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Biomedical subjects

U Darsow

Publications and source records attributed to U Darsow.

At least 19 recordsLinked to original sources
PubMed2001

Central activation by histamine-induced itch: analogies to pain processing: a correlational analysis of O-15 H2O positron emission tomography studies.

The aim of this study was to identify the functional cerebral network involved in the central processing of itch and to detect analogies and differences to previously identified cerebral activation patterns triggered by painful noxious stimuli. Repeated positron emission tomography regional cerebral blood flow (rCBF) measurements using O15-labeled water were performed in six healthy right-handed male subjects (mean age 32 +/- 2 years). Each subject underwent 12 sequential rCBF measurements. In all subjects a standardized skin prick test was performed on the right forearm 2 min before each rCBF measurement. For activation, histamine was applied in nine tests in logarithmically increasing concentrations from 0.03 to 8%. Three tests were performed with isotonic saline solution serving as a control condition. Itch intensity and unpleasantness were registered with a visual analogue scale during each test. Subtraction analysis between activation and control conditions as well as correlation analysis with covariates were performed. Itch induced a significant activation in the predominantly contralateral somatosensory cortex and in the ipsilateral and contralateral motor areas (supplementary motor area (SMA), premotor cortex, primary motor cortex). Additional significant activations were found in the prefrontal cortex and the cingulate gyrus, but not in subcortical structures nor in the secondary somatosensory cortex. In correlation analyses, several cortical areas showed a graded increase in rCBF with the logarithm of the histamine concentration (bilateral sensorimotor areas and cingulate cortex; contralateral insula, superior temporal cortex and prefrontal cortex) and with itch unpleasantness (contralateral sensorimotor cortex, prefrontal cortex and posterior insula; ipsilateral SMA). Induction of itch results in the activation of a distributed cerebral network. Itch and pain seem to share common pathways (a medial and a lateral processing pathway and a strong projection to the motor system). In contrast to pain activation studies, no subcortical (i.e. thalamic) activations were detected and correlation analyses suggest differences in subjective processing of the two sensations.

Adult↗
PubMed2000

Subcutaneous oleomas induced by self-injection of sesame seed oil for muscle augmentation.

This case presentation describes a 48-year-old man who experienced subcutaneous nodules 9 months after self-injection of sesame seed oil into the pectoral area for muscle augmentation. This procedure was reported by our patient to be frequently performed in the body-building and fitness scene. Ultrasound imaging showed multiple, low reflecting round nodular areas of up to 1 cm diameter in both breasts. Excision of a representative nodule revealed a cyst filled with oily material, surrounded by granulomatous tissue. This case report demonstrates an unusual side effect of augmentation measures in body-builders.

Calcinosis↗
PubMed2000

Airborne and dietary allergens in atopic eczema: a comprehensive review of diagnostic tests.

Aeroallergens and food allergens are relevant eliciting factors of atopic eczema. This article focuses on the methods used for diagnosis in patients with suspected allergy to airborne or dietary allergens and who are suffering from atopic eczema. In addition to classical tests of IgE-mediated hypersensitivity (intracutaneous or in vitro testing), the role of provocation procedures is described. For aeroallergens, the atopy patch test yields the most specific results with regard to clinical history as compared with classical methods. For food allergens and pseudoallergic reactions to additives, this holds true for the double-blind, placebo-controlled food challenge. The methods and their limitations are discussed from a practical point of view.

Allergens↗
PubMed2000

Processing of histamine-induced itch in the human cerebral cortex: a correlation analysis with dermal reactions.

The subjective sensation of itch is a complex emotional experience depending on a variety of factors. In this study, the central nervous processing of pruritus was investigated in a human model. Activation of involved cerebral areas was correlated to scales of nociception and skin reactions. Six healthy male right-handed subjects participated in a standardized epidermal stimulus model with nine increasing doses of histamine dihydrochloride (0.03%-8%) on their right forearms. Controls consisted of three NaCl stimuli. Cerebral activation patterns were determined by H(2)(15)O positron emission tomography 120 s after stimulation. Dermal reactions to the stimulus (wheal, flare, temperature) were coregistered during the procedure. Itch sensation was determined by visual analog scale rating. Pain was not reported during the study; all volunteers had localized itch from 0.03% histamine on. Subtraction analysis versus control revealed significant activation of the left primary sensory cortex and motor-associated areas (mainly primary motor cortex, supplementary motor area, premotor cortex). Predominantly left-sided activations of frontal, orbitofrontal, and superior temporal cortex and anterior cingulate were also observed. Correlation analysis revealed coactivation of dermal reactions and cerebral response to itch in the following Brodmann areas with a Z score greater than 5: wheal, areas 5 (bilateral) and 19 (right); flare, areas 2-5 (left); temperature, area 10 (left) and left insula. Itch intensity ratings were mainly correlated with activation of the left sensory and motor areas. Functional covariates of the itch sensation in the central nervous system were identified. The intention to pruritofensive movements is probably mirrored by the activation of motor areas in the cortex. Other areas may be involved in emotional processing of sensations. Skin reactions wheal and flare also had significantly activated covariate areas in the central nervous system.J Invest Dermatol 115:1029-1033 2000

Adult↗
PubMed2000

Skin surface pH, stratum corneum hydration, trans-epidermal water loss and skin roughness related to atopic eczema and skin dryness in a population of primary school children.

Non-invasive investigations of skin morphology and function are standard tools to study the pathophysiology of several cutaneous disorders, yet they have not been used in population-based epidemiological studies. Here we examined skin surface pH, stratum corneum hydration, trans-epidermal water loss (TEWL) and skin roughness by profilometry in a study population comprising 377 primary school children (8-9 years old) as part of a multicentre survey on risk factors for allergic diseases in school children. Skin surface pH showed significant higher values (p=0.029) in the group with atopic eczema (n=45) compared with the group without atopic eczema; all other parameters did not differ significantly between children with and without atopic eczema. With increasing skin dryness there was a significant increase in pH values (p=0.004). Stratum corneum hydration showed a significant decrease with increasing dryness (p<0.001). Measurement of skin roughness also revealed a significant linear relationship with skin dryness (p=0.02). It is concluded that measurement of skin surface pH, corneometry and profilometry are useful non-invasive techniques to objectively assess skin dryness in epidemiological studies regarding atopic skin disease.

Body Water↗
PubMed1999

Evaluating the relevance of aeroallergen sensitization in atopic eczema with the atopy patch test: a randomized, double-blind multicenter study. Atopy Patch Test Study Group.

BACKGROUND: IgE-mediated sensitization of questionable clinical relevance is routinely demonstrated in patients with atopic eczema (AE) by skin prick test or radioallergosorbent test (RAST). We report the results of a randomized, double-blind multicenter study in patients with AE on the relevance and technical aspects of aeroallergen patch testing (atopy patch test, APT). METHODS: Two hundred fifty-three adult patients with AE in remission were tested in 7 study centers on clinically uninvolved, unabraded back skin with 3000 to 10,000 PNU/g of Dermatophagoides pteronyssinus, cat dander, grass, birch, and mugwort pollen allergen extracts in petrolatum. After skin prick and RAST and a detailed history on aeroallergen-induced eczema flares was obtained, reading was done at 48 to 72 hours. RESULTS: Previous eczema flares after contact with specific allergens were reported by 10% (mugwort pollen) to 52% (D pteronyssinus) of patients. The percentage of clear-cut positive APT reactions ranged from 44% with D pteronyssinus to 5% with mugwort. Positive skin prick (36% to 65%) and RAST (49% to 75%) results were more frequent. APT results showed significant concordances with history, skin prick, and RAST for D pteronyssinus, cat dander, and grass pollen (P < .001). Optimal test concentrations were 5000 (grass pollen) and 7000 PNU/g (D pteronyssinus, cat dander). The APT had a higher specificity (69% to 92% depending on allergen) with regard to clinical relevance of an allergen compared with skin prick test (44% to 53%) and RAST (42% to 64%). CONCLUSION: Aeroallergens are able to elicit eczematous skin reactions after epidermal application. The relevance of aeroallergens for AE flares may be evaluated by APT.

Adolescent↗
PubMed1999

Atopy patch test reactions are associated with T lymphocyte-mediated allergen-specific immune responses in atopic dermatitis.

BACKGROUND: Positive test reactions to epicutaneous application of aeroallergens served as a model of 'early' eczema in atopic dermatitis (AD) in a number of dermato-immunological studies. However, no quantitative evaluation has been performed so far comparing specific T-cell activation parameters in the peripheral blood of AD patients with positive or negative atopy patch tests (APT). OBJECTIVE: The purpose of this study was to investigate specific immunological parameters in patients with atopic dermatitis showing positive or negative atopy patch tests reactions. METHODS: APT results (n = 96) were compared with allergen-specific IgE, specific lymphocyte proliferation, and the expression of 'activation' markers on peripheral blood T-cells upon in vitro stimulation with house dust mite, cat or grass pollen allergens. RESULTS: Only a subpopulation (48%) of patients sensitized to aeroallergens (i.e. specific IgE > 0.7 kU/L) developed APT-reactions to the corresponding allergen. APT reactions were, however, significantly associated with allergen specific lymphocyte proliferation (p < 0.0001), and a higher number of CD54+ or CD30+ T-cells (p < 0.05) upon in vitro stimulation. CONCLUSION: The association of delayed skin reactions with allergen specific T-cell parameters in the blood points to an immunologically mediated mechanism leading to positive reactions in the APT.

Allergens↗
PubMed1997

[Allergy and atopic eczema: on the value of the "atopy patch test"].

The role of allergic reactions in eliciting and maintaining atopic eczema (AE) is still controversial. In a subgroup of patients with atopic eczema, exacerbations of itching and eczematous skin lesions have been described after contract with aeroallergens. To investigate this observation, an epicutaneous patch test with IgE-inducing allergens (atopy patch test, APT) has been proposed, which results in eczematous skin reactions in 30-70% of AE patients. Usage of allergen concentrations exceeding 5000 PNU/g in petrolatum allows testing on clinically uninvolved skin without potentially irritating epidermal tape stripping. The clinical relevance of positive APT reactions is suggested by comparison of APT with skin prick test, specific IgE, patient's history and eczema pattern. Patients with an eczema pattern with preferred localization of skin lesions in air-exposed areas, a predictive history and raised specific IgE (depending on allergen) were shown to have the highest rate of positive APT. Future controlled studies with allergen avoidance and reexposition may focus on this patient group.

Allergens↗
PubMed1997

[The Eppendorf Pruritus Questionnaire].

In dermatological practice, itch is the leading symptom of many skin diseases with a variety of psychophysiological aspects. However, a complete inventory for the qualitative evaluation of these central nervous factors is missing, whereas in pain research, the McGill Pain Questionnaire is well established for this purpose. Thus, therapeutic effects of antipruritic agents are only incompletely described by visual analog scales or parameters of skin physiology. Here, a questionnaire modified in analogy to the McGill pain questionnaire is presented, developed in cooperation between dermatologists and neurophysiologists.

Diagnosis, Differential↗
PubMed1997

Gramineae pollen as trigger factors of atopic eczema: evaluation of diagnostic measures using the atopy patch test.

After contact with grass pollen, seasonal exacerbations of eczematous skin lesions have been described in a subgroup of patients with atopic eczema (AE). Epicutaneous patch testing with aeroallergens (atopy patch test. APT) has been used to investigate these patients. We performed comparative APT in 79 patients with AE and 20 control subjects (14 non-atopic volunteers and six patients with grass pollen allergic rhinoconjunctivitis). Subjects were tested with grass pollen allergen extract in petrolatum and with unprocessed native dry pollen of Dactylis glomerata. Results after 48 h were compared with the patient's history, corresponding skin prick test and specific IgE. Fifteen of the 79 AE patients showed clear-cut eczematous reactions to unprocessed D. glomerata pollen; 14 of these had an elevated serum IgE to D. glomerata and 13 had a positive skin prick test. Twenty patients had a positive APT reaction to grass pollen allergen extract, including 12 of the D. glomerata reactive subjects (P < 0.001). Positive patch test reactions to D. glomerata were seen in 66.7% of cases with and 10.5% of patients without a predictive history of exacerbations during the pollen season. For the standardized extract, these percentages were 75% vs. 16.4% (P < 0.001). No side-effects were observed. Control subjects showed no positive reactions. We conclude that grass pollen preparations may be used to investigate trigger factors for eczematous skin lesions in a subgroup of patients with AE.

Adolescent↗
PubMed1997

Skin testing of the pruritogenic activity of histamine and cytokines (interleukin-2 and tumour necrosis factor-alpha) at the dermal-epidermal junction.

Cytokines have been proposed as histamine-independent itch mediators. To investigate this hypothesis, single doses of interleukin-2 (IL-2, 10 MU/mL) and tumour necrosis factor alpha (TNF-alpha, 10 micrograms/mL) were delivered to the epidermis of 10 healthy volunteers with a controlled skin-prick model; 1% histamine and solvent controls were included in a double-blind, randomized crossover design. Itch ratings (computerized visual analogue scale) were obtained every 20 s for 15 min and cutaneous reactions (weal, flare and temperature) were measured. Reactions were also recorded after 2, 24 and 48 h. The mean itch ratings were: histamine 35.5, IL-2 3.3 (both P < 0.01 compared with control), TNF-alpha 1.6 and solvent control 1.75 (not significant). Weal and flare occurred only with histamine. In two volunteers, an inflammatory papule with transient pruritus developed 12-18 h after applying IL-2. In conclusion, IL-2 showed a rapid, low pruritogenic effect, which may be followed by an inflammatory response. TNF-alpha induced no itching in this setting. Skin-prick testing with appropriate doses of potential pruritogens provides a safe and sensitive model for further chemoreceptor studies.

Adult↗
PubMed1996

Correlations between histamine-induced wheal, flare and itch.

Correlations between the skin reactions wheal and flare and the subjectively reported degree of itch were investigated in response to 1% histamine, intradermally applied by standardized skin prick and by iontophoresis. Experiments were performed with 15 male volunteers using a threefold repeated measures design (skin prick, and iontophoresis with 0.13 mA for 10 s and with 2.0 mA for 10 s). Skin reactions (perpendicular diameters) were determined at the time of their maximum (10 min). Itch was rated on a computerized visual analogue scale which was anchored upon the individual scratch threshold. Most effective in producing itch was the skin prick which caused strong sensations markedly above the scratch threshold during the entire period of measurement (30 min), whereas iontophoresis induced only transient itch sensations. On the other hand, the largest wheals were generated by iontophoresis of both intensities (mean 10 or 14 mm vs 6 mm with skin prick). The higher current induced higher itch, wheal and flare responses, but after eliminating this effect of stimulus intensity, no correlations were found. In contrast, skin prick-induced flare reactions varied with the degree of itch above the scratch threshold (r = 0.56; P < 0.01). Repeated measurements showed a higher stability for the itch reaction with skin prick compared with iontophoresis. It is hypothesized that in iontophoresis the brief (10-s) histamine bolus passed the most superficial pruritoceptive C fibres too quickly to induce long-lasting itch sensations, whereas the skin prick caused a deposit at the dermal-epidermal junction releasing histamine during the entire time of measurement. Consequently, both the C fibre-mediated itch and the axon reflex flare were more pronounced with the skin prick, and the wheal resulting from a permeability increase in the postcapillary venule walls was an independent phenomenon.

Adult↗
PubMed1996

Pruritus circumscriptus sine materia: a sequel of postzosteric neuralgia. Evaluation by quantitative psychophysical examination and laser-evoked potentials.

A case of circumscribed pruritus existing since 1 year on clinically uninvolved skin is reported, in which careful history revealed a 5-year previous episode of herpes zoster in the same dermatome. Impairment of cutaneous sensitivity was evaluated by use of a quantitative psychophysical examination and laser-evoked cortical potentials (LEP).

Aged↗
PubMed1996

The atopy patch test: an increased rate of reactivity in patients who have an air-exposed pattern of atopic eczema.

In a subgroup of patients with atopic eczema (AE), eczematous skin lesions can be induced by epicutaneous testing with aeroallergens (the atopy patch test: APT). An increased frequency of positive APT has been found in AE patients showing a predictive lesional pattern affecting air-exposed skin areas. This study investigates the dose-response of the APT in two different patient groups with AE. Petrolatum preparations of house dust mite, cat dander and grass pollen allergens in four concentrations (500-10,000 protein nitrogen units) were tested epicutaneously in 57 patients with AE, who were prospectively divided in two groups according to whether their AE pattern was with (group I) or without (group II) a predictive distribution. Sixty-nine per cent of patients in group I, and 39% in group II, had positive APT reactions (P = 0.02). The reactions in group I were elicitable with lower allergen concentrations (P = 0.03). A clinically recognizable subgroup of patients with AE showed increased cutaneous sensitivity to aeroallergens.

Adolescent↗
PubMed1995

Effects of menthol and cold on histamine-induced itch and skin reactions in man.

The effects of cooling and topical application of menthol on histamine-induced itch, wheal and flare reactions of the left lower arm were investigated in a threefold cross-over design with 15 healthy male volunteers. Lowering skin temperature by cooling from 32.8 +/- 0.3 degrees C to 29.7 +/- 0.5 degrees C reduced itch intensity from 260 +/- 47 units to 55 +/- 12 units (visual analogue scale) and flare diameters from 39.0 +/- 2.0 mm to 30.2 +/- 1.8 mm; wheal reactions were not affected. A similar reduction in itch was found under menthol (42 +/- 14 units) although skin temperature was not decreased. These findings suggest a central inhibitory effect of cold sensitive A-delta fibre activation on itch.

Adult↗
PubMed1995

Atopy patch test with different vehicles and allergen concentrations: an approach to standardization.

BACKGROUND: In some patients with atopic eczema, eczematous skin lesions can be induced by patch testing with aeroallergens. METHODS: To establish a standardized system for the atopy patch test (APT), 36 patients with atopic eczema, four patients with rhinoconjunctivitis and 10 healthy control subjects were epicutaneously tested with allergen extracts from house dust mite, cat dander, and grass pollen. APTs were performed on nonabraded, uninvolved skin with 1000 and 10,000 protein nitrogen units (PNU)/gm allergen in petrolatum or hydrogel. Reactions were evaluated after 48 and 72 hours and compared with skin prick and specific serum IgE (CAP-RAST; Pharmacia, Uppsala, Sweden). RESULTS: After 48 hours, 57 clear-cut positive reactions with eczematous, often follicle-bound, appearance were diagnosed from a total of 432 test sites. Seventy-two percent of these positive reactions in patients with atopic eczema developed with 10,000 PNU/gm and 28% with 1000 PNU/gm. Sixty-seven percent of reactions were elicited with allergens in petrolatum versus 33% when hydrogel was used as vehicle. Allergen-specific concordances of APT (10,000 PNU/gm, petrolatum) ranged from 0.39 to 0.53 (prick test) and 0.42 to 0.69 (CAP-RAST). In healthy control subjects and patients with rhinoconjunctivitis without atopic eczema, no clear-cut positive APT reaction was seen. CONCLUSIONS: Petrolatum as vehicle and an allergen concentration higher than 1000 PNU/gm may lead to improved APT results on unchanged skin. In the future, the clinical relevance of an IgE-mediated sensitization for eczematous skin lesions may be evaluated by the APT.

Adolescent↗