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Biomedical subjects

Johannes Wohlrab

Publications and source records attributed to Johannes Wohlrab.

15 recordsLinked to original sources
PubMed2005

Profiling of human stratum corneum ceramides by means of normal phase LC/APCI-MS.

The ceramides of the stratum corneum are critical to maintaining the epidermal barrier function of the skin. A number of skin diseases and disorders are known to be related to impairments of the ceramide pattern. Therefore, obtaining mass spectrometric profiles of the nine ceramide classes known to exist aids our understanding of the underlying molecular mechanisms, which should eventually lead to new diagnostic opportunities: for example, the mass spectrometric profiles of patients suffering from serious skin diseases such as atopic dermatitis and psoriasis can be compared to those of healthy controls. Previous work on mass spectrometric analysis of ceramides relied mostly on GC/MS after hydrolysis and derivatization. The introduction of ESI-MS and LC/ESI-MS has provided new options for directly analyzing intact ceramides. However, some of the ceramide classes are not accessible to ESI-MS. However, as shown in this work, these limitations of GC/MS and ESI-MS can be overcome using a new approach based on normal phase LC interfaced with APCI-MS. Separation and online detection of the stratum corneum ceramide classes became possible in one run. Ceramide species with C26 and/or C28 fatty acid chains were the most abundant ones in Cer [NP], Cer [NH], Cer [AP], and Cer [AH]. The main component of Cer [AS] was C16. The omega-esterified ceramide classes Cer [EOS], Cer [EOP] and Cer [EOH] contained mostly species with fatty acids >C30. This was also the case for Cer [NS], suggesting an analogy to the omega-esterified ceramides. In addition, evidence for a new ceramide class Cer [NdS] was found.

Ceramides↗
PubMed2005

Ceramide profiles of the uninvolved skin in atopic dermatitis and psoriasis are comparable to those of healthy skin.

Ceramides are sphingolipids consisting of sphingoidbases, which are amide-linked to fatty acids. In the stratum corneum, they represent the major constituent of the free extractable intercellular lipids and play a significant role in maintaining and structuring the water permeability barrier of the skin. Using thin layer chromatography, which represents the method of the first choice in analyzing the stratum corneum ceramides, at least seven classes can be distinguished. Each ceramide class contains various species, which have the same head group and different chain lengths. As in many other skin disorders, atopic dermatitis and psoriasis show derangements in content and profile of the ceramides. Such derangements were reported for both the lesional involved as well as for the normal-appearing uninvolved skin. In this study, we focused on investigating the stratum corneum ceramides of the uninvolved skin in atopic dermatitis and psoriasis patients compared to healthy skin. The aim of the investigations was to explore possible significant and specific differences which can be accomplished for purposes of early diagnostics. The skin lipids were collected by means of an in vivo topical extraction procedure using an extraction mixture consisting of n-hexane and ethanol, (2:1). An automated multiple development-high performance thin layer chromatography (AMD-HPTLC) method with photodensitometric detection were applied to separate the ceramides and to estimate their contents. For studying their molecular profile within each ceramide class, a new method of normal phase HPLC with atmospheric pressure chemical ionization mass spectrometry were used. The results obtained by AMD-HPTLC exposed no significant alterations regarding the relative composition of the major stratum corneum lipids and primarily the ceramides. In addition, the mass spectrometric profiles within each ceramide class were similar in the patients and the healthy control subjects. In conclusion, this study revealed that the normal-appearing uninvolved skin of atopic dermatitis and psoriasis patients does not prove significant or specific deficiencies with respect to the free extractable major stratum corneum lipids and mainly the ceramides, when compared to healthy skin. Thus, they cannot be used for diagnostic purposes. Furthermore, our data are not consistent with the concept that impairments in the ceramide composition represent an obligate etiologic factor for both diseases.

Adult↗
PubMed2005

Persistent erythema and edema of the midthird and upper aspect of the face (morbus morbihan): evidence of hidden immunologic contact urticaria and impaired lymphatic drainage.

BACKGROUND: A persistent erythema and edema of the midthird and upper aspect of the face, which bears some resemblance to Melkersson-Rosenthal syndrome and rosaceous lymphedema, has been characterized as morbus morbihan (MM) by French dermatologists. The disease of yet unknown cause starts with recurrent facial edema of short duration, which ultimately leads to persistent swelling after a period of weeks or months. METHODS: We recruited 6 patients with MM and acquired their history, routine blood tests, and individual UV light tolerability. To check for contact allergies the allergen patch test and the open epicutaneous patch test were performed. To objectify the skin conditions laser Doppler flowmetry and 20-MHz ultrasound were used. Five patients with similar symptoms, but with definitely transient facial erythema and edema caused by proven contact urticaria on cosmetics served as a comparison group. RESULTS: In all patients, routine blood tests and UVA/UVB light tests showed no pathologic results. Observations of 6 patients with MM revealed the common feature of a clinically relevant immunologic contact urticaria caused by various cosmetic ingredients, which could be diagnosed in all of them. Delayed resorption of the acute edema and prolonged inflammation were shown by laser Doppler flowmetry and 20-MHz ultrasound in the affected skin areas in patients with MM after induction of immunologic contact urticaria by a cosmetic ingredient. Strict avoidance of cosmetics yielded a remarkable clinical benefit in the follow-up examinations. CONCLUSIONS: We conclude that recurrent and possibly subclinical inflammation caused by immunologic contact urticaria in conjunction with a locally pre-existing lowered lymphatic drainage plays a crucial role in the evolution of MM.

Adult↗
PubMed2005

[Epidermal stem cells].

Current understanding of the biology of epidermal stem cells opens a totally new perspective in the function of the epidermis and adjacent epithelial structures. A number of pathogenetic as well as clinical-therapeutic approaches against a variety of dermatoses may become possible with knowledge about keratinocyte proliferation, differentiation and regeneration. The reservoir of epidermal stem cells is located in the interfollicular epidermis, the hair follicle area and the germinal hair follicle matrix. Endogenous stem cell clones exist here, giving rise to transient amplifying cells and postmitotic cells. The stem cell clones are organized in clusters and display high expression of adhesion proteins, which guarantee their stability in a specific environment consisting of different cell types and extracellular substrates in the stratum basale. Differentiation is determined by a specific cascade of chemical signals from the stem cell environment and from the genetic program of the cell. The clinical relevance of stem cells lies primarily in their therapeutic potential with reconstruction of epithelia by reimplantation of autologous stem cells or gene therapeutic applications such as targeted transfection. However, the benefit-to-risk ratio cannot yet be accurately estimated.

Animals↗
PubMed2005

Dermal delivery of desmopressin acetate using colloidal carrier systems.

Recently, the transdermal route has received attention as a promising means to enhance the delivery of drug molecules, particularly peptides, across the skin. In this work, the skin penetration profiles of desmopressin acetate from a colloidal system (water-in-oil microemulsion) and an amphiphilic cream, a standard formulation, were determined using Franz diffusion cells and compared. In the case of the microemulsion, the total percentages of dose obtained from different skin layers(stratum corneum to subcutaneous tissue) were 3.30+/-0.67, 7.37+/-2.43 and 15.54+/-2.72 at 30, 100 and 300 min, respectively. Similarly, 5.19+/-0.96, 8.04+/-0.97 and 14.4+/-5.15% of the dose applied was extracted from the skin treated with the cream. About 6% of the applied dose reached the acceptor compartment from the microemulsion instead of 2% from the cream within 300 min. The concentration of drug that penetrated into the upper layers of the skin was higher from the cream than from the microemulsion at all time intervals. On the other hand, a higher amount of drug was found in the deeper skin layers and in the acceptor compartment from the microemulsion.

Administration, Cutaneous↗
PubMed2004

Expression of epidermal N-methyl-D-aspartate receptors (NMDAR1) depends on formation of the granular layer--analysis in diseases with parakeratotic cornification.

Ionotrope glutamate receptors of the N-methyl-D-aspartate (NMDA) receptor type are expressed on keratinocytes and influence the intracellular calcium concentration. The importance of NMDA receptors in pathophysiological processes in the skin is, however, still unclear. Epidermal distribution patterns of NMDA receptors were investigated in dermatoses with parakeratotic cornification (psoriasis vulgaris and verrucae vulgares) and compared to the expression of filaggrin. The expression of NMDA receptors (R1 component) in paraffin-embedded normal epidermis (n = 22), psoriasis vulgaris (n = 21) and verrucae vulgares (n = 23) was examined and evaluated by means of digital image analysis. For quantitative characterization of the distribution patterns, a quotient was formed of the expression in the stratum granulosum and stratum basale ("NMDA ratio"). The distribution of NMDAR1 was compared to the immunohistochemical expression of filaggrin. Additionally the expression of filaggrin was investigated in HaCaT cells after treatment with the NMDA receptor antagonist MK-801. NMDA receptors were demonstrated in the epidermis of all preparations. In healthy skin, the highest receptor density was found in the stratum granulosum. This distribution pattern was basically also present in the dermatoses examined. Thus, the occurrence of parakeratosis in psoriasis vulgaris, but not in verrucae vulgares, was characterized by a significant reduction in the NMDA ratio (reduced expression of NMDAR1 in the upper epidermis). The immunohistochemical distribution of filaggrin was similar to that of NMDAR1. In HaCaT cells MK-801 suppressed the expression of filaggrin. NMDA receptors are expressed in human epidermis under physiological conditions especially in the stratum granulosum. Their reduced expression within parakeratotic epidermis in psoriasis vulgaris may be evidence of impaired intracellular calcium influx in this disease.

Cell Line↗
PubMed2004

[Two cases of frontal fibrosing alopecia in postmenopausal women].

Frontal fibrosing alopecia (FFA) is an uncommon, slowly progressive, cicatricial alopecia which mainly affects postmenopausal women. It is considered to be a variant of lichen planopilaris. We describe two postmenopausal women who developed over 11 and 24 months an asymptomatic atrophic alopecia, restricted to the frontal hairline. The diagnosis of FFA was confirmed by biopsy showing a perifollicular lymphocytic infiltrate with fibrosis. Topical corticosteroids, in one case combined with minoxidil, administered for 3 months arrested the hair loss. The treatment of FFA is often difficult. In most cases, the disease resolves spontaneously after several years. Immunomodulators such as corticosteroids and calcineurin antagonists should be tried in the early stage of FFA (frontal effluvium with perifollicular erythema) in order to arrest the disease in its inflammatory phase.

Administration, Topical↗
PubMed2004

N-methyl-D-aspartate receptors influence the intracellular calcium concentration of keratinocytes.

In the present study, the distribution of ionotropic glutamate receptors of the N-methyl-D-aspartate (NMDA)-receptor type was immunohistochemically demonstrated in healthy human skin (n = 22) and healthy buccal mucosa (n = 20). Moreover, the intracellular calcium concentration of HaCaT-cells and native human keratinocytes were studied under the influence of the selective agonist NMDA and the selective NMDA-antagonist MK-801. Immunohistochemical imaging of NMDA receptors in healthy epidermis showed a positive reaction in the stratum basale, spinosum and granulosum, whereby the greatest expression was observed in the granular layer. In the mucosal preparations, the distribution of NMDA receptors was observed to be equal in all cell layers. In the cell culture (HaCaT-cells), NMDA concentrations between 25 microM and 1 mM resulted in a significant increase in the number of cells showing elevated intracellular calcium concentration. This effect could be significantly reduced by prior application of MK-801 (100 micro M). In supplementary tests on HaCaT-keratinocytes, blockade of the keratinocytic NMDA receptors with MK-801 suppressed the differentiation of the cells (expression of cytokeratin 10). The proliferation of cells was not influenced by NMDA. The investigations showed that glutamate receptors of the NMDA type have an influence on keratinocytic calcium concentration. This appears especially important for the differentiation of keratinocytes.

Calcium↗
PubMed2002

[Reynolds syndrome--a rare combination of 2 autoimmune diseases].

HISTORY AND CLINICAL FINDINGS: Since several years, two women, 69 and 75 years of age, developed a paroxysmal blanching of the fingers on both hands. The attacks were accompanied by local pain and followed by a short period of cyanotic discoloration. INVESTIGATIONS: The diagnosis of progressive systemic sclerosis was reached by skin biopsies, immunoserological profile and significant blood vessel alteration at the proximal nail fold (capillary microscopy) in both patients. Initial esophageal sclerosis was only found in one patient. Both women were conspicuous by sonographically proven hepatomegaly, elevated hepatic serological parameters, in particular aP and GGTP. Positive AMA titers of M2 specificity and specific features in liver biopsies yielded the additional diagnosis of primary biliary cirrhosis). TREATMENT AND COURSE: One of the women was treated by pentoxifylline and nifedipine in order to improve rheology. Both received physiotherapeutic assistance. Primary biliary cirrhosis was treated with ursodeoxycholic acid which led to normalization of the cholestatic parameters. CONCLUSIONS: Reynolds' syndrome constitutes the coexistence of progressive systemic sclerosis and primary biliary cirrhosis. It remains unknown whether or not there is a constant time-related sequence of the clinical manifestations of the two immunogenetically determined disorders. However, it is remarkable that the affected elderly women described so far had Raynaud's symptoms long before the final diagnosis of Reynolds' syndrome was settled. Thus, the Raynaud's phenomenon is an early clinical symptom for the evolution of a Reynolds' syndrome. By experience, the coincidence of progressive systemic sclerosis and primary biliary cirrhosis seems to be a favorable factor concerning the progression of primary biliary cirrhosis. So, an elderly woman with recently manifested progressive systemic sclerosis should alert the physician to a concomitant primary biliary cirrhosis.

Aged↗
PubMedDate not supplied

The influence of L-arginine on the regulation of epidermal arginase.

Topical preparations containing urea are firmly established in dermatological therapy and nursing care therapy. In addition, urea is frequently used as an inactive ingredient with disinfecting, keratoplastic and penetration-promoting action in topical preparations. Despite good tolerance and ensured action, particularly the irritating effect on erosive, exudative or strongly inflammatory skin restricts its application. Endogenic urea is synthesised from L-arginine by an extra-hepatic arginase in keratinocytes. This enzymatic reaction is subject to regulation by manganese ions and the intracellular L-arginine concentration. L-Arginine is predominantly transported into the cell by a membrane transport system that is dependent on the membrane potential. By incubating keratinocyte cultures in different concentrations of L-arginine and manganese chloride, it could be shown that the keratinocytic urea synthesis can be increased. In relevant concentrations, L-arginine and manganese chloride do not exhibit any proliferation-inhibiting action, do not trigger any apoptosis or necrosis, and are stable. An increase in the expression of arginase cannot be detected using L-arginine. The application of L-arginine alone or in combination with manganese chloride increases the endogenous intrakeratinocytic urea synthesis and thus offers an option for topical therapeutic application in cases of dry skin conditions.

Apoptosis↗