[Cutaneous side effects of hydroxyurea treatment for polycythemia vera]. / Kutane Nebenwirkungen einer Hydroxyurea-Therapie bei Polycythaemia vera.

A 68-year-old women with polycythemia vera was treated with hydroxyurea for 8 years and developed painful ulcers on her lower legs, multiple hypertrophic actinic keratoses and a squamous cell carcinoma. After discontinuing hydroxyurea therapy the leg ulcers resolved within 8 weeks. The hypertrophic actinic keratoses and squamous cell carcinoma were treated with cryotherapy and excision, respectively. Hydroxyurea induces a variety of cutaneous side effects such as painful leg ulcers and squamous cell carcinomas. Given the wide variety of adverse cutaneous side effects associated with long-term hydroxyurea therapy, the first step in management is to insure that physicians and patients are aware of the specific risks of this treatment. Patients under hydroxyurea therapy should be monitored closely by dermatologists to early detect and treat the cutaneous side effects.

[Merkel cell carcinoma. Viral genesis and new therapeutic options?]. / Merkel-Zell-Karzinom. Virale Genese und neue Therapieoptionen?

Merkel cell carcinoma (cutaneous neuroendocrine carcinoma) is a rare, highly malignant, neuroendocrine tumor of the skin with predominance in older patients. The tumor is most often located in the sun-exposed skin of the head, the neck and -as in our patient - the extremities. Notably, the tumor bears a high risk of an early regional lymph node as well as distant metastases. Clinically, only a presumptive diagnosis of Merkel cell carcinoma can be established. The definite diagnosis is made by histological and immunohistological methods. Surgical excision with a safety margin should be combined with sentinel lymph node biopsy. In advanced tumor stages (lymph node or visceral metastasis), a remission can be achieved by different chemotherapy schedules in combination with radiation. Recently, a previously unknown polyomavirus, named Merkel cell polyomavirus (MCV or MCPyV), has been identified in 80% of Merkel cell carcinomas. In the near future, these novel findings could be utilized to distinguish Merkel cell carcinoma from small round cell cancers and could lead to the development of new therapeutic options.

[Successful use of allogeneic stem cell transplantation for treatment-refractory mycosis fungoides]. / Erfolgreicher Einsatz einer allogenen Stammzelltransplantation bei therapierefraktärer Mycosis fungoides.

Mycosis fungoides is the most common type of cutaneous T-cell lymphoma and characterized by a chronic progressive course spanning decades. The choice of treatment options should be tailored to the stage depending on the extent and aggressiveness of the disease and taking the individual situation of the patient into consideration. Long-term complete remissions can only be achieved in the early phase of the disease, while there is no therapy that results in a cure or long-term remission in advanced stages. In young patients with a treatment-refractory course of mycosis fungoides, allogeneic stem cell transplantation represents an important alternative option to manage the disease since complete clinical remission can be obtained even in advanced stages.

Novel connections between NADPH-induced lipid peroxidation and cytochrome P450 inactivation, and antioxidant and enzyme protective properties of estradiol in gonadal membranes.

This study uses microsomal membranes from rat testis tissue, including the cytochrome P450c17 (steroid 17 alpha-monooxygenase/17 alpha-hydroxyprogesterone aldolase, catalyzing the conversion of progesterone to androstenedione), to decipher the possible relation of NADPH-induced (no exogenous iron added) lipid peroxidation and cytochrome P450 inactivation and the protective effect of certain steroids. NADPH (300 microM) causes a 3.6-fold stimulation of malondialdehyde formation (thiobarbituric acid-reactive substances) and a 29% cytochrome P450c17 loss within 1 h at 37 degrees C, but has no effect on lipid peroxidation in the presence of the iron chelator desferrioxamine. Hydrogen peroxide has only marginal effects. The antioxidant efficiency of estradiol (IC50 = 13.9 microM) is higher than its cytochrome P450c17 protective efficiency (IC50 = 33.0 microM), whereas androstenedione does not inhibit lipid peroxidation but protects cytochrome P450c17 completely. The human choriogonadotropin-induced degradation of cytochrome P450c17 in incubated decapsulated testes can not be correlated with a stimulation of lipid peroxidation, and it is partially inhibited by estradiol but completely abolished by androstenedione. It is concluded (I) that NADPH stimulates iron-dependent generation of reactive oxygen species by the monooxygenase system even in the presence of certain P450 ligands in the physiological membrane environment, (II) that membrane lipid peroxidation may be suppressed by hydrophobic steroids acting as antioxidants such as estradiol, (III) that steroid ligands stabilize cytochrome P450c17 against inactivation in the presence of NADPH even if they do not act as substrates and do not possess antioxidant activity, and (IV) that the choriogonadotropin-induced down-regulation of cytochrome P450c17 is not due to accumulating steroids acting as "pseudosubstrates" as occasionally supposed.

Plasmolipin: genomic structure, chromosomal localization, protein expression pattern, and putative association with Bardet-Biedl syndrome.

Plasmolipin is a membrane protein and belongs to the tetraspan molecule (4TM) family, an expanding group of myelin proteins many of which could be linked to human hereditary demyelinating neuropathies. We have cloned and sequenced the mouse plasmolipin gene, revealing the common organization of the 4TM gene group with four exons and a large first intron. Western blot analysis with an antibody raised against the C-terminal intracellular part of the protein showed that plasmolipin is expressed not only in the nervous system and kidney, but also in a number of other tissues such as thymus, testis, lung, and thyroid gland. By means of radiation hybrid mapping and FISH analysis, we could localize the human plasmolipin gene to Chromosome 16q13 within the putative region of the Bardet-Biedl syndrome type 2 (BBS2) gene locus. BBS2 is a clinically and genetically heterogeneous group of disorders resulting in rod-cone dystrophy, obesity, postaxial polydactyly, renal dysfunction, and mental retardation, which were very recently associated with a novel gene designated BBS2. With respect to intrafamiliar variations in the manifestation of BBS, we suggest that plasmolipin might be either another candidate gene or a modifier of the BBS2 phenotype.

Cellular localization of the disintegrin CRII-7/rMDC15 mRNA in rat PNS and CNS and regulated expression in postnatal development and after nerve injury.

Disintegrins perform putative functions in cell adhesion, signaling and fusion. We have isolated a 2815-bp rat cDNA (CRII-7) representing a transcript that is differentially expressed during sciatic nerve regeneration. Nucleotide sequence comparison indicates that CRII-7 is the rat homologue to the recently cloned cDNAs MDC15 (ADAM 15) and metargidin (hMDC15) of mouse and human, respectively. The CRII-7 cDNA (rMDC15) encodes a membrane-anchored glycoprotein of approximately 85 kDa containing a disintegrin and a metalloprotease domain. Cellular metalloprotease disintegrins are a family of proteins (ADAMs or MDC proteins) with important roles, e.g., in cell-cell interactions during fertilization, muscle and nerve development, or tumor necrosis factor-alpha (TNF-alpha) cleavage. Northern blot analysis demonstrated a predominant expression of CRII-7/rMDC15 in the nervous system (PNS and CNS) and lung. Analysis of the CRII-7/rMDC15 transcript levels following peripheral nerve lesions demonstrated regulated mRNA expression during Wallerian degeneration and nerve regeneration. The steady-state levels of CRII-7/rMDC15 transcripts markedly increased within the first day after lesion and then steadily decreased for at least 4 weeks. CRII-7/rMDC15 mRNA expression was further examined during postnatal development and maturation of rat sciatic nerve and brain, as well as in cultured Schwann cells, meningeal fibroblasts, and astrocytes. In situ hybridization on paraffin sections showed the cellular localization of CRII-7/rMDC15 mRNA in Schwann cells and endothelial cells of peripheral nerve and in various neuronal populations in brain and spinal cord.