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Biomedical subjects

M Placzek

Publications and source records attributed to M Placzek.

At least 19 recordsLinked to original sources
PubMed2006

Perniosis-like tinea corporis caused by Trichophyton verrucosum in cold-exposed individuals.

Trichophyton verrucosum is a zoophilic infectious agent causing 98% of the dermatophytic infections of cattle. Transmission to humans has, until recently, been rare. One reason for an increase of infection in humans and animals seems to be the decrease in immunisation of cattle. We report on three cases of pertinent human infections with disseminated, sharply defined, bluish red, partly oedematous nodules and plaques in particular not only on the thighs, but also on the trunk and arms. Two of our patients work with farm animals. The third one works as an assistant in a butcher shop, but lives on a cow farm. All three patients are often exposed to the cold. In all three cases T. verrucosum was detected by culture. Tinea corporis was histologically confirmed in two patients. Based on the microbiological results, we began a combined systemic and local antimycotic therapy with fluconazole 50 mg day(-1) in two patients, itraconazole 100 mg day(-1) in one patient p.o. combined with topical ciclopiroxolamine. All patients were cured. Dermatophytosis caused by T. verrucosum can, under certain circumstances, such as frequent exposure to cold or a long-term corticosteroid therapy, mimic the characteristic clinical picture of perniosis, as we demonstrate here.

Adolescent↗
PubMed2004

Tobacco smoke is phototoxic.

BACKGROUND: Both cigarette smoke and ultraviolet (UV) radiation are known to cause changes of the skin which can be regarded as premature ageing. OBJECTIVES: To assess the theory that the effects of these two exposures could be linked by a phototoxic action of cigarette smoke. METHODS: A photohaemolysis test was used, in which human erythrocytes were incubated with cigarette smoke condensate, followed by UV irradiation and measurement of exposure-dependent haemolysis. RESULTS: Cigarette smoke condensate was clearly phototoxic. Photohaemolysis depended on the concentration of the condensate and UV dose and was more pronounced after exposure to UVA-rich than UVB-rich radiation. CONCLUSIONS: Phototoxicity may be a mechanism by which cigarette smoking causes premature skin ageing. An enhancing effect on photocarcinogenesis has also to be considered.

Adult↗
PubMed2004

Type 1 diabetes mellitus in childhood: a matched case control study in Lancashire and Cumbria, UK.

AIMS: The aim of the study was to identify environmental risk factors for insulin-dependent diabetes mellitus (Type 1 DM) in childhood. METHODS: A matched case-control study of Type 1 DM conducted in Lancashire and Cumbria, UK, using a structured interview. Cases (n=196, participation rate 83%) were children under 16 years of age diagnosed prior to October 1998 and attending diabetic clinics. Controls (n=381) were healthy children from the community matched by gender and by age (within a few days of birth). The data were analysed by logistic regression using the technique of Breslow and Day for matched case control studies. RESULTS: The multivariate regression model showed that the following factors were significantly associated with the risk of developing Type 1 DM (odds ratio, 95% confidence intervals): sharing a room with a sibling (0.458, 0.290-0.721), social contact with other children when aged 6-11 months (0.439, 0.256-0.752), consumption of sugary food (0.080, 0.024-0.261), parental insulin dependent diabetes mellitus (10.651, 3.086-36.761), maternal thyroid disease (4.861, 1.681-14.058), consuming more than one pint of milk per day prior to school entry (0.498, 0.310-0.802), maternal smoking during pregnancy (0.373, 0.218-0.636), a father with no academic qualifications (0.504, 0.278-0.913), maternal age at time of birth (0.900, 0.854-0.948), maternal infections in pregnancy (2.453, 1.011-5.948), other maternal illnesses or conditions in pregnancy (2.007, 1.139-3.535), belonging to an Asian family (0.104, 0.028-0.394), and regular contact with pets and other animals (0.552, 0.309-0.987). CONCLUSION: Many of the results are consistent with the hygiene hypothesis which links improved living standards with decreased exposure to microorganisms and increased risk of immune mediated disease in childhood. These findings challenge the idea that improved hygiene acts exclusively through a Th2 mechanism leading to atopic disease as Type 1 DM is mediated by a Th1 reaction. The association with maternal smoking could be due to recall bias but a causal link cannot be excluded with confidence.

Adolescent↗
PubMed2003

Congenital adrenal hyperplasia and acne in male patients.

Seborrhoea is one pathogenic factor for acne. Androgens induce sebum production, and excess androgen may provoke or aggravate acne. In women an androgen disorder is frequently suspected when acne is accompanied by hirsutism or menstrual irregularities. In men acne may be the only symptom of androgen excess. We report three male acne patients in whom hormonal screening revealed irregularities of androgen metabolism suggestive of late-onset congenital adrenal hyperplasia and who benefitted from low-dose glucocorticoids. Disorders of androgen metabolism may influence acne not only in women, but also in men, and these patients may benefit from low-dose glucocorticoid therapy.

Acne Vulgaris↗
PubMed2001

Vertebrate development: Et in Arkadia.

The similarities in organiser formation in Xenopus and mouse embryos have remained elusive. Recent evidence suggests a common mechanism, in which an intracellular protein, Arkadia, is required for formation of the mouse organiser and potentiates the effects of the signalling protein Nodal.

Animals↗
PubMed2000

The role of Sonic hedgehog in neural tube patterning.

In the developing neural tube of vertebrate embryos, many types of neuronal and nonneuronal cells differentiate in response to the secreted signalling molecule, Shh. Shh shows a spatially restricted pattern of expression in cells located at the ventral midline, yet governs the differentiation of diverse cell types throughout the ventral half of the neural tube. Here, we describe how the distinct fate assumed by cells in response to Shh is dependent upon their position with respect to both the dorso-ventral and anterior-posterior axes of the neural tube and describe the ways in which a single factor, Shh, is able to pattern the developing nervous system. We first discuss the evidence that Shh does impose ventral identity on cells in the neural tube, then focus on the role of a graded Shh signal in patterning the neural tube and finally discuss the interaction of Shh with other factors that affect its signalling outcome.

Animals↗
PubMed2000

Systemic vitamin C and vitamin E do not prevent photoprovocation test reactions in polymorphous light eruption.

The possible influence of oxidative stress is discussed in the pathogenesis of polymorphous light eruption (PLE). A double-blind, placebo-controlled study of prophylactic treatment with systemic administration of vitamin C (3 g/d) and E (1500 IU/d) for 8 days was undertaken in 9 patients with PLE (verum, n=4; placebo, n=5). Evaluation of the maximal effects after photoprovocation before and after intake of the antioxidants revealed a reduction of most skin reactions (overall skin reaction, papules/vesicles) in both groups with marked differences in the placebo group. The antioxidants in the doses given and over the time period used did not influence the development of PLE, but might interfere with immunosuppressive effects of repeated photoprovocation tests.

Administration, Oral↗
PubMed2000

Development of chick axial mesoderm: specification of prechordal mesoderm by anterior endoderm-derived TGFbeta family signalling.

Two populations of axial mesoderm cells can be recognised in the chick embryo, posterior notochord and anterior prechordal mesoderm. We have examined the cellular and molecular events that govern the specification of prechordal mesoderm. We report that notochord and prechordal mesoderm cells are intermingled and share expression of many markers as they initially extend out of Hensen's node. In vitro culture studies, together with in vivo grafting experiments, reveal that early extending axial mesoderm cells are labile and that their character may be defined subsequently through signals that derive from anterior endodermal tissues. Anterior endoderm elicits aspects of prechordal mesoderm identity in extending axial mesoderm by repressing notochord characteristics, briefly maintaining gsc expression and inducing BMP7 expression. Together these experiments suggest that, in vivo, signalling by anterior endoderm may determine the extent of prechordal mesoderm. The transforming growth factor (beta) (TGFbeta) superfamily members BMP2, BMP4, BMP7 and activin, all of which are transiently expressed in anterior endoderm mimic distinct aspects of its patterning actions. Together our results suggest that anterior endoderm-derived TGFbetas may specify prechordal mesoderm character in chick axial mesoderm.

Activins↗
PubMed1999

Airway patterning: A paradigm for restricted signalling.

Intercellular signalling is limited by the range of cell responsiveness, often mediated by repressors. A recently identified repressor, Sprouty, inhibits MAP kinase signalling in flies, mice and humans and has a conserved function in patterning the airways of these divergent species.

Animals↗
PubMed1999

Differential patterning of ventral midline cells by axial mesoderm is regulated by BMP7 and chordin.

Ventral midline cells in the neural tube have distinct properties at different rostrocaudal levels, apparently in response to differential signalling by axial mesoderm. Floor plate cells are induced by sonic hedgehog (SHH) secreted from the notochord whereas ventral midline cells of the rostral diencephalon (RDVM cells) appear to be induced by the dual actions of SHH and bone morphogenetic protein 7 (BMP7) from prechordal mesoderm. We have examined the cellular and molecular events that govern the program of differentiation of RDVM cells under the influence of the axial mesoderm. By fate mapping, we show that prospective RDVM cells migrate rostrally within the neural plate, passing over rostral notochord before establishing register with prechordal mesoderm at stage 7. Despite the co-expression of SHH and BMP7 by rostral notochord, prospective RDVM cells appear to be specified initially as caudal ventral midline neurectodermal cells and to acquire RDVM properties only at stage 7. We provide evidence that the signalling properties of axial mesoderm over this period are regulated by the BMP antagonist, chordin. Chordin is expressed throughout the axial mesoderm as it extends, but is downregulated in prechordal mesoderm coincident with the onset of RDVM cell differentiation. Addition of chordin to conjugate explant cultures of prechordal mesoderm and neural tissue prevents the rostralization of ventral midline cells by prechordal mesoderm. Chordin may thus act to refine the patterning of the ventral midline along the rostrocaudal axis.

Animals↗
PubMed1998

Protective effect against sunburn of combined systemic ascorbic acid (vitamin C) and d-alpha-tocopherol (vitamin E).

BACKGROUND: UV radiation causes acute adverse effects like sunburn, photosensitivity reactions, or immunologic suppression, as well as long-term sequelae like photoaging or malignant skin tumors. UV radiation induces tissues to produce reactive oxygen species, eicosanoids and cytokines. Inhibition of these mediators might reduce skin damage. Antioxidants such as ascorbic acid and d-alpha-tocopherol have been found to be photoprotective in some in vitro studies and animal experiments. OBJECTIVE: Our purpose was to assess the protective effect of systemic vitamins C and E against sunburn in human beings. METHODS: In a double-blind placebo-controlled study, each of 10 subjects took daily either 2 gm of ascorbic acid (vitamin C) combined with 1000 IU of d-alpha-tocopherol (vitamin E) or placebo. The sunburn reaction before and after 8 days of treatment was assessed by determination of the threshold UV dose for eliciting sunburn (minimal erythema dose [MED]) and by measuring the cutaneous blood flow of skin irradiated with incremental UV doses against that of nonirradiated skin. RESULTS: The median MED of those taking vitamins increased from 80 to 96.5 mJ/cm2 (p < 0.01), whereas it declined from 80 to 68.5 mJ/cm2 in the placebo group. Cutaneous blood flow changed significantly (p < 0.05) for most irradiation doses with decreases in those given vitamins and increases in the placebo group. CONCLUSION: Combined vitamins C and E reduce the sunburn reaction, which might indicate a consequent reduced risk for later sequelae of UV-induced skin damage. The increase of sunburn reactivity in the placebo group could be related to "priming" by the previous UV exposure.

Administration, Oral↗