An evaluation of the completeness and accuracy of active tuberculosis reporting in the United States military.

SETTING: Despite the low incidence of tuberculosis (TB) in the United States military, there is uncertainty in the overall reporting and estimates of incidence. OBJECTIVE: To assess TB reporting in the active component US military. DESIGN: TB notification in the US military was compared with three other data sources: laboratory, hospitalization and pharmacy records. Sensitivity and positive predictive value were estimated for all data sources using a gold standard of either a reportable medical event (RME) reported as confirmed or a positive laboratory result for Mycobacterium tuberculosis. Uncorrected and capture-recapture (CR) methods were used to estimate underreporting and completeness of data sources. RESULTS: Completeness of reporting of pulmonary TB cases was estimated as 72.4% uncorrected or 58.3% with CR. Even after correction for possible underreporting, the incidence of active pulmonary TB was only 0.87 per 100,000 person-years between 2004 and 2006. CONCLUSION: The rate of active TB in the US military is low. Like civilian surveillance, US military RME surveillance may substantially underreport TB incidence rates. Expanding surveillance to include data sources such as hospitalizations and pharmacy records will increase the number of TB diagnoses at the cost of including many false-positives.

Evidence of intrinsic differences in the light scattering properties of tumorigenic and nontumorigenic cells.

BACKGROUND: The objective of this study was to determine whether there are intrinsic differences in the light scattering properties of tumorigenic and nontumorigenic cells from a multistep carcinogenesis model. METHODS: Wavelength-dependent and polarization-dependent light scattering properties of cell suspensions were measured. RESULTS: Statistically significant differences were found between the tumorigenic and nontumorigenic cells. CONCLUSIONS. Differences in the light scattering properties of tumorigenic and nontumorigenic cells are attributed to a change in the average size of the scattering centers on the order of a few ten of nanometers. This work is relevant to the development of noninvasive optical methods for cancer diagnosis.

Mechanisms of light scattering from biological cells relevant to noninvasive optical-tissue diagnostics.

We have studied the optical properties of mammalian cell suspensions to provide a mechanistic basis for interpreting the optical properties of tissues in vivo. Measurements of the wavelength dependence of the reduced scattering coefficient and measurements of the phase function demonstrated that there is a distribution of scatterer sizes. The volumes of the scatterers are equivalent to those of spheres with diameters in the range between ~0.4 and 2.0 mum. Measurements of isolated organelles indicate that mitochondria and other similarly sized organelles are responsible for scattering at large angles, whereas nuclei are responsible for small-angle scattering. Therefore optical diagnostics are expected to be sensitive to organelle morphology but not directly to the size and shape of the cells.