Imaging and manipulation of adatoms on an alumina surface by noncontact atomic force microscopy.

Noncontact atomic force microscopy (NC-AFM) has been performed on an aluminum oxide film grown on NiAl(110) in ultrahigh vacuum (UHV) at low temperature (5 K). Results reproduce the topography of the structural model, unlike scanning tunnelling microscopy (STM) images. Equipped with this extraordinary contrast the network of extended defects, which stems from domain boundaries intersecting the film surface, can be analysed in atomic detail. The knowledge of occurring surface structures opens up the opportunity to determine adsorption sites of individual adsorbates on the alumina film. The level of difficulty for such imaging depends on the imaging characteristics of the substrate and the interaction which can be maintained above the adsorbate. Positions of single adsorbed gold atoms within the unit cell have been determined despite their easy removal at slightly higher interaction strength. Preliminary manipulation experiments indicate a pick-up process for the vanishing of the gold adatoms from the film surface.

[Effects of MRI-assayed microvascular permeability on the accumulation of vinorelbine in xenograft tumors]. / Einfluss der mittels MRT bestimmten mikrovaskulären Permeabilität auf die Akkumulation von Vinorelbine in experimentellen Xenograft-Tumoren.

PURPOSE: To determine the effects of MRI-assayed vascular leakiness on the delivery of macromolecular therapeutics to tumors. MATERIALS AND METHODS: MDA-MB 435 tumors, subcutaneously implanted into nude rats were treated with a single dose of bevacizumab at levels of 0.1 mg (n = 5) or 1.0 mg (n = 10) or received saline (control animals, n = 8). After 24 hours, albumin-(Gd-DTPA) (30)-enhanced MRI was performed. Just prior to MRI, the cytotoxic drug vinorelbine was administered intravenously. Upon completion of the MR experiment, tumor vinorelbine concentrations were quantified by high performance liquid chromatography (HPLC). Vascular leakiness (K (PS)) was calculated based on the MRI data using a pharmacokinetic model. RESULTS: K (PS) was calculated as 3.70 +/- 1.12 (control tumors), 1.95 +/- 0.70 (0.1 mg group) and 0.75 +/- 0.46 microl min (-1)cm (-3) (1.0 mg group). K (PS) was significantly higher in the control group compared to the 1.0 mg bevacizumab group. Vinorelbine concentrations were measured as 409.4 +/- 109.7 (control tumors), 387.5 +/- 47.5 (0.1 mg group) and 250.7 +/- 71.9 (1.0 mg group). These differences were not significant. A moderate and significant correlation was found between K (PS) and Vinorelbine concentrations in tumors (r = 0.49, p < 0.05). CONCLUSION: MRI-assayed K (PS) based on dynamic MRI enhanced by albumin-(Gd-DTPA) (30) correlated significantly with vinorelbine accumulation in experimental xenograft tumors under angiogenesis inhibition. Thus, the MRI technique applied in our study could potentially help to predict accumulation of macromolecular cytotoxic drugs and to optimize individual therapeutic regimes in tumors.

A portable microevaporator for low temperature single atom studies by scanning tunneling and dynamic force microscopy.

Here, we present a microevaporator setup for single adatom deposition at low temperature, which is a prerequisite for most single atom studies with scanning probe techniques. The construction of the microevaporator is based on the tungsten filament of a modified halogen lamp, covered with the required adsorbate. Very stable evaporation conditions were obtained, which were controlled by the filament current. The installation of this microevaporator on a manipulator enabled its transportation directly to the sample at the microscope kept at 5 K. In this way, the controlled deposition of Li onto Ag(100), Li, Pd, and Au onto MgO/Ag(001) as well as Au onto alumina/NiAl(110) at low temperature has been performed. The obtained images recorded after the deposition show the presence of single Li/Au atoms on the sample surfaces as a prove for successful dispersion of single atoms onto the sample surface using this technique.

Measuring the charge state of point defects on MgO/Ag(001).

A detailed understanding of surface defects is highly desirable, e.g. to clarify their role as active sites in catalysis. Here localized defects on the surface of MgO films deposited on Ag(001) are investigated. Since the electronic structure of color centers depends on their local position, spectroscopic signals are highly convoluted and often difficult to disentangle. In this study we aimed to obtain morphological and spectroscopic information on single color centers at a microscopic level with frequency modulated dynamic force microscopy (FM-DFM) and scanning tunneling microscopy (STM) in an ultrahigh vacuum and at low temperature. Four of the major and in literature mostly discussed defect types on MgO have been characterized by their charge state and finally identified by the complementary application of FM-DFM and STM in combination with density functional theory results.

[Macrophage specific MRI imaging for antigen induced arthritides. A potential new strategy for the diagnosis of rheumatoid arthritis]. / Makrophagenspezifische MRT-Bildgebung bei antigeninduzierten Arthritiden. Eine potenzielle neue Strategie für die Diagnostik der rheumatoiden Arthritis.

PURPOSE: The present work describes the potential of iron oxides for the detection of macrophages in synovitis in experimental, antigen-induced arthritis. METHODS: The pivotal role of macrophages in rheumatoid arthritis (RA) in humans and in antigen-induced arthritis (AIA) in animal models is discussed. The latter appear to be very similar in many aspects to the human RA. We show the potential for iron oxide-enhanced magnetic resonance imaging (MRI) to determine the macrophage content in the arthritic synovial membranes. The results of our own research, as well as those of other research groups, are presented and discussed. RESULTS: MRI after the intravenous (i.v.) administration of iron oxides enables the depiction of macrophage content in arthritic synovial membranes in AIA through the effects of the intracellular compartmentalisation of iron oxide particles. These effects can be demonstrated in 24-h delayed images after i.v. contrast application, on T2-weighted spin-echo or turbo-spin-echo sequences, and especially on T2*-weighted gradient-echo sequences. The signal effects are not only apparent in high field strength (4.7 Tesla) but also on 1.5 Tesla clinical scanners. CONCLUSIONS AND PERSPECTIVES: The use of iron oxides enables the determination of the macrophage content in synovitis in animals with AIA. This parameter represents a potential marker to determine disease activity, and possibly represents a marker to evaluate the effectiveness of specific therapies in human RA. Current knowledge of iron oxide-enhanced MRI is limited to animal models. The clinical evaluation of this new method in patients with RA has not yet been performed. However, based on the considerations presented here, significant progress in the diagnostic work-up of RA can be expected.

A multicentric study of 41 cases of B-prolymphocytic leukemia: two evolutive forms.

B-prolymphocytic leukemia (B-PLL) is an infrequent disease with a poor prognosis. We present the clinical and biological features of 41 patients. Median age was 67 years [42-89] and male-female sex ratio was 2.4. The immunophenotyping revealed B-cell phenotype, with a high level expression of surface IgM and/or IgD in all cases, FMC7+ in 76 % of cases and CD5+ in 67%. Marked spontaneous in-vitro apoptosis was observed in most cases tested (n = 12). The median overall survival time was 5 years and the event-free survival time was 37 months. As detected by univariate and multivariate analysis, the only variables associated with a poor prognosis were advanced age and anemia. No significant difference was observed between de novo PLL (n = 27) and prolymphocytoid transformation of chronic lymphocytic leukemia (n = 14). Two groups of patients were individualized according to their clinical course: patients who died within one year of diagnosis (n = 14) and patients who had a prolonged survival (n = 23) without any treatment in some cases. The comparison between the 2 groups showed that they differed in age (p = 0.01) and anemia (p = 0.02). We also observed that the patients with p53 mutations had a worse clinical outcome. Taken together these data confirm that B-PLL should be regarded as a distinct form of chronic lymphoproliferative disorder and suggest the existence of two patterns of clinical evolution.

PET and SPECT in whiplash syndrome: a new approach to a forgotten brain?

Whiplash associated disorders are a medicolegally controversial condition becoming increasingly worrisome in the western world. This study was designed to evaluate perfusion and glucose metabolism in whiplash brain. Using Tc-99m-bicisate (ECD) single photon emission computed tomography (SPECT) and F-18-fluorodeoxyglucose (FDG) PET, six clinically and neuropsychologically controlled patients (patient group) with whiplash syndrome and 12 normal controls (control group) were investigated. Standardised elliptical regions of interest (ROIs) were determined in three adjacent transaxial slices in the frontal, parietal, temporal, and parieto-occipital cortex, cerebellum, brain stem, basal ganglia, and thalamus. For PET, the glucose metabolic index (GMI; =ROI uptake/global uptake at the level of the basal ganglia) and, for SPECT, the perfusion index (PI; =ROI/global) were calculated. In the patient group there was significant hypometabolism and hypoperfusion in the parieto-occipital regions (on the right (R) and left (L) side) compared with the control group: PET data: GMI parieto-occipital R: control 1.066 (0.081) (mean (SD)), patient 0.946 (0.065); P=0.0092, Mann Whitney. GMI parieto-occipital L: control 1.034 (0.051), patient 0.922 (0.073); p=0.0067. SPECT data: PI parieto-occipital R: control 1.262 (0.066), patient 1.102 (0.063); P=0.0039. PI parieto-occipital L: control 1.226 (0.095), patient 1.098 (0.075); P=0.0273. In some patients there was hypometabolism (>2 SD of control) in regions other than the parieto-occipital region. It is hypothesised that parieto-occipital hypometabolism may be caused by activation ofnociceptive afferent nerves from the upper cervical spine.

Incidental appendix carcinoid. Value of somatostatin receptor imaging.

PURPOSE: Somatostatin receptor scintigraphy is used to diagnose carcinoid of the gastrointestinal tract. Its sensitivity ranges from approximately 75%-100%. Therefore, it was hypothesized that it can be used in the postsurgical follow-up to detect residual carcinoid, recurrence, and metastatic disease. RESULTS: This article is concerned with the findings of somatostatin receptor imaging performed on a 12-year-old girl 8 weeks after appendectomy. Histologic examination showed an incidental appendix carcinoid. Somatostatin receptor scintigraphy performed for detection of lymph node metastatic spread of the carcinoid showed focal tracer accumulation at the former operative site; subsequently, a right hemicolectomy was performed. However, histologic examination of the surgical tissue showed no evidence for carcinoid. CONCLUSION: It is concluded that there are some potential pitfalls for somatostatin receptor imaging at least soon after surgery. Therefore, it should not be used to aid in reoperation.

[3-phase bone scintigraphy: perfusion and vitality of the femur head after media femoral neck fracture and osteosynthesis]. / 3-Phasen-Skelettszintigraphie: Perfusion und Vitalität des Hüftkopfes nach medialer Schenkelhalsfraktur und Osteosynthese.

UNLABELLED: Perfusion and Vitality of the Femoral Head after Medial Neck Fracture and Osteosynthesis. AIMS: to analyse with regard to necrosis the perfusion and vitality of the femoral head after medial neck fracture and repair by placement of a dynamic hip screw. PATIENTS AND METHODS: Twenty-one patients were examined by scintigraphy immediately following operation as well as at 3 and 6 months postoperative for evaluation of dysfunctions of perfusion and mineralization. RESULTS: Complete perfusion and mineralization defects with a tendency for revascularization at 3 months will be normal at 6 months. Persisting dysfunctions at 3 and 6 months will progress to femoral head necrosis irrespective of the fracture staging. CONCLUSIONS: Three-phase skeletal scintigraphy is a highly sensitive, non-invasive method for evaluating perfusion and revascularization of the femoral head after femoral neck fracture and repair by means of a dynamic hip screw. When perfusion of the femoral head is observed one week after the trauma, femoral head necrosis will not arise. Immobilization is necessary after partial or complete perfusion and mineralization dysfunctions until the scintigraphic findings return to normal. The present results may serve as a recommendation for loading after fracture repair with a dynamic hip screw.

PET imaging of recurrent medullary thyroid cancer.

Medullary carcinoma of the thyroid gland is a rare tumor. Its prognosis is mainly linked to surgery, because there is no valid alternative therapy to improve patients outcome. In this report, we discuss the recurrence of such a tumor in a 64-year-old female, focusing on magnetic resonance imaging and position emission tomography evaluation of this tumor.