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.

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.

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.

Electromyographic biofeedback to improve lower extremity function after stroke: a meta-analysis.

OBJECTIVE: To examine the efficacy of electromyographic (EMG) biofeedback compared with conventional physiotherapy for improving lower extremity function in stroke patients. DATA SOURCES: A literature search covering the years 1976 to 1995 in MEDLINE, CINAHL, and EXCERPTA MEDICA. STUDY SELECTION: Studies of adults after stroke, in which the treatment group received biofeedback alone or with conventional physical therapy and the control group received conventional physical therapy. Outcomes included functional measures related to the lower extremity. The study design criterion was that all must be randomized controlled trials. DATA EXTRACTION: Study quality was assessed independently by two observers-using eight criteria. Data for analysis were extracted by two observers to ensure accuracy. DATA SYNTHESIS: For outcomes that were analyzed in more than one study, meta-analyses were done. Seventy-nine studies were identified as potentially relevant and eight studies met the selection criteria. The mean effect sizes were: for ankle dorsiflexion muscle strength, 1.17 (95% CI, .50-1.85; p = .0006); for gait quality, .48 (95% CI, -.06-1.01; p = .08); for ankle range of motion, .07 (95% CI, -.42-0.57; p = .78); for ankle angle during gait, .52 (95% CI, -.18-1.21; p = .14); for stride length, .09 (95% CI, -.56-.73; p = .80); and for gait speed, .31 (95% CI, -.16-.78; p = .20). CONCLUSIONS: The results indicate that EMG biofeedback is superior to conventional therapy alone for improving ankle dorsiflexion muscle strength.

Macular pigment and the colour-specificity of visual evoked potentials.

A modified Moreland anomaloscope was used to examine two subjects, one with dense macular pigment, the other with relatively light pigmentation. Chromatic visual evoked potentials (VEPs) were elicited from these two subjects using coarse, isoluminant gratings of different sizes. Colour-specificity was verified by comparing chromatic onset VEPs (reflecting sustained activity) with chromatic reversal VEPs (reflecting mainly transient activity) and also by Fourier analysis (colour-specific responses are dominated by the fundamental, transient activity by the second harmonic). Achromatic (transient-type) intrusions, produced by large blue-green gratings could be related to the extent of subject-specific macular pigmentation.

Interference filter calibration for vision research.

The radiant flux (F) transmitted by bandpass interference filters of similar type is approximately proportional to the product of peak transmittance (tp) and half-height bandwidth (Wh). A study of 297 filters of varied design (1-, 2-, 3-cavity), the collections of six vision laboratories, showed that this relation was not accurate across all filters. However, a simple function, incorporating Wh and another bandwidth Wi at a lower transmittance t, predicts F with a precision that is ample (+/- 5%) for most psychophysical research. This function provides a rapid means of calibration. Bandwidth errors caused by 2- and 3-cavity filters are discussed as well as their luminous 'blocking' efficacy.

Effect of diabetes associated increases in lens optical density on colour discrimination in insulin dependent diabetes.

Optical density (OD) of the crystalline lens has been shown in non-diabetics to increase linearly with age over the first five decades and at an increased rate thereafter; in insulin dependent diabetic (IDDM) patients, lens OD increases with age and with duration of diabetes at a rate similar to that in non-diabetics over the age of 60 years. Recently, it has been established that colour discrimination is abnormal in a majority of young patients with uncomplicated IDDM and angiographically normal retinas. Colour discrimination loss was attributed to functional abnormalities in the retina or neural pathways; yet the possibility exists that increases in lens OD may account for part or all of the colour discrimination loss in IDDM. In the present study, colour discrimination was compared in aretinopathic IDDM patients and age-matched controls, and then in a group of aretinopathic IDDM patients individually matched to controls with respect to lens OD. Colour discrimination was significantly worse in diabetic patients than in age-matched controls, and was significantly worse when diabetic patients were compared with controls matched for OD. The magnitude of the difference in 100 hue error score between diabetic patients and OD matched controls was, however, considerably less than the difference between diabetic patients and age-matched controls. These data suggest that colour discrimination loss in aretinopathic IDDM patients cannot be explained solely on the basis of diabetes induced increases in lens OD, but must involve abnormalities of the retina or its neural connections.

Optimization of stimuli for trit-anomaloscopy.

Free-choice colour matches were made by 50 young normal trichromats on an anomaloscope. Six equations, of the kind 'blue' + 'green' = 'cyan' + 'yellow', were used in which the stimuli were defined by narrow-band well blocked interference filters. The stimuli were selected so that the instrument controls, which varied the quantities (blue/green), (cyan/yellow) and (cyan + yellow), were nearly independent controls for hue, saturation and brightness respectively. 'Yellow', 'green' and 'cyan' were fixed at 589, 499 and 480 nm, respectively, and the least interindividual variation in blue/green was found for 'blue' in the region 430-439 nm. This and a similar finding in the pilot study of Moreland and Young agree with expectations based on the density spectrum for macular pigment measured by Ruddock. Matches made by a few selected subjects, when the saturation control was locked at a position for the population mean, in the presence of large but typical saturation differences, were the same as when all three controls were used.

Temporal variations in anomaloscope equations.

Temporal variations in the value of blue/green derived from the equation: 'Blue' + 'Green' = 'Cyan' + 'Yellow', seem to be of two kinds. Those found in a cross-sectional study of 167 normal eyes in the age range 13--83 years could be attributed to progressive changes in lens absorbance. Individual cyclic variations in short-term (12 h) and long-term (11 months) longitudinal studies could not be attributed to the lens.

Further observations on the extramacular chromatic mechanisms.

Monochromatic targets presented at 30 degrees excentricity on orange, magenta and blue backgrouds are used. A small monochromatic light, 476 nm on orange, 551 nm on magenta and 621 nm on blue, is flashed at 3 cps-1 on the centre of the targets. The size of the targets is varied and their luminance adjusted using neutral filters until the flashing light is just not visible. This method allows the study of chromatic mechanism sensitivity and of retinal interactions (summation and inhibition). Some observations in normal as well as in pathological conditions are presented.

Acquired 'tritan' deficiencies in macular pathology.

14 patients with maculopathy (18 eyes affected, 10 eyes clinically normal) were examined using the HRR plates, the Farnsworth F2 (tritan) plate, the Farnsworth panel D15 test, the Nagel anomaloscope (model I) and on a 'blue-green' equation for 2 degrees and 11 degrees fields on the Moreland anomaloscope. The correlation of tritan-like responses to each test and the differences between the 2 degrees and 11 degrees equations are discussed.