Biomedical subjects
S Roth
Publications and source records attributed to S Roth.
Raman spectrum of graphene and graphene layers.
Graphene is the two-dimensional building block for carbon allotropes of every other dimensionality. We show that its electronic structure is captured in its Raman spectrum that clearly evolves with the number of layers. The D peak second order changes in shape, width, and position for an increasing number of layers, reflecting the change in the electron bands via a double resonant Raman process. The G peak slightly down-shifts. This allows unambiguous, high-throughput, nondestructive identification of graphene layers, which is critically lacking in this emerging research area.
Raman active phonons of identified semiconducting single-walled carbon nanotubes.
The resonant Raman spectra of (n, m) semiconducting single-walled carbon nanotubes, unambiguously identified from their electron diffraction patterns, have been measured. The diameter dependence of the frequency of the tangential modes with A symmetry has been obtained in the diameter range from 1.4 to 2.5 nm. The comparison between the excitation energies and the calculated transition energies allowed us to determine precisely the values of the Es33 and Es44 transition energies. Finally, in the debate concerning the dominant process at the origin of the first-order Raman scattering in single-walled carbon nanotubes (single resonance process or double resonance process), our results are well understood in the framework of a single resonance process.
Nodal peripheral T-cell lymphomas correspond to distinct mature T-cell populations.
Peripheral T-cell lymphomas (PTCL) have not been successfully correlated with specific developmental stages of reactive T-cells. Mature T-cells pass through distinct stages upon antigen encounter. Naïve T-cells are CD45RA(+)/CD45R0(-)/CD27(+)/CCR7(+). After antigen contact they replace CD45RA expression with CD45R0. The mature T-cells differentiate to central memory cells, which retain CD27 and CCR7, or to effector memory cells, which lose expression of both molecules depending on the strength of the antigen interaction. In this study, we evaluated lymph node biopsies from eight PTCL-not otherwise specified (PTCL-NOS), seven angioimmunoblastic T-cell lymphomas (AILT), and 15 anaplastic large cell lymphomas (ALCL). Detection of tumour cells with antibodies that recognize specific rearranged T-cell receptor Vbeta segments allowed us to investigate the expression of various differentiation-associated molecules. Results were analysed by hierarchical cluster analysis. All AILT and ALCL showed a homogeneous effector cell phenotype (CD45RA(-)/CD45R0(+)/CD27(-)), but differed in the cytotoxic and activation markers expressed. Several (5/8) PTCL-NOS clustered together; these cases all exhibited a CD4(+) central memory cell phenotype (CD45RA(-)/CD45R0(+)/CD27(+)) and four expressed the lymph node homing receptor CCR7. In conclusion, AILT and ALCL tumour cells correspond to different subsets of effector cells, while a subset of PTCL-NOS correlates with a non-effector T-cell population.
[Noninvasive and invasive bladder cancer: diagnostics and treatment].
Therapy of superficial bladder tumors is transurethral resection (TUR), and in cases of pT1 or high-grade tumors a re-TUR is indicated. Patients with carcinoma in situ receive intravesical chemotherapy or BCG for at least 3 months. Persistent carcinoma in situ may be treated by radical cystectomy. With the provision of a functionally adequate urinary diversion, cystectomy represents an effective treatment for patients with muscle-invasive bladder cancer without metastatic spread. Regional lymph node metastases can be found in up to 15% of stage T1 disease and are present in 33% of stage T3/4 lesions. Thus, lymphadenectomy gains diagnostic and possibly also therapeutic importance. For selected patients, who cannot be treated by radical cystectomy, multimodal concepts aiming to preserve the bladder are discussed. After or prior to cystectomy systemic chemotherapy may become necessary for some patients to positively affect the course of the disease in cases of locally advanced or metastatic lesions.
Fabrication of single-walled carbon-nanotube-based pressure sensors.
We report on the fabrication and characterization of bulk micromachined pressure sensors based on individual single-walled carbon nanotubes (SWNTs) as the active electromechanical transducer elements. The electromechanical sensor device consists of an individual electrically connected SWNT adsorbed on top of a 100-nm-thick atomic layer deposited (ALD) circular alumina (Al(2)O(3)) membrane with a radius in the range of 50-100 microm. A white light interferometer (WLI) was used to measure the deflection of the membrane due to differential pressure, and the mechanical properties of the device were characterized by bulge testing. Finally, we performed the first electromechanical measurements on strained metallic SWNTs adhering to a membrane and found a piezoresistive gauge factor of approximately 210 for metallic SWNTs.
Nano-electromechanical displacement sensing based on single-walled carbon nanotubes.
We present a nano-electromechanical system based on an individual single-walled carbon nanotube (SWNT) demonstrating their potential use for future displacement sensing at the nanoscale. The fabrication and characterization of the proposed nanoscaled transducer, consisting of a suspended metal cantilever mounted on top of the center of a suspended SWNT, is presented and discussed. The displacement of the nanoscale cantilever is detected via the electromechanically induced change in conductance of the strained SWNT. A relative differential resistance sensitivity (for a metallic SWNT) of up to 27.5%/nm was measured and a piezoresistive gauge factor of a SWNT of up to 2900 was extracted.
[Cervical cerebrospinal fluid fistula after whiplash injury--treatment using CT-guided autologous blood injection].
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Images in neonatal medicine. Fatal newborn head enlargement: high resolution magnetic resonance imaging at 4.7 T.
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[Paraneoplasic multicentric reticulohistiocytosis associated with a celiac disease].
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Vanishing of the Breit-Wigner-Fano component in individual single-wall carbon nanotubes.
In order to decide definitely on the dependence of the intensity of the Breit-Wigner-Fano (BWF) component with the size of the bundle, we have measured the radial breathing modes and tangential modes (TMs) of well defined metallic individual single-wall carbon nanotubes (SWCNTs) and individual SWCNT bundles. In this aim, a complete procedure including the preparation of the substrates, the sample preparation, atomic-force-microscopy imaging and Raman spectroscopy has been developed. From this procedure, we show unambiguously that the BWF component vanishes in isolated metallic SWCNTs. In other words, the observation of a BWF component in the TM bunch is an intrinsic feature of the metallic SWCNT bundle.
Effect of chemical treatment on electrical conductivity, infrared absorption, and Raman spectra of single-walled carbon nanotubes.
We investigate the magnitude and temperature dependence of electrical conductivity, the optical and infrared absorption, and the Raman spectra of single-walled carbon nanotube (SWNT) bucky-paper after chemical treatment and determine the correlations between the changes in these properties. Ionic-acceptor doping of the SWNT bucky-paper (with SOCl(2), iodine, H(2)SO(3), etc.) causes an increase of electrical conductivity that correlates with an increase of the absorbance in the far-IR region and an increase in the frequency of Raman spectral lines. Conversely, treatment with other molecules (e.g., aniline, PyPhF(5), PhCH(2)Br, etc.) leads to a decrease in both conductivity and far-IR absorption. The temperature dependence of the conductivity gives a good indication of the presence of metallic charge carriers and is in agreement with the model of interrupted metallic conduction.
[Standard procedures in hemodialysis shunt surgery].
Native arteriovenous (AV) fistula are the first choice for primary hemodialysis access. It is essential to save as much vein as possible, and therefore distal AV shunts should be tried first. In patients with diabetes, primary brachiocephalic shunts are indicated and show better results than distal AV fistulae. The major complication of AV fistulae is shunt thrombosis. Immediate surgical repair is necessary, with the aim of preserving enough puncture sites to allow prompt continuation of the hemodialysis therapy. It is important to avoid central venous catheters, because these cause infectious complications more frequently. Shunt infections occur more often in polytetrafluoroethylene grafts than in native AV fistulae and represent a life-threatening situation for dialysis patients.
[A diagnosis drawn from hair].
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Transparent and flexible carbon nanotube transistors.
We report the fabrication of transparent and flexible transistors where both the bottom gate and the conducting channel are carbon nanotube networks of different densities and Parylene N is the gate insulator. Device mobilities of 1 cm(2) V(-1) s(-1) and on/off ratios of 100 are obtained, with the latter influenced by the properties of the insulating layer. Repetitive bending has minor influence on the characteristics, with full recovery after repeated bending. The operation is insensitive to visible light and the gating does not influence the transmission in the visible spectral range.
[Are there indications for organ-preserving tumor resection in urothelial cancers of the upper urinary tract?].
PURPOSE: Identification of prognostic factors for tumor recurrence in nephronsparing surgery and tumor progression after organ-preserving surgery. MATERIAL AND METHODS: From June 1989 to February 2003, 43 patients (47 nephron units) underwent organ-preserving surgery or the upper urinary tract because of urothelial carcinoma, with 26 (60.5 %) having an elective indication (healthy contralateral kidney). RESULTS: The mean follow-up was 39.2 months with a range of 10.6 to 168.3 months. Ipsilateral recurrences occurred in 13 (27.6 %) of reno-ureteral units. Recurrences were significantly more common for tumors located in the renal pelvis or opposite the ureteral origin (p = 0.018). Tumor progression occurred in 8 of 43 patients (18.6 %) and significantly correlated with the T- and G-stage of the primary tumor (p = 0.006 and p = 0.002). Of the 47 conservatively treated reno-ureteral units, 38 (80.8 %) could be preserved. CONCLUSION: Organ-preserving resection of the urothelial carcinoma of the upper urinary tract is an alternative in some patients with well-differentiated superficial tumors. A follow-up for life and a good patient compliance are necessary. Tumors of the renal pelvis have a significantly higher recurrence rate than ureteral tumors. Poorly differentiated tumors should undergo organ-preserving surgery only if the goal is palliation and in patients with solitary kidney after intensive consultation about the high risk of invasive recurrences and the development of metastases.
Extrafollicular proliferation of B cells in the absence of follicular hyperplasia: a distinct reaction pattern in lymph nodes correlated with primary or recall type responses.
AIMS: Extrafollicular activation of B cells is rarely observed in human lymph nodes. The aim of this study was to extensively analyse the expression of surface molecules and transcription factors in four such cases, comparing them with follicular B cells and medullary cord plasma cells. METHODS AND RESULTS: Various combinations of B-cell-related surface markers and transcription factors were studied by triple immunofluorescence. While in the germinal centre, reactive immunoglobulin production occurred exclusively in non-proliferating cells, in extrafollicular activation proliferation of B cells and immunoglobulin production coexisted. In two of these cases proliferating cells were mainly IgG+CD27+, i.e. derived from class-switched postgerminal centre memory B cells. Some of these cells expressed CD30. In the other two cases, immunoglobulin-forming cells were non-class-switched IgM+CD27- B cells, representing a primary expansion of naive B cells. CONCLUSIONS: Extrafollicular B-cell activation is the morphological correlate of rapid B-cell responses that do not involve the germinal centres. It is pathogenetically heterogeneous, comprising primary responses that occur prior to, or independent of, germinal centre reaction or memory cell activation in recall responses.
[Ureterectomy with bladder cuff -- in open and laparoscopic nephroureterectomy].
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