enzymatic digestion of the skin. Blood cells were isolated by gradient centrifugation and negative selection with magnetic beads. RESULTS: A wide range of concentrations of the drug (1 nmol/l to 100 micromol/l) did not significantly inhibit histamine release from basophils induced by immunologic (anti-IgE, concanavalin A, priming factors interleukin-3 and interleukin-5) and non immunologic (A23187, ionomycin, 12-o-tetradecanoyl-phorbol-13-acetate, C5a, formyl-methionyl-leucyl-phenylalanine) stimuli. Furthermore, the drug had no effect on A23187-induced release of eosinophil cationic protein from eosinophils. However, at a concentration >0.1 nmol/l, IgE-mediated LTC4 production from basophils was significantly suppressed. Histamine release from skin mast cells due to anti-IgE or A23187 was inhibited by epinastine in a dose-dependent fashion, whereas substance P-induced activation as well as stem cell factor priming were not. Epinastine did not inhibit isolated protein kinase C from rat brain. CONCLUSION: The results confirm previous in vivo and in vitro observations obtained from animal models that epinastine exerts antiallergic and antiinflammatory effects. Whether the observed effects are due to non specific membrane interactions or by influencing intracellular signal transduction elements has to be further elucidated.

Basophils↗
PubMed1999

Purification of morphologically and functionally intact human basophils to near homogeneity.

Certain studies on basophils require highly purified functionally intact cell preparations. Here, a three-step procedure is described that meets these requirements. The procedure consists of a Ficoll density gradient step, counterflow elutriation and negative selection by magnetic cell sorting (MACS). The mean purity of basophils obtained from 30 donors was 97.6+/-3.96% with a viability of 99.6+/-0.83%. The recovery rate was 49.7+/-15.6%. The cells had a normal morphological appearance as assessed by May-Grünwald-stained cytospins and were functionally intact as shown by their unaltered capacity to release histamine and interleukin 4 (IL-4) following immunological activation. This procedure is a clear improvement over currently available techniques and should facilitate future investigations on basophils.

Basophils↗
PubMed1999

Dietary lectins can induce in vitro release of IL-4 and IL-13 from human basophils.

Dietary lectins, present in beans and other edible plant products, pose a potential threat to consumers due to their capacity to induce histamine release from basophils. In this study, we analyzed the capacity of 16 common, in particular dietary, lectins to induce human basophils to secrete IL-4 and IL-13, the key promoters of Th2 responses and IgE synthesis. Several of the lectins, especially concanavalin A, lentil lectin, phytohemagglutinin, Pisum sativum agglutinin and Sambucus nigra agglutinin, triggered basophils to release IL-4 at concentrations of up to 1 ng/10(6) basophils. Lectins with high IL-4-inducing capacity also stimulated the release of IL-13 and histamine. Lectin-induced IL-4 and IL-13 release reached a maximum after 4-6 h and more than 18 h, respectively. Affinoblotting revealed that lectins with the capacity to induce mediator release bind to IgE, suggesting IgE binding as initial step of signal generation. In conclusion, several dietary lectins can trigger human basophils to release IL-4 and IL-13. Since lectins can enter the circulation after oral uptake, they might play a role in inducing the so-called early IL-4 required to switch the immune response towards a Th2 response and type I allergy.

Basophils↗
PubMed1999

Inhibitors of PI 3-kinase and MEK kinase differentially affect mediator secretion from immunologically activated human basophils.

Effects of inhibitors of PI 3-kinase and MEK kinases were investigated on histamine, leukotriene C4(LTC4), and cytokine release from human basophils stimulated with anti-IgE. The PI 3-kinase antagonists wortmannin (> 10 nM) and LY 294002 (>1 microM) strongly inhibited anti-IgE-induced release of all mediators by 40-100%. This was contrasted by the effects of the MEK kinase inhibitor PD 098059, which weakly inhibited histamine, interleukin (IL)-4, and IL-13 release but was substantially more efficacious at blocking LTC4 production (>70% at 10 microM). Previous studies have shown that arachidonic acid synthesis is controlled by MEK kinases. We observed that wortmannin, LY 294002, and PD 098059 reduce basophil ERK-1,2 activation, thus implying that, with regard to arachidonic acid metabolism, MEK kinases are a downstream target for PI-3-kinase. Our results demonstrate a universal regulatory role played by PI 3-kinases in basophil mediator production and release, whereas MEK kinase signaling is largely limited to controlling arachidonic acid metabolism.

Antibodies, Anti-Idiotypic↗
PubMed1999

Ambroxol inhibits the release of histamine, leukotrienes and cytokines from human leukocytes and mast cells.

OBJECTIVES AND DESIGN: The effects of the mucolytic agents ambroxol and N-acetylcystein (NAC) were studied on the release of histamine, leukotrienes, cytokines and superoxide anions from a variety of cells involved in the pathogenesis of allergic inflammation. SUBJECTS: Mast cells were isolated from human adenoids and skin (n = 5-6). Basophils, monocytes and granulocytes were obtained from Buffy-coat blood obtained from healthy blood donors (n = 4-7) and enriched by density centrifugation. TREATMENT AND METHODS: Ambroxol or NAC were added to the cells for different periods before stimulation with various immunological and non-immunological secretagogues. Histamine release from mast cells, basophils and monocytes was assayed either by radioimmunoassay or spectrofluorometrically. LTC4 (basophils), LTB4 (neutrophil/eosinophil granulocytes or monocytes), IL-4 and IL-13 (basophils) were measured by ELISA. RESULTS: Ambroxol inhibited histamine release by more than 50% from human adenoidal mast cells (1000 microM ambroxol) and skin mast cells (100 microM ambroxol) stimulated by Con A and compound 48/80, respectively. Ambroxol (100 microM) strikingly inhibited anti-IgE induced release of both histamine, LTC4, IL-4 and IL-13 from basophils and reduced both histamine and LTB4 release induced by C5a or Zymosan in monocytes. The drug also reduced LTB4 and superoxide anion production in granulocytes stimulated by zymosan or fMLP. In all cell types studied, ambroxol was more efficacious following a short preincubation (5-15 min) of the drug with the cells before stimulation. In contrast, NAC produced no clear effects on any of the different cell types studied, regardless of the preincubation period, the concentration or the stimulus employed. CONCLUSIONS: Unlike NAC, ambroxol is able to not only inhibit acute mediator release from mast cells and leukocytes but also reduce immunomodulatory cytokine generation from basophils and may have beneficial effects in the treatment of allergic respiratory diseases.

Ambroxol↗
PubMed1999

Enteral histaminosis: Clinical implications.

There is increasing evidence that enteral histaminosis is a major cause of food intolerance resulting from dysfunctional metabolism of endogenous histamine in certain food stuffs. However, this phenomenon has been poorly characterised and, due to the lack of epidemiological data, the existence of this condition has been underestimated, which may lead to incorrect diagnosis. This short commentary highlights a stricter regimen of diagnostic procedure in order to take into account the many causes of food intolerance. The underlying mechanisms ascribed particularly to non-immunologically food reactions require more rigorous research and further work is vital.

Clinical Protocols↗
PubMed1999

Encapsulation in the food industry: a review.

Encapsulation involves the incorporation of food ingredients, enzymes, cells or other materials in small capsules. Applications for this technique have increased in the food industry since the encapsulated materials can be protected from moisture, heat or other extreme conditions, thus enhancing their stability and maintaining viability. Encapsulation in foods is also utilized to mask odours or tastes. Various techniques are employed to form the capsules, including spray drying, spray chilling or spray cooling, extrusion coating, fluidized bed coating, liposome entrapment, coacervation, inclusion complexation, centrifugal extrusion and rotational suspension separation. Each of these techniques is discussed in this review. A wide variety of foods is encapsulated--flavouring agents, acids bases, artificial sweeteners, colourants, preservatives, leavening agents, antioxidants, agents with undesirable flavours, odours and nutrients, among others. The use of encapsulation for sweeteners such as aspartame and flavours in chewing gum is well known. Fats, starches, dextrins, alginates, protein and lipid materials can be employed as encapsulating materials. Various methods exist to release the ingredients from the capsules. Release can be site-specific, stage-specific or signalled by changes in pH, temperature, irradiation or osmotic shock. In the food industry, the most common method is by solvent-activated release. The addition of water to dry beverages or cake mixes is an example. Liposomes have been applied in cheese-making, and its use in the preparation of food emulsions such as spreads, margarine and mayonnaise is a developing area. Most recent developments include the encapsulation of foods in the areas of controlled release, carrier materials, preparation methods and sweetener immobilization. New markets are being developed and current research is underway to reduce the high production costs and lack of food-grade materials.

Capsules↗
PubMed1999

Early interleukin-4: its role in the switch towards a Th2 response and IgE-mediated allergy.

The etiology of IgE-mediated allergies is complex and, thus far, not completely understood. A common feature, however, is the overproduction of IgE-inducing cytokines, e.g. interleukin-4(IL-4), compared to IgE-antagonistic cytokines, such as interferon-gamma or IL-12. IgE-inducing cytokines are produced by T helper type 2 (Th2) cells. The differentiation of naive T cells towards the Th2 phenotype seems to be crucially dependent upon the particular cytokines present in the early stages of an immune response. Concerning the factors driving Th2 differentiation, the so-called 'early IL-4' seems to play an important role, although there is some controversy over the degree of its requirement and its cellular source. We have recently demonstrated that basophils might be such a source, since they rapidly release IL-4 upon antigen-specific or nonantigen-specific stimuli, such as certain lectins. This makes lectins interesting candidates for inducing a Th2 response and IgE-mediated allergy in unsensitized individuals.

Humans↗
PubMed1999

Proposing sequences for peptides derived from whey fermentation with potential bioactive sites.

In fed-batch fermentation by Kluyveromyces marxianus var. marxianus, whey-soluble proteins were converted into oligopeptides. To assess whether bioactive peptides could be produced during whey fermentation, K. marxianus was cultured in batch in deproteinized media containing 5 or 15% (wt/vol) dehydrated whey for 20 h and then was in fed-batch mode for 50 h. After harvesting the biomass (25,000 x g, 15 min), at 6-h intervals, the wort was analyzed to determine protein consumption and oligopeptide production by HPLC. The proteins in the wort showed an oscillatory degradation with a constant increase in the production of oligopeptides. Four major peaks were collected and were analyzed by API mass spectroscopy. Sequences of fermented peptides were compared with sequences of known bioactive peptides. On the basis of their molecular weights, two amino acid sequences were proposed. The presence of sites containing the peptide sequence of beta-lactorphin (YLLF) suggests that these oligopeptides may have antihypertensive properties.

Amino Acid Sequence↗
PubMed1999

Purification and identification of potentially bioactive peptides from enzyme-modified cheese.

Antihypertensive peptides inhibiting angiotensin I-converting enzyme have been isolated from enzymatic hydrolysates of various food materials, but no information is available on the isolation of antihypertensive peptides from enzyme-modified cheese. In this study, several bioactive peptides, mainly potential antihypertensive peptides from enzyme-modified cheese prepared by commercial and Lactobacillus casei enzymes, were purified and identified. Enzyme-modified cheese samples were prepared by combination of Neutrase (1883.0 U/ml), L. casei enzymes (amino peptidase activity 86.4 leucine aminopeptidase U/g), and Debitrase (22.0 leucine aminopeptidase U/g). The water-soluble fractions of the enzyme-modified cheeses that were prepared by different enzymes were subjected to reverse-phase HPLC on a Delta Pak C18 column. Each peak was purified on the same column using a binary gradient. One peak from the Neutrase digest, five peaks from the Neutrase-Debitrase digest, and two peaks from the Neutrase-Lactobacillus enzyme digest were purified and identified by API mass spectrometry. On the basis of their molecular masses, amino acid sequences of purified peptides were identified. beta-Casomorphin with a sequence like that of beta-casein (YPFPGPI f 60-66) was found after the Neutrase digest. All of the peptides purified from the digests with combination of Neutrase and Debitrase or Neutrase and L. casei enzymes contained active sites in their sequences. The presence of sites containing potential antihypertensive peptides suggests that the purified peptides may have antihypertensive properties. Thus, the enzyme-modified cheese process, mainly designed to produce flavor ingredients, may simultaneously produce bioactive peptides, which are considered to be of physiological importance.

Amino Acid Sequence↗
PubMed1998

Inhibition of interleukin-4 and interleukin-13 release from immunologically activated human basophils due to the actions of anti-allergic drugs.

Human basophils have recently been shown to rapidly produce and release interleukin (IL-)4 and IL-13 as well as histamine and eicosanoids. Since both IL-4 and IL-13 can initiate and maintain late phase allergic reactions we addressed whether some widely used anti-allergic drugs can inhibit the anti-IgE induced release of these cytokines from enriched human basophils. Basophils were enriched (47-92% purity) by Ficoll density centrifugation followed by elutriation and negative selection of contaminating cells using immunomagnetic beads. Basophils were stimulated with sub-optimal dilutions of anti-IgE in the presence or absence of various drugs and the release of histamine and cytokines were measured after 30 min and 4 h, respectively. The beta-2 agonist salmeterol, the H1-receptor antagonist terfenadine and the phosphodiesterase inhibitor theophylline inhibited the release of IL-4 and IL-13 by more than 50% following 4 h of basophil stimulation with anti-IgE. These drugs also inhibited the release of histamine following 30 min stimulation, although with less efficacy than for IL-4 and IL-13. Short preincubation of basophils with salmeterol or terfenadine before stimulation gave rise to significantly greater inhibition of histamine release but had less effect on the inhibition of cytokine release. The effects of theophylline, however, were not significantly affected by preincubation of the cells with the drug. In contrast to the aforementioned drugs, salbutamol and cetirizine were ineffective at inhibiting both histamine and cytokine release from basophils. These results suggest that a number of anti-allergic drugs may mediate their effects, in part, in reducing late phase allergic responses due to their actions on IL-4 and IL-13 secretion from basophils.

Adrenergic beta-Agonists↗
PubMed1997

Human lung mast cells release small amounts of interleukin-4 and tumour necrosis factor-alpha in response to stimulation by anti-IgE and stem cell factor.

Recent reports have suggested that mast cells are capable of producing and releasing a number of pro-inflammatory cytokines. However, these studies have mainly been carried out using murine tissue culture derived mast cells and it is known that these cells differ markedly in their functional properties from isolated human mast cells. It was therefore essential to study the release of cytokines from the latter cell type. On immunological stimulation with anti-immunoglobulin E (anti-IgE) or stem cell factor (SCF), purified human lung mast cells released, within 2-10 min, small amounts of tumour necrosis factor-alpha (10.5 +/- 2.9 pg/10(6) mast cells and 17.9 +/- 7.9 pg/10(6) mast cells, respectively) and interleukin-4 (5.3 +/- 2.5 pg/10(6) mast cells and 8.0 +/- 3.2 pg/10(6) mast cells, respectively). After longer periods of activation (30 min-4 h). the amounts of cytokines released from stimulated cells decreased to levels which were below those of the unstimulated cells. This possible degradation of cytokines by mast cells could not be prevented by the addition of protease inhibitors.

Antibodies, Anti-Idiotypic↗
PubMed1997

Characterization of prostate-specific antigen proteolytic activity on its major physiological substrate, the sperm motility inhibitor precursor/semenogelin I.

The protease prostate-specific antigen (PSA) is a marker widely used clinically for monitoring prostatic malignancies. Under normal conditions, this enzyme is mainly involved in the post ejaculation degradation of the major human seminal protein, the seminal plasma motility inhibitor precursor/semenogelin I (SPMIP/SgI), which is the predominant protein component of human semen coagulum. PSA primary structure and activity on synthetic substrates predict a chymotrypsin-like activity whose specificity remains to be established. The present study was aimed at characterizing the proteolytic processing of the SPMIP/SgI by PSA. Purified SPMIP/SgI was incubated with PSA in the presence or absence of protease inhibitors. General serine protease inhibitors, heavy metal cations (Zn2+ and Hg2+), and the heavy metal chelator 1,10-phenanthroline partially or totally inhibited the proteolytic activity of PSA toward SPMIP/SgI. Under identical conditions, other proteins, such as bovine serum albumin, ovalbumin, and casein, were very poor substrates for PSA. Hydrolysis products were separated by reverse-phase high-performance liquid chromatography, assayed for sperm motility inhibitory activity, and analyzed by immunoblotting and mass spectrometry. The region responsible for the sperm motility inhibitory activity and containing an SPMI antiserum epitope was localized to the N-terminal portion of the molecule between residues 85 and 136. On the other hand, a monoclonal antibody against a seminal vesicle-specific antigen (MHS-5) recognized fragments derived from the central part of the SPMIP/SgI (residues 198-223). PSA hydrolysis occurred almost exclusively at either leucine or tyrosine residues, demonstrating directly for the first time a restricted chymotrypsin-like activity on a physiological substrate. The results suggest that PSA is the main enzyme responsible for the processing of SPMIP/SgI in human semen and that this protease manifests unusual specificity with respect to hydrolyzable substrates and sites of hydrolysis.

Amino Acid Sequence↗
PubMed1997

Styrene toxicity: an ecotoxicological assessment.

Although other aromatic compounds (e.g., benzene, toluene, polycyclic aromatic hydrocarbons (PAH), etc.) have been thoroughly studied over the years, styrene has been given little attention probably due to its lower rate of industrial use. In addition, it is less toxic than benzene and PAH, proven carcinogens. However, it is classified as a mutagen and thus potentially carcinogenic. Its main use is in the production of the polymer polystyrene and in the production of plastics, rubber, resins, and insulators. Entry into the environment is mainly through industrial and municipal discharges. In this review, the toxicological effects of styrene on humans, animals, and plants are discussed. Its mode of entry and methods of monitoring its presence are examined. Although its effects on humans and aquatic life have been studied, the data on short- or long-term exposures to plants, birds, and land animals are insufficient to be conclusive. Since exposure to workers can result in memory loss, difficulties in concentration and learning, brain and liver damage, and cancer, development of accurate methods to monitor its exposure is essential. In addition, the review outlines the present state of styrene in the environment and suggests ways to deal with its presence. It might appear that the quantities are not sufficient to harm humans, but more data are necessary to evaluate its effect, especially on workers who are regularly exposed to it.

Animals↗