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Biomedical subjects

M Wolter

Publications and source records attributed to M Wolter.

At least 19 recordsLinked to original sources
PubMed2006

Obliquely propagating dust-density plasma waves in the presence of an ion beam.

Self-excited dust-density waves are experimentally studied in a dusty plasma under microgravity. Two types of waves are observed: a mode inside the dust volume propagating in the direction of the ion flow and a new mode propagating obliquely at the boundary between the dusty plasma and the space-charge sheath. A model for dust-density waves propagating at an arbitrary angle with respect to the ion-flow direction is presented, which explains the preference for oblique or parallel modes as a function of ion velocity.

Journal Article↗
PubMed2006

Comprehensive genomic analysis of desmoplastic medulloblastomas: identification of novel amplified genes and separate evaluation of the different histological components.

Desmoplastic medulloblastoma (DMB) is a malignant cerebellar tumour composed of two distinct tissue components, pale islands and desmoplastic areas. Previous studies revealed mutations in genes encoding members of the sonic hedgehog pathway, including PTCH, SMOH and SUFUH in DMBs. However, little is known about other genomic aberrations. We performed comparative genomic hybridization (CGH) analysis of 22 sporadic DMBs and identified chromosomal imbalances in 20 tumours (91%; mean, 4.9 imbalances/tumour). Recurrent chromosomal gains were found on chromosomes 3, 9 (six tumours each), 20, 22 (five tumours each), 2, 6, 7, 17 (four tumours each) and 1 (three tumours). Recurrent losses involved chromosomes X (eight tumours), Y (six of eleven tumours from male patients), 9, 12 (four tumours each), as well as 10, 13 and 17 (three tumours each). Four tumours demonstrated high-level amplifications involving sequences from 1p22, 5p15, 9p, 12p13, 13q33-q34 and 17q22-q24, respectively. Further analysis of the 9p and 17q22-q24 amplicons by array-based CGH (matrix-CGH) and candidate gene analyses revealed amplification of JMJD2C at 9p24 in one DMB and amplification of RPS6KB1, APPBP2, PPM1D and BCAS3 from 17q23 in three DMBs. Among the 17q23 genes, RPS6KB1 showed markedly elevated transcript levels as compared to normal cerebellum in five of six DMBs and four of five classic medulloblastomas investigated. Finally, CGH analysis of microdissected pale islands and desmoplastic areas showed common chromosomal imbalances in five of six informative tumours. In summary, we have identified several novel genetic alterations in DMBs and provide genetic evidence for a monoclonal origin of their different tissue components.

Base Sequence↗
PubMed2006

Chronic venous insufficiency - a potential trigger for localized scleroderma.

Localized scleroderma is a cutaneous disease that is characterized by an initial inflammatory response, followed by sclerosis of the skin. The cause of localized scleroderma has not yet been determined. Seifarth et al. reported two cases of localized scleroderma at sites of chronic venous insufficiency. We document here three more patients in whom localized scleroderma was located at insufficient veins. Treatment of underlying chronic venous insufficiency (CVI) leads to a substantial clinical improvement of scleroderma at the site of insufficient veins, but not elsewhere. Experimental data support the concept of chronic venous insufficiency creating a microenvironment, which may lead to localized scleroderma. Local hypoxaemia, which is present in CVI, induces the release of endothelium-derived cytokines, such as IL-1. Subsequently, expression of endothelial adhesion molecules and consequently leucocyte extravasation are induced. Infiltrating leucocytes secrete a number of inflammatory mediators, including transforming growth factor beta, which is a potent stimulus for collagen synthesis. Therefore, it may well be that CVI is a potential trigger factor for localized scleroderma. In addition, localized scleroderma may only develop if a certain amount of trigger factors are present - and resolves if one or more of the contributing factors (i.e. CVI) can be treated.

Adult↗
PubMed2006

Sodium thiosulphate as a promising therapeutic option to treat calciphylaxis.

A 35-year-old haemodialysis-dependent woman with chronic renal failure developed large, very painful necrotic ulcers and necrosis on the thighs, buttocks and the abdomen with signs of fast progression. The skin biopsy specimens showed a broad necrosis of the epidermis and thrombosed dermal vessels with focal calcium deposits within the wall. In addition, laboratory findings presented an increased product of serum calcium and phosphate concentrations. Thus, we diagnosed calciphylaxis on the basis of clinical, biochemical and histopathological criteria. We initiated a therapy in which our patient was treated with intravenous sodium thiosulphate 3 times weekly. Already after 2 weeks of treatment, no new lesions were detectable and there was a dramatic pain relief. In the following 4 weeks, a successive decline of the ulcers and the healing of individual tissue defects could be seen. Four months after the start of the therapy, the patient underwent successful renal transplantation. Thus, the intravenous therapy of calciphylaxis with sodium thiosulphate might be a new effective alternative in the treatment of this life-threatening disease.

Abdomen↗
PubMed2005

[Silica-containing urinary stones--clinical issues to keep in mind].

Formation of calculi in efferent urinary passages is always due to supersaturation of urinary calculi substances and associated increased crystallization. Apart from the typical calculi, consisting of calcium oxalate, inorganic phosphates, uric acid or cystine, there are occasional signs of rare substance classes. Although more than 50 silicate stones have already been reported internationally, this stone entity remains relatively unknown. In particular, the occurrence of silicate stones in the absence of magnesium trisilicate abuse is extremely rare. A medium-sized left-sided ureterolith was removed from a 54-year-old male patient using a ureteroscope. X-ray diffraction showed it to be a compound stone consisting of 40% silicate. The patient, who in 1986 was living close to the nuclear reactor accident in Chernobyl, showed no signs of a constant uptake of magnesium trisilicate. However, he had undergone partial (2/3) gastrectomy 4 months before for a drug-refractory gastric ulcer, which had been diagnosed at the end of the 1980s and treated with excessive dosages of a magnesium trisilicate antacid preparation until the time of the operation. The patient had also been suffering from unstable angina pectoris since 1986 and treated with Pentalong (pentaerythrityltetranitrate) for 17 years. We were also able to detect silicium dioxide in components of this drug using X-ray diffraction. Silicate uroliths are extremely rare but they can be clearly identified by X-ray diffraction or infrared spectroscopy and distinguished from artifacts or quartz pebbles. Formation of calculi can be prevented by increasing diuresis as well as switching to a different drug and reducing the dosage.

Angina, Unstable↗
PubMed2005

Somatic mutations in the PTCH, SMOH, SUFUH and TP53 genes in sporadic basal cell carcinomas.

BACKGROUND: Basal cell carcinoma (BCC) of the skin is the most common human cancer. The genetic alterations underlying BCC development are only partly understood. OBJECTIVES: To investigate further the molecular genetics of sporadic BCCs, we performed mutation analyses of 10 skin cancer-associated genes in 42 tumours. METHODS: Single-strand conformational polymorphism analysis followed by DNA sequencing was used to screen for mutations in the sonic hedgehog pathway genes PTCH, SMOH, SUFUH and GLI1, in the TP53 tumour suppressor gene, and in the proto-oncogenes NRAS, KRAS, HRAS, BRAF and CTNNB1. Microsatellite markers flanking the PTCH, SUFUH and TP53 loci at 9q22, 10q24 and 17p13, respectively, were studied for loss of heterozygosity (LOH). RESULTS: PTCH mutations were found in 28 of 42 tumours (67%). Microsatellite analysis revealed LOH on 9q22 in 20 of 38 tumours investigated (53%), including 14 tumours with and six tumours without PTCH mutations. SMOH mutations were identified in four of the 42 BCCs (10%) while two tumours demonstrated mutations in SUFUH, including one missense mutation and one silent mutation. None of the BCCs showed LOH at markers flanking the SUFUH locus. Seventeen BCCs (40%) carried TP53 mutations, with only three tumours showing evidence of biallelic TP53 inactivation. TP53 mutations were present in BCCs with and without mutations in PTCH, SMOH or SUFUH. Interestingly, 72% of the TP53 alterations were presumably ultraviolet (UV)-induced transition mutations. In contrast, only 40% of the PTCH and SMOH alterations corresponded to UV signature mutations. No mutations were identified in GLI1, NRAS, KRAS, HRAS, BRAF or CTNNB1. CONCLUSIONS: Our data confirm the importance of PTCH, SMOH and TP53 mutations in the pathogenesis of sporadic BCCs. SUFUH alterations are restricted to individual cases while the other investigated genes do not appear to be important targets for mutations in BCCs.

Adult↗
PubMed2004

Melting and heating of two-dimensional Coulomb clusters in dusty plasmas.

The heating and melting of two-dimensional dust clusters with one additional particle in the lower layer has been investigated experimentally in a gas discharge. The full dynamical properties of the system during the entire phase transition were determined in terms of the spectral power densities of the crystal modes. A two-step melting transition is identified when the gas pressure in the discharge is reduced: first, a sudden increase of the dust temperature takes place due to an instability of the lower-layer particle resulting in a hot crystalline state of the cluster, and second, the actual transition into a fluid state is observed at a decisively lower gas pressure.

Journal Article↗
PubMed2003

[Perianal abcess in infant].

INTRODUCTION: Perianal abcess and fistula-in-ano are particular when happening in infants of less than 1 year of age. A congenital abnormality of crypts of Morgagni may be at the origin of the disease. There is no evidence for predisposing condition at this age. CASE REPORT: A 7-week-old boy had a painful swollen perianal lesion suggesting the presence of perianal abcess. Biological tests did not show any neutropenia nor inflammatory syndrome. The infant was admitted to the surgical center to undergo a perianal abcess drainage. During the intervention, no fistula was found. No recurrence was observed. DISCUSSION: Perianal abcess and/or fistula-in-ano are relatively common conditions in infants of less than 1 year of age. This disease is suspected to originate from anal cryptitis, which will later form a perianal abcess. Androgen excess during the foetal stage could be the cause of the formation of abnormal crypts of Morgagni, which encourages cryptitis and abcess formation. In childhood some predisposing factors can exist, as immunodeficiency or colopathy. On the opposite, a predisposing condition is rare in infancy. Twenty-eight to 85 per cent of infants with perianal abcess may progress to form a fistula. The usual treatment of perianal abcess is incision and drainage; it may be completed by fistulotomy or fistulectomy. The antibiotherapy is not systematic. The identification of the corresponding crypt may be important to avoid recurrence. On the opposite, a recent prospective study proposes a non operative management of perianal abcess and fistula-in-ano in healthy infants.

Abscess↗
PubMed2002

[Criteria of dignity in ultrasound mammography using a 10-MHz-transducer, also with regard to tumor size].

AIM: Ongoing technical progress has increased the accuracy of imaging in ultrasound mammography. Using a 10-MHz-transducer, eight different criteria of dignity were evaluated for validity, also with regard to the size of a tumor. MATERIALS AND METHODS: Over a period of three years, 446 breast tumors were ultrasonographically examined by two experienced medical doctors. The study comprised only suspicious lesions detected by mammography and/or manual palpation. Diagnostic validity was quantified by means of sensitivity, specificity, positive and negative predictive value, as well as the ODDS-ratio. RESULTS: Ultrasound mammography demonstrated a sensitivity of 94.0 %, specificity of 91.4 %, positive predictive value of 95.9 %, and a negative predictive value of 99.1 %. Eight different sonographic criteria were validated separately. The most important signs of malignancy were (in descending order): a highly echogenic halo, spikes, jagged contour, posterior acoustic shadowing, and discontinuity of tissue structure. Features of benign disease were: smooth edge, posterior acoustic enhancement, displacement margin, bilateral acoustic shadowing and continuity of tissue structure. Furthermore, it appeared that the size of a tumor only had consequences on posterior shadowing (p = 0.017). All other features did not show significant variation in relation to tumor size. CONCLUSION: We were able to prove that ultrasound mammography is an excellent medium for the differentiation of benign and malignant breast lesions, when precise indication criteria were adhered to, even in cases of small tumor size.

Adolescent↗
PubMed2002

[Intravascular large cell lymphoma revealed by diffuse telangiectasia and cauda equina syndrome].

BACKGROUND: Intravascular lymphoma is a rare disease with usually fatal outcome, characterized by the proliferation within the lumen of small blood vessels of neoplastic large lymphoid cells of B-cell origin. We report a case of intravascular lymphoma revealed by diffuse telangiectasia and cauda equina syndrome. CASE REPORT: A 64-year-old Vietnamese woman presented with unexpected fever and weight loss. Three months after the onset of the first symptoms, an oedema appeared on the lower limbs and the trunk, followed by the eruption of diffuse superficial telangiectasia. Neurologic examination revealed a cauda equina syndrome. The diagnosis of intravascular B cell lymphoma was established on cutaneous and muscular biopsy specimen. A moderate hemophagocytic syndrome was observed, confirmed by bone marrow biopsy. Corticosteroid therapy was started, followed by combination chemotherapy yielding complete response. Six months later death occurred, without evidence of relapse of intravascular lymphoma. DISCUSSION: Clinical presentation of intravascular lymphoma is often confusing, mimicking systemic disease, with a predilection for skin and nervous system involvement. Diagnosis is difficult and often an autopsy finding. Prognosis is generally poor, but favourable responses to chemotherapy have been observed after early diagnosis and treatment. The pathogenesis of intravascular lymphoma remains unknown. Dysfunction of cell-endothelial interaction affecting adhesion molecules has been suspected. The implication of Epstein-Barr virus in intravascular lymphoma remains controversial.

Female↗
PubMed2001

Synthesis of N-aryl hydrazides by copper-catalyzed coupling of hydrazides with aryl iodides.

[reaction--see text] A convenient method for intermolecular N-arylation of hydrazides with substituted aryl iodides in the presence of a copper catalyst and Cs(2)CO(3) is reported. The C-N coupling of N-Boc hydrazine with para- and meta-substituted aryl iodides afforded the N-arylated products A, regioselectively. A reversal in regioselectivity is observed for the arylation of benzoic hydrazide with ortho-substituted aryl iodides, providing the N'-arylated products B.

Benzene Derivatives↗
PubMed2001

Somatic mutations of WNT/wingless signaling pathway components in primitive neuroectodermal tumors.

Primitive neuroectodermal tumors (PNETs) represent the most frequent malignant brain tumors in childhood. The majority of these neoplasms occur in the cerebellum and are classified as medulloblastomas (MB). Most PNETs develop sporadically; however, their incidence is highly elevated in patients carrying germline APC gene mutations. The APC gene encodes a central component of the WNT/wingless developmental signaling pathway. It regulates the levels of cytoplasmic beta-catenin protein that plays a central role in neural development and cell proliferation. We analyzed 87 sporadic PNETs and 10 PNET cell lines for mutations of the APC gene and beta-catenin (CTNNB1) gene using single strand conformational polymorphism (SSCP) and sequencing analysis. We examined the mutation cluster region of APC (codons 1255--1641) for germline variants and somatic mutations. The medulloblastoma cell line MHH-MED-2 carried a Glu1317Gln missense germline variant and a sporadic MB sample showed a somatic Pro1319Leu substitution. Mutational analysis of exon 3 of CTNNB1 uncovered 4 PNETs (4.8%) with somatic missense mutations. These mutations caused amino acid substitutions in 3 of 80 medulloblastomas (Ser33Phe, Ser33Cys and Ser37Cys) and 1 of 4 supratentorial PNETs (Gly34Val). All mutations affected GSK-3 beta phosphorylation sites of the degradation targeting box of beta-catenin and resulted in nuclear beta-catenin protein accumulation. Deletions of CTNNB1 were not detected by PCR amplification with primers spanning exons 1--5. Our data indicate that inappropriate activation of the WNT/wingless signaling pathway by mutations of its components may contribute to the pathogenesis of a subset of PNETs.

Adenomatous Polyposis Coli Protein↗
PubMed2001

Analysis of human meningiomas for aberrations of the MADH2, MADH4, APM-1 and DCC tumor suppressor genes on the long arm of chromosome 18.

We have previously reported that losses of genomic material from the long arm of chromosome 18 are frequent in atypical and anaplastic meningiomas but rare in benign meningiomas. In the present study, we have investigated a series of 37 meningiomas for mutation and expression of 4 tumor suppressor genes (MADH2, MADH4, APM-1 and DCC) located at 18q21. Comparative genomic hybridization or loss of heterozygosity analysis showed losses on chromosome 18 that included sequences from 18q21 in 15 of 37 tumors. Mutation analysis of APM-1 revealed a missense mutation (c. 1819G>A: G607S) in 1 atypical meningioma. None of the tumors showed mutations of MADH2 and MADH4 or loss of detectable transcripts from MADH2, MADH4, APM-1 and DCC. In contrast to human brain tissue, normal leptomeninges and meningiomas showed preferential expression of a DCC splice variant lacking 60 base pairs from exon 17. Taken together, our data do not support a significant role for MADH2, MADH4, APM-1 and DCC alterations in the pathogenesis of meningiomas. The targeted gene that is inactivated in most meningiomas with 18q losses remains to be identified.

Adiponectin↗
PubMed2001

[Plantar fibromatosis with marked cutaneous involvement].

Cutaneous involvement in plantar fibromatosis is very rare. The classical finding are nodules in the plantar arch, which can be detected only with palpation. A 55 year-old man presented with a 3 year history of painful plantar nodules and an ulceration. Histopathology showed a fibroblastic proliferation with a pseudosarcomatous configuration. The immunohistochemistry was positive for vimentin, alpha-actin and desmin, a pattern which characterizes a myofibroblast. Intralesional therapy with corticosteroids did not reduce the lesions. After surgical treatment, the lesions recurred.

Fibroma↗
PubMed2001

[Papular acantholytic dyskeratosis].

Papular acantholytic dyskeratosis is a very rare skin disease, which shows a suprabasilar cleft with acantholytic and dyskeratotic cells, simulating the light microscopic picture of Darier disease. In this condition, the lesions are acquired without a genetic basis. We observed a 40-year-old woman with about 200 papules on the lower aspects of her legs; histological examination showed changes similar to Darier disease. Transmission electron microscopy showed a reduced number of desmosomes and perinuclear distribution of tonofilaments. The lesions were successfully treated with cryotherapy with spray technique.

Acantholysis↗
PubMed2001

Molecular genetic alterations in glioblastomas with oligodendroglial component.

Glioblastoma multiforme is the most malignant astrocytic glioma and usually resistant to chemotherapy. A small fraction of glioblastomas may contain areas with histological features of oligodendroglial differentiation. To determine the molecular genetic alterations in such "glioblastomas with oligodendroglial component", we investigated 13 of these tumors for genetic alterations and/or expression of the TP53, CDKN2A, PTEN, and EGFR genes. In addition, we performed microsatellite analyses for loss of heterozygosity (LOH) on chromosome arms 1p, 19q and 10q. None of tumors showed evidence for LOH on 10q. LOH on 1p was detected in 3 tumors, 1 of which additionally showed LOH on 19q. The 3 tumors with LOH on 1p showed neither TP53 mutations nor nuclear p53 accumulation. In contrast, 9 of 10 tumors without demonstrated losses on 1p showed nuclear p53 accumulation. TP53 mutations were identified in 3 of these cases. Further aberrations detected were epidermal growth factor receptor (EGFR) overexpression (3 of 13 tumors), homozygous CDKN2A deletion (2 of 11 tumors), and PTEN mutation (1 of 13 tumors). Taken together, our results indicate that "glioblastomas with oligodendroglial component" carry heterogeneous genetic alterations. LOH on 10q, PTEN mutation, and homozygous CDKN2A deletion appear to be less common in these tumors as compared to ordinary glioblastomas. Furthermore, a subset of these tumors demonstrates LOH on 1p, i.e., an alteration that has recently been linked to chemosensitivity and good prognosis in anaplastic oligodendrogliomas.

Adult↗