Synthesis and Optical Characterization of a Rhodamine B Spirolactam Dimer.

Amide derivatives of xanthene dyes such as rhodamine B are useful in a variety of sensing applications due to their colorimetric responses to stimuli such as acidity changes and UV light. The optical properties of these molecules can be influenced by intermolecular associations into dimeric structures, but the exact impact can be hard to predict. We have designed a covalently linked intramolecular dimer of the dye rhodamine B utilizing p-phenylenediamine to link the two dyes via amide bonds. The doubly closed spirolactam version of this dimer, RSL2, is isolated as a colorless solid. Under acidic conditions or UV exposure, RSL2 solutions develop a pink color that is expected for the ring-opened form of the molecule. However, nuclear magnetic resonance (NMR) and single-crystal diffraction data show that the equilibrium still prefers the closed dimer state. Interestingly, the emission profile of RSL2 shows solvatochromic blue fluorescence. Control studies of model compounds with similar structural motifs do not display similar blue fluorescence, indicating that this optical behavior is unique to the dimeric form. This behavior may lend itself to applications of such xanthene dimers to more sophisticated sensors beyond those with traditional binary on/off fluorescence profiles.

Precision Spectroscopy of Negative-Ion Resonances in Ultralong-Range Rydberg Molecules.

The level structure of negative ions near the electron detachment limit dictates the low-energy scattering of an electron with the parent neutral atom. We demonstrate that a single ultracold atom bound inside a Rydberg orbit forming an ultralong-range Rydberg molecule provides an atomic-scale system that is highly sensitive to electron-neutral scattering and thus allows for detailed insights into the underlying near-threshold anion states. Our measurements reveal the so-far unobserved fine structure of the ^{3}P_{J} triplet of Rb^{-} and allows us to extract parameters of the associated p-wave scattering resonances that deviate from previous theoretical estimates. Moreover, we observe a novel alignment mechanism for Rydberg molecules mediated by spin-orbit coupling in the negative ion.

Control of multiple excited image states around segmented carbon nanotubes.

Electronic image states around segmented carbon nanotubes can be confined and shaped along the nanotube axis by engineering the image potential. We show how several such image states can be prepared simultaneously along the same nanotube. The inter-electronic distance can be controlled a priori by engineering tubes of specific geometries. High sensitivity to external electric and magnetic fields can be exploited to manipulate these states and their mutual long-range interactions. These building blocks provide access to a new kind of tailored interacting quantum systems.

Mutation in the gene encoding ferritin light polypeptide causes dominant adult-onset basal ganglia disease.

We describe here a previously unknown, dominantly inherited, late-onset basal ganglia disease, variably presenting with extrapyramidal features similar to those of Huntington's disease (HD) or parkinsonism. We mapped the disorder, by linkage analysis, to 19q13.3, which contains the gene for ferritin light polypeptide (FTL). We found an adenine insertion at position 460-461 that is predicted to alter carboxy-terminal residues of the gene product. Brain histochemistry disclosed abnormal aggregates of ferritin and iron. Low serum ferritin levels also characterized patients. Ferritin, the main iron storage protein, is composed of 24 subunits of two types (heavy, H and light, L) which form a soluble, hollow sphere. Brain iron deposition increases normally with age, especially in the basal ganglia, and is a suspected causative factor in several neurodegenerative diseases in which it correlates with visible pathology, possibly by its involvement in toxic free-radical reactions. We found the same mutation in five apparently unrelated subjects with similar extrapyramidal symptoms. An abnormality in ferritin strongly indicates a primary function for iron in the pathogenesis of this new disease, for which we propose the name 'neuroferritinopathy'.

The effects of parathyroid hormone (PTH) and PTH-related peptide on osteoclast resorption of bone slices in vitro: an analysis of pit size and the resorption focus.

The mechanism whereby PTH, a potent stimulator of bone resorption, may under certain circumstances exert anabolic effects on bone is not known, but it is possible that it involves reduction of the size of osteoclast resorption lacunae. We have therefore made a detailed in vitro study of the effects of PTH and PTH-related peptide (PTHrP) on resorption by neonatal rat osteoclasts paying particular attention to the plan area of resorption pits. In order to distinguish between increased resorption at a particular site and increased numbers of sites, we have used an eyepiece graticule to define a focus of resorption, namely an area occupying 1/116th of the bone slice, which may contain either one or several pits. In addition we have studied the relationship between the number of pits in a resorption focus and the total area of bone resorbed at the focus. We found that PTH and PTHrP, at doses between 2 x 10(-10) M and 2 x 10(-8) M, while exerting significant stimulatory effects on bone resorption, caused a reduction in the median plan area of pits. An increase in the number of resorption foci was the primary stimulatory effect of PTH and PTHrP, occurring within 6 h in the case of PTH. However, the plan area of bone resorbed at a focus showed no significant increase, despite an increase in the number of pits per focus, because as more pits were formed at a focus, the pits were smaller, thus partially dissipating the stimulatory effect of PTH on resorption. These results are consistent with the activation of new remodeling sites by PTH in vivo. Furthermore, the formation of smaller pits under the resorptive influence of PTH may, together with the maintenance of coupling between formation and resorption, play a role in the preservation of cancellous bone recorded in cases of primary hyperparathyroidism and the anabolic effect of exogenous PTH.

Dual photon absorptiometric measurements of bone mineral density increase with source life.

Results from Dual Photon Absorptiometry, a common tool in the assessment of bone mass, vary as a function of source life, increasing by as much as 0.6% per month. This rate of increase may vary with source, and its cause is not clear. However, this long-term "drift" must be considered a significant problem for longitudinal studies and regular standardization of DPA equipment, in addition to calibration to machine standards, may be required for stringent quality control.

Possible causes of inconclusive results on CT-guided thoracic and abdominal core biopsies.

OBJECTIVE: We sought to determine possible technical causes of inconclusive results on CT-guided core biopsies of lesions suggestive of malignancy and to determine the frequency with which such lesions are eventually found to be malignant. MATERIALS AND METHODS: We retrospectively reviewed 116 consecutive CT-guided thoracic and abdominal core biopsies performed with a 20-gauge automatic biopsy system. Biopsy results were conclusive (n = 94) if pathology confirmed malignancy and inconclusive (n = 22) if pathology results were negative for malignancy or were nondiagnostic. Lesion volume, location, number of cores, and biopsy technique (paraxial or coaxial) were compared for the conclusive and inconclusive biopsy results. Malignancy within the group of inconclusive biopsy results was determined from a second biopsy, radiographic follow-up, or surgery. RESULTS: Regression analysis identified only the biopsy method as a significant factor affecting biopsy outcome: The paraxial method was more likely to yield a conclusive result than the coaxial method (p < .002). For the two biopsy methods, lesions had similar volumes, locations, and numbers of cores obtained. For single core biopsies, both methods were equivalent. However, if two or more cores were obtained, a conclusive result was achieved in more than 90% of biopsies with the paraxial method versus 65% for the coaxial method. On follow-up, results of 14 (64%) of 22 inconclusive biopsies were malignant, indicating an overall false-negative rate of 12%. CONCLUSION: CT-guided core biopsy performed with 20-gauge automatic biopsy systems and the paraxial method will yield conclusive results significantly more often than the coaxial method. In the event of inconclusive results, malignancy will exist often enough to warrant follow-up.

Relationships between bone structure in the iliac crest and bone structure and strength in the lumbar spine.

The purpose of this study was to examine the relationship between histomorphometric variables of cancellous bone structure and ultimate compressive strength (UCS) in the second lumbar vertebra (L2) and to determine whether structural variables in the iliac crest are predictive of the same variables and of UCS in L2. At autopsy, 7.5 mm diameter cores were removed from the iliac crest and from L2 of 29 subjects who had died suddenly without bone disease. Cancellous bone volume (BV/TV, %) was significantly lower in L2 than in iliac crest due to lower trabecular number (Tb.N, per mm) and thickness (Tb.Th, microns). There were significant correlations between iliac crest and L2 for BV/TV, Tb.N and trabecular separation (Tb.Sp, microns), but not for Tb.Th. BV/TV was negatively correlated, and Tb.Sp was positively correlated with age at both sites. Tb.Th was not significantly correlated with age in the iliac crest, but a significant negative correlation was observed in L2. The UCS of vertebral cores was negatively correlated with age. BV/TV and Tb.Th in L2 were positively correlated with UCS in L2.(ABSTRACT TRUNCATED AT 250 WORDS)