A table-top PXI based low-field spectrometer for solution dynamic nuclear polarization.

We present the development of a portable dynamic nuclear polarization (DNP) instrument based on the PCI eXtensions for Instrumentation platform. The main purpose of the instrument is for study of 1 H polarization enhancements in solution through the Overhauser mechanism at low magnetic fields. A DNP probe set was constructed for use at 6.7 mT, using a modified Alderman-Grant resonator at 241 MHz for saturation of the electron transition. The solenoid for detection of the enhanced 1 H signal at 288 kHz was constructed with Litz wire. The largest observed 1 H enhancements (ε) at 6.7 mT for 14 N-CTPO radical in air saturated aqueous solution was ε~65. A concentration dependence of the enhancement is observed, with maximum ε at 5.5 mM. A low resonator efficiency for saturation of the electron paramagnetic resonance transition results in a decrease in ε for the 10.3 mM sample. At high incident powers (42 W) and long pump times, capacitor heating effects can also decrease the enhancement. The core unit and program described here could be easily adopted for multi-frequency DNP work, depending on available main magnets and selection of the "plug and play" arbitrary waveform generator, digitizer, and radiofrequency synthesizer PCI eXtensions for Instrumentatione cards.

Sustained reduction in tuberculosis incidence following a community-based participatory intervention.

BACKGROUND: Rates of latent tuberculosis infection (LTBI) and tuberculosis (TB) disease are elevated in the rural southeastern United States and among US- and foreign-born Black residents. To prevent TB and reduce TB transmission, community-based strategies are essential. OBJECTIVE: To describe a community-based participatory intervention for improving the detection and treatment of LTBI and TB and reducing TB incidence. DESIGN: In rural Florida, we carried out a community educational TB campaign from 1997 to 2000, including presentations at community events, a media campaign and working with local community groups to develop culturally appropriate prevention messages. The campaign was implemented concurrently with a population-based LTBI survey. RESULTS: The annual TB incidence rate in the intervention area decreased from 81 per 100 000 in 1994-1997, to 42/ 100 000 in 1998-2001, and to 25/100 000 in 2002-2005 (P = 0.001). This decrease was not observed in communities where the intervention was not implemented. There was no decrease in the TB incidence rate ratio between Blacks and non-Blacks in either region during the study period. CONCLUSIONS: We conclude that community participation in LTBI screening and TB education was associated with a substantial reduction in TB rates. Although the TB incidence rate ratio did not decrease between Blacks and non-Blacks, TB incidence fell in all racial groups.

Dual skin tests with Mycobacterium avium sensitin and PPD to detect misdiagnosis of latent tuberculosis infection.

BACKGROUND: A positive tuberculin skin test (TST) may indicate cross-reacting immunity to non-tuberculous mycobacteria (NTM) and not latent tuberculosis infection (LTBI). OBJECTIVES: To assess misclassification of LTBI, as assessed by skin testing with Mycobacterium avium sensitin (MaS), and to determine how this misclassification affects the analysis of risk factors for LTBI. METHODS: In a population-based survey, participants underwent skin testing with M. tuberculosis purified protein derivative (PPD) and MaS. A PPD-dominant skin test was a reaction that was ≥ 3 mm larger than the MaS reaction; a MaS-dominant skin test was a reaction that was ≥ 3 mm larger than the PPD reaction. RESULTS: Of 447 randomly selected persons, 135 (30%) had a positive PPD test. Of these, 21 (16%) were MaS- dominant, and were therefore attributable to NTM and misclassified as LTBI. PPD reactions of 5-14 mm were more likely to be misclassified than those ≥ 15 mm (OR = 5.0, 95%CI 1.9-13.2). Adjusting for misclassification had only a small impact on the analysis of risk factors for LTBI. CONCLUSIONS: A substantial number of individuals who are diagnosed with LTBI are actually sensitized to NTM. Using dual skin testing would reduce misdiagnosis and prevent unnecessary treatment.

The Macular Assessment Profile test - a new VDU-based technique for measuring the spatial distribution of the macular pigment, lens density and rapid flicker sensitivity.

The measurement of macular pigment optical density (MPOD) in the eye is often carried out using optical techniques based on heterochromatic flicker photometry (HFP). These require the use of two spectrally-narrow beams, one at the wavelength of maximum absorption of the macular pigment (MP) and the other in the long wavelength region of the visible spectrum where MP absorption is negligible. A new technique for the measurement of MPOD spatial profiles has been developed by overcoming the current shortcomings associated with the use of visual displays. The new Macular Assessment Profile (MAP) test makes use of a 'notch' filter and a photometric model to measure and compute the peak MPOD value. Two other useful parameters are also computed from the same measurements. These describe the subject's sensitivity to rapid flicker and the absorption of blue light by the lens. MPOD profiles, lens density, rapid flicker sensitivity, and red/green (RG) and yellow/blue (YB) colour thresholds were measured in 54 normal subjects aged 18-61 years. The results confirm previous findings on ageing effects and demonstrate the complete absence of correlation between MPOD and the subject's YB chromatic thresholds. In contrast, RG chromatic sensitivity improves with higher levels of MPOD.

Racial disparities in primary and reactivation tuberculosis in a rural community in the southeastern United States.

SETTING: A rural section of a county in central Florida. BACKGROUND: Racial disparities in tuberculosis disease (TB) are substantial in the United States. OBJECTIVE: To determine if TB was attributable to primary infection, reactivation or both. DESIGN: A population-based survey of latent tuberculosis infection (LTBI), a case-control analysis of TB, and a cluster analysis of TB isolates were performed between 1997 and 2001. RESULTS: Of 447 survey participants, 135 (30%) had LTBI. Black race was strongly associated with LTBI among US-born (OR 2.6, 95%CI 1.3-5.5) and foreign-born subjects (OR 4.3, 95%CI 2.2-8.4). Risk factors for TB included human immunodeficiency virus (HIV; OR 27.4, 95%CI 10.1-74.1), drug use (OR 4.6, 95%CI 1.7-12.4) and Black race (OR 3.4, 95%CI 1.2-9.6). The population risk of TB attributable to Black race was 64%, while that attributable to HIV was 46%. Cluster analysis showed 67% of TB cases were clustered, but Blacks were not at a significantly increased risk of having a clustered isolate (OR 2.1, 95%CI 0.12-36.0). CONCLUSION: Both reactivation TB and recent TB transmission were increased among Blacks in this community. Therefore, LTBI screening and intensive contact tracing, both followed by LTBI treatment, will be needed to reduce TB in Blacks.

Lambda exonuclease digestion of CGG trinucleotide repeats.

Fragile X syndrome and other trinucleotide diseases are characterized by an elongation of a repeating DNA triplet. The ensemble-averaged lambda exonuclease digestion rate of different substrates, including one with an elongated FMR1 gene containing 120 CGG repeats, was measured using absorption and fluorescence spectroscopy. By use of magnetic tweezers sequence-dependent digestion rates and pausing was measured for individual lambda exonucleases. Within the triplet repeats a lower average and narrower distribution of rates and a higher frequency of pausing was observed.

The fabrication of uniform cylindrical nanoshells and their use as spectrally tunable MRI contrast agents.

A new form of tunable magnetic resonance imaging agent based on precisely dimensioned cylindrical magnetic nanoshells is introduced. Using top-down prepatterned substrates, the nanoshells are fabricated by exploiting what is usually regarded as a detrimental processing side-effect, namely the redeposition of material back-sputtered during ion-milling. The well-resolved nuclear magnetic resonance peaks of the resulting nanostructures attest to the nanoscale fabrication control and the general feasibility of such sputter redeposition for fabrication of a variety of self-supporting, highly monodisperse nanoscale structures.

Macular pigment and color discrimination.

An earlier modeling study of the effect of changes in macular pigment optical density (MPOD) on a wide range of surface colors is re-examined. That study reported changes in local chromaticity variance and in color spacing, some of which were incompatible with tritan-like confusions in normals associated with high-simulated MPOD. This disagreement might have arisen through the use of the von Kries correction for adaptation. The analysis is repeated, using 1782 reflectance spectra of natural and man-made colors. These colors are segregated into an array of 25 equally populated cells in an analogue of the MacLeod-Boynton cone excitation diagram. Removing the von Kries correction restores compatibility with other experimental data. Differences between the results for normal and anomalous trichromats, noted in the earlier study, are confirmed. An analysis of local chromaticity variance across color space indicates the presence of systematic patterns. The earlier study also reported differences in results across observer types (for example, between normals and protanomals) and this is addressed here by utilizing fundamentals defined by a variable photopigment template. Chromaticities are computed for the same 1782 reflectance spectra for normals and for a set of protanomals (for whom the anomalous L pigment is shifted between the normal L and M spectral locations). Colors are segregated into an array of 100 cells in an analogue of the MacLeod-Boynton cone excitation diagram. Changes in chromaticity variance with MPOD for these cells are mapped for normals and protanomals. Variance along the L/(L + M) axis is sensitive to the number of cells used for segmentation. It also increases with MPOD for normal observers but this trend reverses as the wavelength of maximum sensitivity of the L cone shifts towards shorter wavelengths (protanomalous locations).

Chromatic VEP assessment of human macular pigment: comparison with minimum motion and minimum flicker profiles.

To assess the effects of macular pigment optical density (MPOD) on isoluminant stimuli and to quantify MPOD electrophysiologically, MPOD distribution profiles were obtained in normal subjects using minimum motion and minimum flicker photometry. Isoluminance of VEP stimuli was determined using minimum flicker and tritan confusion lines were determined using a minimum distinct border criterion. Onset-offset and reversal VEPs to isoluminant red/green, blue/green, and subject-specific tritan gratings of different diameters were recorded from the same 14 subjects tested psychophysically. VEPs were additionally recorded to annular gratings. Chromatic VEP selectivity was assessed by Fourier analysis and as an index; onset negativity/(onset negativity + onset positivity). Peak MPOD varied between 0.2-0.8. Chromatic onset VEPs to all isoluminant 3-deg fields were predominantly negative. Larger blue/green and tritan stimuli elicited VEPs with additional positive, achromatic components; for 9-deg gratings, peak MPOD showed negative correlation with the power of the VEP fundamental (r = -0.70) and with the selectivity index (r = -0.83). Annular gratings elicited chromatic-specific B/G VEPs but only when isoluminance was determined for the annulus. Chromatic selectivity loss in VEPs to large B/G or Tritan gratings can be used to estimate subject-specific MPOD. An important implication is that isoluminant Tritan stimuli with short-wavelength components must be restricted in size in order to optimize koniocellular selectivity.

A chip-scale atomic clock based on 87Rb with improved frequency stability.

We demonstrate a microfabricated atomic clock physics package based on coherent population trapping (CPT) on the D1 line of 87Rb atoms. The package occupies a volume of 12 mm3 and requires 195 mW of power to operate at an ambient temperature of 200 degrees C. Compared to a previous microfabricated clock exciting the D2 transition in Cs [1], this 87Rb clock shows significantly improved short- and long-term stability. The instability at short times is 4 x?10-11 / tau?/2 and the improvement over the Cs device is due mainly to an increase in resonance amplitude. At longer times (tau?> 50 s), the improvement results from the reduction of a slow drift to ?5 x 10-9 / day. The drift is most likely caused by a chemical reaction of nitrogen and barium inside the cell. When probing the atoms on the D1 line, spin-exchange collisions between Rb atoms and optical pumping appear to have increased importance compared to the D2 line.

Moreland match revisited.

An earlier analysis, which yielded an optimal pair of blue and green primaries (436 & 490 nm) for tritanomaloscopy, is reevaluated. That analysis minimized population variance in the mid-match points of color normals by taking into account, for a set of blue and green tritanopic metamers, the contributions of the lens and macular pigment variances and of matching range. The revision to the matching-range contribution takes into account the effect, neglected in the original analysis, of the varying angle between the blue-green primary mixture lines and the corresponding cyan test and yellow desaturant mixture lines. Use is made of new measurements of the macular pigment absorbance spectrum, a new estimate of the lens absorbance spectrum, the population variances of the lens and macular pigment, and of matching-range data for a current Moreland equation. Tritanopic metamers are derived from a revised set of cone fundamentals. The net effect of all of these revisions on the specification of optimal primaries is small (440 and 488 nm). However, larger changes are involved in the choice of test and desaturant wavelengths.

Macular pigment assessment by motion photometry.

A Moreland anomaloscope was modified to measure macular pigment optical density (MPOD) profiles by motion photometry. A grating (spatial frequency 0.38 c deg(-1)), whose alternate bars were filled, respectively, with 460 nm (maximum MP absorption) and 580 nm (zero MP absorption) lights, drifted steadily at 37 degrees s(-1). The subject adjusted the 580 nm radiance to minimise perceived motion (equiluminance between 460 and 580 nm). Five or more settings were made for two foveal fields (0.9 degrees and 2.2 degrees diameter) and 11 extrafoveal annular fields (0.8 degrees -7.5 degrees eccentricity). Twenty subjects made measurements for both eyes: some with replications. MPOD profiles varied in scale (0.18-0.75 for the 0.9 degrees foveal field) and in shape. A mean profile was derived. Foveal data were optimally aligned with annular data in that profile when plotted at 0.71 of the foveal field radius. Factors that limit precision were identified, such as fixation errors foveally and Troxler's effect parafoveally.

Investigation of cutaneous microvascular activity and flare response in patients with fibromyalgia syndrome.

OBJECTIVES: To assess microvascular activity in the skin of patients with fibromyalgia syndrome (FMS) as compared with normal controls. METHODS: Fifteen patients, who fulfilled the American College of Rheumatology criteria for FMS, and 15 age- and sex-matched healthy controls, were studied. The microvascular activity of the skin overlying the trapezius muscle was quantified using iontophoresis of acetylcholine as an endothelial-dependent vasodilator and sodium nitroprusside as an endothelial-independent vasodilator. We also studied the flare response by iontophoresing acetylcholine continuously for 10 min to stimulate a ring of nociceptor c-fibre endings in the skin. RESULTS: There was no significant difference in cutaneous vascular responses to short-duration iontophoresis of acetylcholine and sodium nitroprusside at the three different doses used. The area under the curve (AUC) (mean+/-s.e.m.) for acetylcholine baseline, 20, 40, and 80 s were 6+/-0.7, 23+/-6, 45+/-7 and 66+/-10 AU for patients and 11+/-4, 24+/-3, 49+/-7 and 62+/-12 AU for controls, respectively (P=0.2, 0.9, 0.7, 0.8, respectively). The corresponding figures for sodium nitroprusside were 5+/-1, 18+/-7, 51+/-14 and 68+/-14 AU for patients and 8+/-3, 13+/-2, 39+/-5 and 61+/-9 AU for controls, respectively (P=0.2, 0.5, 0.4, 0.7, respectively). There was also no significant difference in the flare response in patients with FMS as compared with control subjects (119+/-15 and 131+/-13 AU, respectively; P=0.57). CONCLUSION: There are no significant differences in cutaneous microvascular reactivity between patients with FMS and control subjects.

Design and implementation of a collaborative molecular graphics environment.

During the determination of macromolecular structures, scientists routinely use complex graphics software to display various representations of the molecule of interest. Once the structure determination is complete, coordinates are deposited in the Protein Data Bank (PDB), from where anyone with an Internet connection may download and view them or request them on CD-ROM. However, the currently available visualization software is such that causal users, whose expertise may not be in structure determination, often cannot obtain useful images of interesting molecules without expending considerable time and effort. Existing visualization software is generally very complex, requiring a high degree of familiarity to obtain the best results, or else it is too simplistic to provide users with the level of customizability needed to get the most out of the atomic coordinates. Few of the existing software packages have the capability for collaborative visualization via the Internet. These and other issuses are being addressed by the Molecular Interactive Collaborative Environment (MICE) project (http://mice.sdsc.edu/). The core of the MICE project is the MICE application, an interactive molecular structure viewer with built-in collaborative capabilities. MICE not only addresses the issues of usability and flexibility but also extends the role of traditional visualization tools by allowing multiple users to view, manipulate, and interact with a single representation of a macromolecular structure. MICE is written entirely in Java, using the Java3D extensions for rendering and manipulation of the three-dimensional scene, and the Common Object Request Broker Architecture (CORBA) communications suite to enable collaborative manipulation of that scene.

TNF-alpha and IL-1 beta are not essential to the inflammatory response in LPS-induced airway disease.

To determine the role of tumor necrosis factor (TNF)-alpha and interleukin (IL)-1 beta in the lower respiratory tract inflammatory response after inhalation of lipopolysaccharide (LPS), we conducted inhalation exposure studies in mice lacking expression of TNF-alpha and/or IL-1 receptor type 1 and in mice with functional blockade of these cytokines using adenoviral vector delivery of soluble receptors to one or both cytokines. Alterations in airway physiology were assessed by pulmonary function testing before and immediately after 4 h of LPS exposure, and the cellular inflammatory response was measured by whole lung lavage and assessment of inflammatory cytokine protein and mRNA expression. Airway resistance after LPS exposure was similarly increased in all groups of mice without evidence that blockade of either or both cytokines was protective from this response. Additionally, all groups of mice demonstrated significant increases in lung lavage fluid cellularity with a complete shift in the population of cells to a predominantly neutrophilic infiltrate as well as elevation in inflammatory cytokine protein and mRNA levels. There were no significant differences between the groups in measures of lung inflammation. These results indicate that TNF-alpha and IL-1 beta do not appear to have an essential role in mediating the physiological or inflammatory response to inhaled LPS.

Cementless femoral revision arthroplasty of the hip: minimum 5 years followup.

Durable fixation of the femoral component to the bone in femoral revision arthroplasty of the hip is the main ingredient to a successful reconstruction. Because of poor durability of cemented fixation in revision, in 1984, one author began to use cementless fixation with extensively porous-coated chrome cobalt stems. The current authors report the durability of that fixation technique in 137 hips (134 patients) followed up 5 to 16 years. With a mean followup of 9.3 years, 10 (7%) of the stems have been removed. Five (4%) were removed for fixation problems and five (4%) were removed for infection. Using the radiographic criteria of Engh et al, 83% of the stems achieved bony ingrowth. No late failure of fixation was observed. Canal-filling prostheses were more likely to have bone ingrowth as were stems placed in femurs with lesser degrees of bone stock deficiency. Significant thigh pain was seen in 7% of bone ingrown stems, 16% of stable fibrous fixated stems, and 75% of unstable stems. Significant thigh pain in bone ingrown stems was observed more commonly in osteoporotic femurs and bone stock deficient femurs. Severe stress shielding correlated with preoperative osteoporosis and larger diameter stems but has not caused failure. Excellent durability of this fixation technique is evident.

The John Charnley Award. Wear is a function of use, not time.

Polyethylene wear (linear penetration) in 37 hip replacements was assessed from digital images using a validated two-dimensional, edge detection-based computer algorithm. Patient activity was assessed with a pedometer, a step activity monitor and a simple visual analog scale. Joint use was related to wear at the 90% confidence level. Without three recognized outliers, wear was highly correlated to use. The visual analog scale activity rating was significantly related to wear for the 24 hip replacements with standard polyethylene. Univariate regression analysis indicated that male gender, height, weight (which were both highly correlated to male gender) and hip center of rotation were significantly correlated to wear. Multivariate regression analysis indicated that male gender, femoral off-set, and Hylamer were significantly correlated to wear. Based on the wear and activity data from the 24 hip replacements with standard polyethylene, the average volumetric wear rate per million cycles with a 70 kg patient weight was 30 mm3. This unique in vivo result can be considered a target wear rate for standard polyethylene in hip simulator studies.

An observer-blinded comparison of supervised and unsupervised aerobic exercise regimens in fibromyalgia.

OBJECTIVE: To compare a supervised 12-week aerobic exercise class with unsupervised home aerobic exercises in the treatment of patients with fibromyalgia. METHODS: This was a 48-week randomized single (observer) blind study in a teaching hospital rheumatology and physiotherapy department. The subjects were 74 patients who fulfilled the American College of Rheumatology criteria for fibromyalgia. Results and conclusions. A 12-week exercise class programme with home exercises demonstrated no benefit over a single physiotherapy session with home exercises in the treatment of pain in patients with fibromyalgia. Neither group (nor the groups combined) showed an improvement in pain compared with baseline. There was some significant benefit in psychological well-being in the exercise class group and perhaps a slowing of functional deterioration in this group.

Promoting and supporting breast-feeding.

The family physician can significantly influence a mother's decision to breast-feed. Prenatal support, hospital management and subsequent pediatric and maternal visits are all-important components of breast-feeding promotion. Prenatal encouragement increases breast-feeding rates and identifies potential problem areas. Hospital practices should focus on rooming-in, early and frequent breast-feeding, skilled support and avoidance of artificial nipples, pacifiers and formula. Infant follow-up should be two to four days postdischarge, with liberal use of referral and support groups, including lactation consultants and peer counselors.