Search PubMed⌕ Search

Biomedical subjects

A Boman

Publications and source records attributed to A Boman.

At least 19 recordsLinked to original sources
PubMed2005

Study of innervation, sensory neuropeptides, and serotonin in murine contact allergic skin.

Density of nerve fibers, axonal growth, calcitonin gene-related peptide (CGRP), and substance P, and serotonin immunoreactivity as well as concentration were all determined in a murine model of contact allergy. Female Balb/c mice were sensitized on the back with oxazolone and 6 days later challenged with the same antigen on the dorsal surface of the ears, while control mice received the vehicle only. Then, 24 hr postchallenge, one ear was processed for immunohistochemical staining, while the other was frozen and processed for gas chromatography-mass spectrometry or radioimmunoassay (RIA). Protein gene product 9.5 (PGP 9.5) positive nerve fibers showed a tendency to increase in inflamed ears versus control ears in epidermis as well as the dermis. Growth-associated protein-43 (GAP-43) positive fibers in the epidermis were increased (p < .01) in inflamed ears, compared with control ears, as was the case for the dermal fibers, indicating increased axonal growth. Total (epidermis and dermis) numbers of CGRP and substance P positive nerve fibers tended to increase in the inflamed skin in contrast to control skin. In contrast, RIA demonstrated a lower (p < .05) concentration of CGRP in the inflamed ears compared with controls and a tendency for substance P to decrease in concentration in eczematous ears versus controls. There was no difference in serotonin concentration, or in the number of serotonin positive mast cells, between the inflamed and control skin, whereas semiquantification of serotonin positive platelets showed an increase in the inflamed (+/+) compared with control ears (+). Our results indicate that 24 hr after being challenged with the antigen, at the peak of murine skin inflammation, axonal growth, sensory neuropeptides, as well as serotonin may be involved.

Animals↗
PubMed2003

Increased airway responsiveness of a common fragrance component, 3-carene, after skin sensitisation--a study in isolated guinea pig lungs.

Lungs from skin-sensitised and non-sensitised guinea pigs were exposed via the airways to 3-carene (1900 mg/m3) and perfused with buffer containing either autologous plasma or lymphocytes. The experiments were performed in order to investigate the importance of blood components for the increased lung responsiveness seen in skin-sensitised animals. A reduction in lung function was noted in all lungs during 3-carene exposure. There was no difference in the 3-carene response between lungs from skin-sensitised animals versus lungs from non-sensitised animals when the perfusion buffer contained lymphocytes. However, when plasma diluted with buffer was used as perfusion medium, there was a significant enhancement in the response in lungs from sensitised versus lungs from non-sensitised animals. This implies that skin sensitisation increases lung responses to inhaled 3-carene and those components in plasma, and not the lymphocyte fraction, contributes to the observed increased lung responsiveness.

Animals↗
PubMed2003

Ascaris nematodes from pig and human make three antibacterial peptides: isolation of cecropin P1 and two ASABF peptides.

Organisms co-habiting with bacteria have developed efficient bactericidal agents to control their microbe-rich environment. The Ascaris nematode lives in its final development stages in the gut of its host and is believed to feed on bacteria. Ascaris suum survive in pig intestine while A. lumbricoides is the principal species in humans. Here we show that A. suum and A. lumbricoides both produce linear (cecropin P1) and cysteine-rich (ASABF) peptides with activity against either gram-negative or gram-positive bacteria, respectively. Thus nematodes rely in part on a peptide-based antibacterial system for digestion of bacteria, which may also confer protection against infection. Cecropin P1 was previously isolated from pig intestine but we can now conclude that was due to contaminating nematodes.

Amino Acid Sequence↗
PubMed2001

[Task and task time should dictate the choice of gloves in health care services].

Worldwide consumption of medical gloves increased during the 1980's due to the recognized risk of cross infections in medical and dental care. In Stockholm County Council around 1 million pairs of surgical gloves and 18 millions pairs of examination gloves are purchased per year. In the following paper different glove materials and types are presented and also regulations on use and purchase. The protective capacity of gloves and contact hypersensitivity reactions are also discussed and advice is provided on glove usage.

Dermatitis, Allergic Contact↗
PubMed2000

Germ-free and colonized mice generate the same products from enteric prodefensins.

The use of germ-free mice offers the possibility to study antibacterial components in a gut uncolonized by bacteria. We have developed a method to extract and high pressure liquid chromatography-fractionate the antibacterial factors present in the small intestine of a single mouse. By mass spectrometry and sequence analyses of fractions exhibiting antimicrobial activity, we identified and characterized the defensin region in germ-free mice as well as in colonized mice. Defensins made up around 15% of the total antibacterial activity both in germ-free and colonized mice. The intestine of germ-free mice exhibited the same set of mature enteric defensins (defensins 1, 2, 3, 4, and 6) as mice colonized by a normal microflora. Mature defensins are generated through processing of larger precursors by enzymatic removal of a signal peptide and a propiece. We found that all prodefensins were cleaved at a Ser/Ala-Leu bond, giving 34-residue propiece peptides and only trace amounts of the predicted 39-residue peptide. This first step must be followed by the removal of a residual peptide to render the mature defensins, indicating that the processing is more complex than previously anticipated. The same propieces were found in both germ-free and colonized mice, suggesting that the same processing operates independent of bacterial presence in the intestine.

Amino Acid Sequence↗
PubMed2000

Increased airway responsiveness after skin sensitisation to 3-carene, studied in isolated guinea pig lungs.

Inhalation of 3-carene has been shown to induce bronchoconstriction in concentrations not far from the threshold limit value. In this study, one group of guinea-pigs were sensitised by dermal exposure to 3-carene according to the modified Cumulative Contact Enhancement Test protocol and another group of animals was used as controls. Lungs from the skin-sensitised and control guinea-pigs were perfused with diluted autologous blood (13 ml blood/87 ml buffer) and exposed to 3-carene at an air concentration of 3000 mg/m(3). In both groups there was a reduction in compliance and conductance but this reduction was significantly (P<0.05) more pronounced (2.5-3 times) in lungs obtained from sensitised animals than from control animals. In a previous study with similar design, but with plain buffer instead of diluted autologous blood as perfusate, we found no statistically significant difference in lung bronchoconstriction. Thus, it is concluded that skin sensitisation can increase lung reactivity to 3-carene and that important mediators of this effect seem to be present in the blood.

Administration, Inhalation↗
PubMed2000

Sensitizing potential of chlorothalonil in the guinea pig and the mouse.

The fungicide chlorothalonil is used extensively under several tradenames for the protection of various horticultural and fruit crops and bananas against fungal infections. It is also used as fungicide in wood preservation and as a preservative in paints. Clinical experience has shown chlorothalonil to be a contact allergen and several cases of allergic contact dermatitis attributed to chlorothalonil have been described. 2 previous guinea pig maximization test studies have shown the sensitizing potential of chlorothalonil to be high. The sensitizing property of chlorothalonil was studied by us with the predictive test methods the local lymph node assay and the cumulative contact enhancement test. In the local lymph node assay, chlorothalonil induced a dose-dependent increase in proliferation with a maximal stimulation index of 19.2 and 27.2. In the cumulative contact enhancement test, a statistically significant dose-dependent high sensitization rate was seen with a maximal sensitization rate of 100%. In conclusion, it is evident that chlorothalonil is an extremely potent contact allergen, inducing sensitization using only topical exposure on intact skin.

Animals↗
PubMed2000

Influence of evaporation and solvent mixtures on the absorption of toluene and n-butanol in human skin in vitro.

The influence of forced ventilation on the percutaneous absorption of butanol and toluene was studied in vitro. Human skin was exposed to the neat solvents and the solvents in binary mixtures with each other and in ternary mixtures with chloroform:methanol. The exposure was either unventilated or ventilated with various flow rates. At the ventilated exposure the skin absorption of all solvents and solvent mixtures was markedly reduced compared to unventilated exposure. Exposure with solvent mixtures increased the amounts of solvent absorbed as well as absorption rates. The absorption of the butanol component was most influenced. Increase in absorption was 11 to 9 times depending on whether toluene or chloroform/methanol was cosolvent. There was also an interindividual variation of absorption rate, varying with a factor of 3.5 for toluene and 4.3 for n-butanol within the 3 skin donors used. Skin absorption of volatile organic solvents at continuous ventilated conditions is related to their volatility and to the ventilation rate.A sufficient workplace ventilation is an important occupational hygienic measure not only to reduce exposure via respiration but to reduce absorption via the skin of volatile compounds as well.

1-Butanol↗
PubMed1999

Dose-response studies of contact allergens using 3 guinea pigs models.

A multi-dose-response induction protocol for the guinea pig maximization test (GPMT), including a statistical computer program, has earlier been developed to improve the power of predictive tests for identification of contact allergens. This dose-response protocol, with 2 modifications (i.e., increased number of animals in each group and increased number of challenge concentrations) was evaluated in the GPMT, the cumulative contact enhancement test (CCET) and the Freund's complete adjuvant test (FCAT), using potassium dichromate and hydroxycitronellal as model contact allergens. Application of the dose-response protocol on the CCET and the FCAT resulted in either monotone or non-monotone curves with significant dose-response. However, application of the dose-response protocol on the GPMT gave curves with no significant dose-response. The protocol makes it possible to obtain an EC50 value, thus improving the possibility of ranking contact allergens, which is of substantial use for risk assessments. The dose-response protocol could benefit from a few adjustments: a wider span in the induction doses; change to simultaneous increase in intradermal and topical induction doses to obtain a proper dose-response for the GPMT; the addition of further challenge concentrations. In addition the computer program should allow calculation of threshold concentration for sensitization and EC50 value for a non-monotone curve.

Allergens↗
PubMed1999

Sensitizing potential in mice, guinea pig and man of the preservative Euxyl K 400 and its ingredient methyldibromo glutaronitrile.

The allergenicity of the preservative Euxyl K 400 and its principal allergen methyldibromo glutaronitrile (MDBGN) (1,2-dibromo-2,4-dicyanobutane) was investigated using 3 animal models; in mice, the local lymph node assay (LLNA) and in guinea pigs, the guinea pig maximization test (GPMT) and the cumulative contact enhancement test (CCET) with a dose-response protocol included. Previous attempts to define the sensitization capacity of these chemicals have given conflicting results. For comparison, the frequency and causes of positive patch test reactions to Euxyl K 400 and MDBGN were studied in patients referred to an occupational dermatology clinic. This investigation showed that Euxyl K 400 and MDBGN can give rise to contact allergy in man and that the relevant cases found mainly had similar exposure as non-occupational cases. A contact allergenic potential could be detected for MDBGN in 2 animal models, i.e., the CCET and the LLNA, and also for Euxyl K 400 in the LLNA. However, statistical analysis of the results from the GPMT with MDBGN failed to detect the sensitizing potential of this particular allergen. The results indicate that to be able to detect the allergenic potential of Euxyl K 400 and MDBGN, a predictive test method with multiple topical applications at induction is required. It is therefore important that an investigator is aware of the possibility of using various predictive test models for investigation of potential contact allergens.

Allergens↗
PubMed1999

Demonstration of estrogen receptor-beta immunoreactivity in human growth plate cartilage.

Estrogens affect longitudinal bone growth through their action on endochondral bone formation. Two estrogen receptors are known, the classical estrogen receptor-alpha (ER alpha), newly demonstrated in human growth plate cartilage, and a recently cloned estrogen receptor-beta (ER beta). The present study aimed to localize a possible expression of ER beta protein in human growth plates. Tissue samples were obtained from tibial and femoral growth plates in four female pubertal patients undergoing epiphyseal surgery. Immunohistochemistry, using two different ER beta-specific antibodies, demonstrated positive staining for ER beta in hypertrophic epiphyseal chondrocytes from all patients. No staining was noted in resting or proliferative chondrocytes. These data suggest that in addition to ER alpha, human epiphyseal chondrocytes also express ER beta. The physiological role of ER beta in the regulation of longitudinal bone growth in humans remains to be elucidated.

Adolescent↗
PubMed1998

Does airway responsiveness increase after skin sensitisation to 3-carene: a study in isolated guinea pig lungs.

Guinea pigs were sensitised by dermal exposure to 3-carene according to the modified cumulative contact enhancement test (CCET) protocol. Lungs from sensitised and non-sensitised animals were then perfused with buffer and exposed for a period of 10 min to two different air concentrations of 3-carene, 600 and 3000 mg/m3. 3-Carene caused a statistically significant bronchoconstriction even at the relatively low concentration of 600 mg/m3 and the constriction was dose dependent. 600 mg/m3 of 3-carene caused a reduction of 19% in conductance capacity and 16% in compliance capacity. 3000 mg/m3 of 3-carene decreased lung compliance and conductance by 43 and 31%, respectively. The lungs from sensitised animals tended to show a greater response than lungs obtained from control animals. The lower concentration of 3-carene is close to and may even be below, occupational limit values in Sweden, Germany and USA.

Allergens↗
PubMed1998

Experimental infections of Rana esculenta with Aeromonas hydrophila: a molecular mechanism for the control of the normal flora.

Frogs can be useful models for studying the mechanisms that may regulate their natural microbial flora. Their skin glands produce a secretion containing 20-30 different peptides, some antimicrobial some neurotrophic. As they often live in soil or silt that is rich in microbes, they can be expected to be able to prevent or eliminate infections in very short periods of time. The bacterium Aeromonas hydrophila is widely distributed in nature and is considered as part of the natural flora of frogs and many animals, including humans. From an alternative frog strain of A. hydrophila, Bo-3, we isolated a spontaneous and stable mutant (Bo-3N), resistant to nalidixic acid, here used to follow the host-microbe interactions in experimental infection of mouth and skin of Rana esculenta. The skin peptides had been previously isolated, sequenced and cloned. We showed that skin treatment with a glucocorticoid (GC) cream blocked de novo synthesis of these peptides and, simultaneously, prepropeptide mRNAs disappeared while IkappaBalpha was up-regulated. Experimental mouth infections with 20 million cells of A. hydrophila Bo-3N showed that a normal wild frog can eliminate the bacteria from the mouth within 15 min, while a frog pretreated with GC cream for 1 h could not reduce Bo-3N below 3500 colony-forming units (CFU)/5 microl 'saliva'. An in vitro comparison showed that frog blood or serum allowed bacteria to grow, while the skin secretion killed the bacteria within 10 min. Using different enzyme-linked immunosorbent assays (ELISAs) with rabbit anti-Bo-3 serum as a positive control, we were able to rule out immunoglobulin G (IgG) binding to A. hydrophila. An assay for immunoglobulin M (IgM) (or some other serum component) in frog serum showed binding to A. hydrophila only corresponding to a few per cent of the positive control. For skin infections we bathed the frogs for 10 min in an overnight culture of Bo-3N diluted to about 10(7) CFU/ml. Electrical stimulation after the bath showed, for the total secretion, a two to fourfold increase in the antibacterial activity, while a pretreatment with GC cream reduced the activity to about one-third of that of the non-bathed control frog. HPLC analysis of the peptide pattern confirmed these findings. The survival value of antimicrobial peptides have earlier been demonstrated in vivo and in vitro only in Drosophila. The present experiments are the first combined in vivo and in vitro demonstrations of the function of peptide antibiotics in a vertebrate. One such function is involved in the control of the natural flora.

Aeromonas hydrophila↗
PubMed1998

Murine local lymph node assay for predictive testing of allergenicity: two irritants caused significant proliferation.

The murine local lymph node assay is a method for predictive testing of contact allergenicity, but its ability to discriminate between allergens and irritants has been questioned. To explain some of the conflicting results with irritants, the proliferation induced by methyl salicylate and nonanoic acid, both considered to be non-sensitisers, was further investigated. Both substances showed a dose--response relationship and clearly positive results when tested at higher concentrations (> or = 50%) and would thus be classified as potential sensitisers according to the present criteria for a positive assay result. In the case of methyl salicylate, the use of either dimethyl formamide or methyl ethyl ketone as vehicle did not significantly influence the results. The negative results obtained for methyl salicylate in some earlier reports were probably due to testing at too low concentrations. The proliferation induced by irritants such as methyl salicylate and nonanoic acid and inter alia sodium dodecyl sulfate, Triton X-100, oxalic acid, chloroform/methanol (2:1) must be better recognized and elucidated before the assay can be generally accepted as a predictive test method.

Allergens↗
PubMed1997

Effect of glucocorticoids on the synthesis of antimicrobial peptides in amphibian skin.

Gene-encoded peptide antibiotics are widespread in insects, plants and vertebrates and confer protection against bacterial and fungal infections. NF-kappaB is an important transcription factor for many immunity-related mammalian proteins and also for insect immune genes. The activity of NF-kappaB is regulated by the interaction with an inhibitor, I kappaB. It was recently demonstrated that glucocorticoids induce the synthesis of I kappaB in human cell lines. So far, all genes for peptide antibiotics have promoter motifs with NF-kappaB binding sites, but its actual function in peptide regulation has been studied only in insects. Here we show that glucocorticoid treatment of the frog Rana esculenta inhibits the transcription of all genes encoding antibacterial peptides by inducing the synthesis of I kappaB alpha. These results suggest that also in vertebrates peptide-mediated innate immunity is controlled by NF-kappaB-regulated transcription.

Amphibian Proteins↗
PubMed1997

Skin absorption of the industrial catalyst dimethylethylamine in vitro in guinea pig and human skin, and of gaseous dimethylethylamine in human volunteers.

OBJECTIVES: The aims of the study were three-fold: to assess the skin uptake of the industrial catalyst dimethylethylamine (DMEA) (a) in vitro from water solutions by fresh guinea-pig and human skin specimens, (b) in gaseous form in vivo in human volunteers, and (c) to estimate the relevance of the uptake as an occupational hazard. METHODS: Specimens from the in vitro and in vivo experiments were analysed by gas chromatography using a nitrogen-sensitive detector. DESIGN: DMEA, diluted with water or isotonic saline solution was applied to fresh human or guinea-pig skin, mounted in Teflon flow-through cells with a perfusion fluid flow rate of 1.5 ml/h, samples being collected at 2-h intervals for 48 h. Three healthy male volunteers each had their right forearm exposed (in a Plexiglass chamber) for 4 h to DMEA at each of three different levels (250, 500 and 1000 mg/m3 air). Urine was collected up to 24 h after the start of each experiment. RESULTS: DMEA penetrated both guinea-pig and human skin. The median steady-state flux and permeability coefficient (Kp) values, were 0.009 mg/cm2 x h and 0.001 cm/h, respectively, for guinea-pig skin, and 0.017 mg/cm2 x h and 0.003 cm/h, respectively, for human skin. The median uptake in the three volunteers at the different DMEA exposure levels (250, 500 or 1000 mg/m3) was 44, 64 and 88 micrograms, respectively. The median Kp for all experiments was 0.037 cm/h. CONCLUSION: Uptake of DMEA through the skin is of far less importance than simultaneous uptake via the airways. Thus, the amount of DMEA excreted in urine is a variable of limited use for the purposes of biological monitoring. Although a wide range of Kp values was obtained in the in vitro experiments, both for guinea-pig and human skin, there was no marked difference in median Kp values between the two types of skin. The Kp values were lower than those obtained for human forearm skin in vivo. However, future studies of other tertiary aliphatic amines may show the in vitro method to yield values predictive of those obtained in in vivo studies.

Adult↗
PubMed1996

Biochemical and antibacterial analysis of human wound and blister fluid.

Fluid from a post-operative wound, six leg ulcers and a large blister were collected and analysed by biochemical, microbiological and immunological techniques. The results were compared with those from sera. All samples were lyophilized and extracted twice with 60% aqueous acetonitrile containing 1% trifluoroacetic acid. The pooled supernatants were lyophilized, redissolved, and the fluid extracts were characterized by six techniques (the blister exudate only with three): reverse-phase HPLC, Edman degradation, mass spectrometry, Western blot analysis, inhibition zone assay on plates with Bacillus megaterium (anti-Bm activity) and zone clearing on plates with cell walls from Micrococcus luteus (a lysozyme assay). The material corresponding to HPLC peaks of the wound fluid extract was identified as: histone H2B fragments 1-11,1-15 and 1-16, intact thymosin beta-4, defensins HNP1, 2 and 3, lysozyme and the peptide antibiotic FALL-39 and its precursor(s). The HPLC-separated blister fluid was extremely rich in anti-Bm activity (mainly defensins) and lysozyme. It may also contain factors not identified before. The plate assays scored 50-fold differences in anti-Bm activities and more than 10-fold differences in lysozyme, factors which together with thymosin could be active in wound healing. It is concluded that analysis of wound fluid yields peptide and activity patterns with novel fragments of important peptides, and quantitative differences, that can be useful to understand molecular mechanisms of wound healing further.

Adult↗