PubMed Health⌕ Search

Biomedical subjects

T Vogt

Publications and source records attributed to T Vogt.

At least 19 recordsLinked to original sources
PubMed2001

Optical response of high-dielectric-constant perovskite-related oxide.

Optical conductivity measurements on the perovskite-related oxide CaCu3Ti4O12 provide a hint of the physics underlying the observed giant dielectric effect in this material. A low-frequency vibration displays anomalous behavior, implying that there is a redistribution of charge within the unit cell at low temperature. At infrared frequencies (terahertz), the value for the dielectric constant is approximately 80 at room temperature, which is far smaller than the value of approximately 10(5) obtained at lower radio frequencies (kilohertz). This discrepancy implies the presence of a strong absorption at very low frequencies due to dipole relaxation. At room temperature, the characteristic relaxation times are fast (less than or approximately 500 nanoseconds) but increase dramatically at low temperature, suggesting that the large change in dielectric constant may be due to a relaxor-like dynamical slowing down of dipolar fluctuations in nanosize domains.

Journal Article↗
PubMed2001

Transition from the layered Sr2RhO4 to the monodimensional Sr4RhO6 phase.

Study of the structural changes occurring during the reduction process of the Sr2RhO4+delta, (214), n=1 term of the Ruddlesden and Popper series, shows that for delta <0.02 values, this material dissociates into the Sr4RhO6 (416) monodimensional phase, alpha = infinity, beta = 0 compound of the (A3B2O6)alpha-(A3B3O9)beta family, and Rh metal. During the first stage, this process occurs by the formation of an intergrowth between the (214) and (416) materials which can be only detected by high resolution electron microscopy and is easily interpreted on the basis of the structural relationship established between them. Further reduction allows the segregation of both phases as separated entities, which coexist with Rh metal. The dissociation process is reversible and, under oxidizing conditions, a layered material with anionic composition delta =0.06 is always obtained. This behaviour seems to be a general way of accommodating the compositional changes in layered A2BO4 phases where the B cation is always in a octahedral environment. The structural mechanism of this transformation is proposed, and the structural relationship between these two low-dimensional oxides is established.

Journal Article↗
PubMed2001

[Paraneoplastic Bazex acrokeratosis in adenocarcinoma of the stomach].

HISTORY AND EXAMINATION: A 58-year-old man presented with a sudden eruption of hyperkeratoses on hands and feet. Alcohol abuse had been present 10 years ago, together with a gastric ulcer. Physical examination was unremarkable, except for plantar bizarre hyperkeratoses especially at the sides of the feet as well as some rhagades with spread to the dorsum of the toes. Similar but less severe hyperkeratoses were found on the palms. INVESTIGATIONS: Laboratory investigation was essentially normal. X-rays of the thorax and sinuses as well as a sonography of the stomach revealed, except for a fatty liver, no pathological findings. Gastroscopy revealed a chronic active gastritis on the small curvature of the stomach. Only a second gastroscopy and biopsy revealed an adenocarcinoma of the stomach. DIAGNOSIS, THERAPY AND COURSE: According to the clinical presentation a paraneoplastic acrokeratosis (Bazex syndrome) was diagnosed. The patient was given high-dose chemotherapy with subsequent stem-cell transplantation and gastrectomy. The skin problems resolved after the first cycles of chemotherapy. CONCLUSION: If clinically a paraneoplastic acrokeratosis is suspected extensive search for a malignancy has to be initiated, including a gastroscopy, because rarely, but as in the present case, a carcinoma of the stomach can be the underlying cause.

Adenocarcinoma↗
PubMed2001

[Intravenous immunoglobulin and prednisolone treatment of cryoglobulinemic polyneuropathy].

A 71-year-old man with cryoglobulinemia associated with severe symmetrical sensorimotor polyneuropathy was successfully treated with intravenous immunoglobulin (IVIG) and a corticosteroid. Within 2-3 months, he developed distal motor and sensory deficits and burning feet deteriorating after cold exposure. On examination, symmetric hypesthesia and hypalgesia were found along with bilateral loss of vibration and position sense, loss of ankle jerks, and paralysis of the pretibial muscles with step-page gait. The laboratory exam revealed elevated cryoglobulin levels and reduced complement C4. Nerve conduction studies were consistent with a severe axonal sensorimotor polyneuropathy. Sural nerve biopsy showed chronic neuropathy with an acute component. The patient underwent a combined treatment with prednisolone (initially 100 mg) and intravenous immunoglobulin. His condition markedly improved after almost a year of treatment. Unfortunately, the treatment with intravenous immunoglobulin had to be interrupted due to an allergic reaction after the sixth application.

Aged↗
PubMed2001

Glycosyltransferases in secondary plant metabolism: tranquilizers and stimulant controllers.

Plants are exposed to a wide range of toxic and bioactive low-molecular-weight molecules from both exogenous and endogenous sources. Glycosylation is one of the primary sedative mechanisms that plants utilise in order to maintain metabolic homeostasis. Recently, a range of glycosyltransferases has been characterized in detail with regard to substrate specificity. The next step in increasing our understanding of the biology of glycosylation will require information regarding the exact role of individual glycosyltransferases in planta, as well as an insight into their potential involvement in metabolon-complexes. Hopefully, this will answer how a large number of glycosyltransferases with broad, rather than narrow, substrate specificity can be constrained in order to avoid interfering with other pathways of primary and secondary metabolism. These and other topics are discussed.

Cytochrome P-450 Enzyme System↗
PubMed2001

Detection of differentially regulated genes in keratinocytes by cDNA array hybridization: Hsp27 and other novel players in response to artificial ultraviolet radiation.

cDNA array technology was used to identify novel genes participating in the ultraviolet response of cultured human keratinocytes. cDNA arrays representing more than 50,000 different cDNA clones were hybridized with complex probes generated by SMART-polymerase chain reaction amplification of 150 ng of total RNA extracted 24 h after ultraviolet irradiation. Fifty-one clones with differential hybridization signals were detected, representing 19 different sequences; 10 known genes (seven ultraviolet induced, three ultraviolet suppressed) and further nine expressed sequence tags of unknown genes. In seven of 10 genes the data from cDNA arrays probed with SMART-cDNA could be confirmed by northern blot analysis. The 27 kDa heat shock protein mRNA was induced. Keratins 6 and 17, markers for the hyperproliferative status of keratinocytes, were among the ultraviolet suppressed genes. The change of expression profile of keratins indicates a differentiation towards a phenotype of keratinocytes present in the suprabasal layers of the epidermis. These mechanisms may contribute to the ultraviolet protective function of the epidermis and to the anti-proliferative action of ultraviolet in the therapy of psoriasis. We also detected an induction of adenylyl cyclase associated protein and the suppression of G(s)alpha (a stimulating subunit of the trimeric membrane bound GTPase).

Blotting, Northern↗
PubMed2000

Low to high spin-state transition induced by charge ordering in antiferromagnetic YBaCo2O5

The oxygen-deficient double perovskite YBaCo2O5, containing corner-linked CoO5 square pyramids as principal building units, undergoes a paramagnetic to antiferromagnetic spin ordering at 330 K. This is accompanied by a tetragonal to orthorhombic distortion. Below 220 K orbital ordering and long-range Co(2+)/Co(3+) charge ordering occur as well as a change in the Co2+ spin state from low to high spin. This transition is shown to be very sensitive to the oxygen content of the sample. To our knowledge this is the first observation of a spin-state transition induced by long-range orbital and charge ordering.

Journal Article↗
PubMed2000

[Optimized therapy of spastic syndrome by combination intrathecal baclofen with botulinum toxin].

Intrathecal administration of baclofen has proved to be an effective treatment of spasticity related to CNS damage. Especially patients with spinal spasticity due to traumatic spinal cord injury or transverse myelitis showed a dramatic reduction of spasticity and improvement of their Ashworth scores. The results are, however, often disappointing in patients with muscular hypertension of the extensor muscles, which is frequently found in patients with multiple sclerosis or cerebral hypoxia. In the latter, using intrathecal baclofen may be restricted by serious side effects. Botulinumtoxin A is widely used in patients with various forms of dystonia. It has also been studied in spastic disorders, where local injections were valuable in relieving focal spasticity in hemiparetic patients and in infantile cerebral palsy. It is used only cautiously in severe paraspasticity. The case reports of 4 patients with incomplete and complete paraparesis due to spinal cord injury, neurodegenerative pyramidal disorder, and cerebral hypoxia demonstrate that a combination of intrathecal baclofen and botulinumtoxin A can improve clinical benefits and reduce side effects.

Adult↗
PubMed2000

Improvement of early recognition of lentigo maligna using dermatoscopy.

BACKGROUND: The clinical differentiation between lentigo senilis/initial seborrheic keratosis and lentigo maligna on the face can be difficult. OBJECTIVE: Our purpose was to determine whether dermatoscopy (eg, skin surface microscopy at 10x magnification) can reliably differentiate between these entities. METHODS: Dermatoscopic slides of 87 consecutive patients presenting 37 malignant and 50 benign pigmented skin lesions on the face were analyzed with the use of 27 dermatoscopic criteria. RESULTS: Univariate analysis selected two criteria specific for lentigo maligna: asymmetric pigmented follicular openings and dark (brown or black) rhomboidal structures. Location-specific importance in relation to facial location was attributed to the color "slate-gray, " especially in combination with structures such as dots, globules, streaks, and homogeneous areas. Multivariate analysis (logistic regression model) revealed the 4 most important features to be asymmetric pigmented follicular openings, dark rhomboidal structures, slate-gray globules, and slate-gray dots with a sensitivity of 89% and a specificity of 96%. CONCLUSION: Three conclusions can be drawn from our study: With a set of 4 dermatoscopic features, early lentigo maligna can be detected with high accuracy; dermatoscopic features on the face differ from criteria used in other locations; and our progression growth model for lentigo maligna delineates the different steps of malignant growth in lentigo maligna.

Analysis of Variance↗
PubMed2000

Glycosyltransferases in plant natural product synthesis: characterization of a supergene family.

Glycosyltransferases of plant secondary metabolism transfer nucleotide-diphosphate-activated sugars to low molecular weight substrates. Until recently, glycosyltransferases were thought to have only limited influence on the basic physiology of the plant. This view has changed. Glycosyltransferases might in fact have an important role in plant defense and stress tolerance. Recent results obtained with several recombinant enzymes indicate that many glycosyltransferases are regioselective or regiospecific rather than highly substrate specific. This might indicate how plants evolve novel secondary products, placing enzymes with broad substrate specificities downstream of the conserved, early, pivotal enzymes of plant secondary metabolism.

Amino Acid Motifs↗
PubMed2000

Sporadic Bazex-Dupré-Christol-like syndrome: early onset basal cell carcinoma, hypohidrosis, hypotrichosis, and prominent milia.

BACKGROUND: We present the case of a 32-year-old woman with a large recurrent multifocal basal cell carcinoma on the scalp. Conspicuous accompanying symptoms were multiple periorbital milia, hypotrichosis of the body and the scalp, and hypohidrosis. The sparse hair of the scalp showed further abnormalities such as pili torti, as well as flattened, irregularly curly hairs. OBJECTIVE: In 1964, Bazex et al. described a syndrome characterized by congenital hypotrichosis, follicular atrophoderma, and basocellular neoplasms that included basal cell nevi and early onset basal cell carcinomas. The Bazex-Dupré-Christol syndrome is a rare X-linked dominant disease. A sporadic occurrence with the typical constellation of these symptoms has not yet been reported. The lack of a positive family history and no signs of follicular atrophoderma argues for a sporadic occurrence of a Bazex-Dupré-Christol-like syndrome. The case reported shares several features with the classic Bazex-Dupré-Christol syndrome. CONCLUSION: Our report documents the necessity to look for early development of basal cell carcinomas in patients who show signs of the epidermal malformations described.

Acneiform Eruptions↗
PubMed2000

Rapid response of IgA pemphigus of subcorneal pustular dermatosis type to treatment with isotretinoin.

Diagnosing IgA pemphigus and distinguishing between its 2 subtypes, intraepidermal neutrophilic IgA dermatosis type and subcorneal pustular dermatosis type, is important because treatment of IgA pemphigus has to be different from treatment of other blistering autoimmune dermatoses. We present a patient with subcorneal pustular dermatosis type of IgA pemphigus who rapidly responded to systemic treatment with isotretinoin. Specific diagnosis was established by detecting IgA serum activity to desmocollin 1 by indirect immunofluorescence microscopy on unfixed COS7 cells transfected with desmocollin 1. No IgA or IgG serum reactivity was found to recombinant forms of desmogleins 1 and 3 by an antigen-specific enzyme-linked immunosorbent assay. The disease was not effectively controlled by conventional therapeutic regimens. Systemic treatment with isotretinoin 20 mg daily led to complete clearance of skin lesions within 3 weeks. Assaying IgA serum reactivity to desmocollin 1, desmoglein 1, and desmoglein 3 as a valuable method for establishing the diagnosis and differentiating the 2 subtypes of IgA pemphigus. Isotretinoin was an effective drug in the treatment of subcorneal pustular dermatosis type of IgA pemphigus in this patient.

Aged↗