Confirming Mycobacterium tuberculosis transmission from a cadaver to an embalmer using molecular epidemiology.

Genotyping results and epidemiologic investigation were used to confirm tuberculosis transmission from a cadaver to an embalmer. This investigation highlights the utility of genotyping in identifying unsuspected epidemiologic links and unusual transmission settings. In addition, the investigation provides additional evidence for the occupational risk of tuberculosis among funeral service workers and indicates a need for education about tuberculosis risk and the importance of adhering to appropriate infection control measures among funeral service workers.

Disparities in tuberculosis burden among South Asians living in New York City, 2001-2010.

OBJECTIVES: We have described the characteristics of South Asian-born tuberculosis (TB) patients living in New York City (NYC) and compared them with other foreign-born patients to explore possible explanations for the disproportionate burden of TB in the South Asian population. METHODS: We used data on demographic and clinical characteristics for TB patients identified by the NYC Bureau of Tuberculosis Control from 2001 to 2010 to compare South Asian patients with other Asian and other foreign-born patients. We reviewed genotyping and cluster investigation data for South Asian patients to assess the extent of genotype clustering and the possibility of local transmission in this population. RESULTS: The observed disparity in TB rates and burden among South Asians was not explained by social or clinical characteristics. A large amount of TB strain diversity was observed among South Asians, and they were less likely than other foreign-born patients to be infected with the same TB strain as another NYC patient. CONCLUSIONS: The majority of South Asians were likely infected with TB abroad. South Asians represent a meaningful foreign-born subpopulation for targeted detection and treatment of TB infection in NYC.

Reported cases of measles in international air travelers to the United States, August 2005-March 2008.

BACKGROUND: In countries with high rates of measles immunization, imported cases of measles represent an important continuing source of measles infection. METHODS: Airlines and state health departments report cases of suspected measles in international travelers to the Centers for Disease Control and Prevention Quarantine Stations. We reviewed these reports, maintained in an electronic database, to determine the demographic and epidemiologic characteristics of international air travelers infected with measles. RESULTS: We reviewed 35 confirmed cases of measles in air travelers and analyzed their demographic and epidemiologic characteristics. The median age of case travelers was 17 (range: 4 months-50 years). These travelers arrived from all regions of the world, including 10 countries with immunization rates of measles-containing vaccine below 90% and five others experiencing local outbreaks. Of 17 travelers for whom immunization status was known, 2 had been adequately immunized with at least two doses of a measles-virus containing vaccine, 9 were inadequately immunized, and an additional 6 infants had not been immunized because of age. CONCLUSIONS: Measles importations continue in the United States. Travelers should be aware of the importance of assuring up-to-date immunizations, especially when visiting countries experiencing a local measles outbreak. In addition, parents traveling with infants, and their physicians, should be aware of recommendations regarding the early administration of a dose of measles-containing vaccine for infants at least 6 months old traveling internationally.

Ultrasonic backscatter coefficients for weakly scattering, agar spheres in agar phantoms.

Applicability of ultrasound phantoms to biological tissue has been limited because most phantoms have generally used strong scatterers. The objective was to develop very weakly scattering phantoms, whose acoustic scattering properties are likely closer to those of tissues and then compare theoretical simulations and experimental backscatter coefficient (BSC) results. The phantoms consisted of agar spheres of various diameters (nominally between 90 and 212 microm), containing ultrafiltered milk, suspended in an agar background. BSC estimates were performed at two institutions over the frequency range 1-13 MHz, and compared to three models. Excellent agreement was shown between the two laboratory results as well as with the three models.

Interlaboratory comparison of backscatter coefficient estimates for tissue-mimicking phantoms.

Ultrasonic backscatter is useful for characterizing tissues and several groups have reported methods for estimating backscattering properties. Previous interlaboratory comparisons have been made to test the ability to accurately estimate the backscatter coefficient (BSC) by different laboratories around the world. Results of these comparisons showed variability in BSC estimates but were acquired only for a relatively narrow frequency range, and, most importantly, lacked reference to any independent predictions from scattering theory. The goal of this study was to compare Faran-scattering-theory predictions with cooperatively-measured backscatter coefficients for low-attenuating and tissue-like attenuating phantoms containing glass sphere scatterers of different sizes for which BSCs can independently be predicted. Ultrasonic backscatter measurementswere made for frequencies from 1 to 12 MHz. Backscatter coefficients were estimated using two different planar-reflector techniques at two laboratories for two groups of phantoms. Excellent agreement was observed between BSC estimates from both laboratories. In addition, good agreement with the predictions of Faran's theory was obtained, with average fractional (bias) errors ranging from 8-14%. This interlaboratory comparison demonstrates the ability to accurately estimate parameters derived from the BSC, including an effective scatterer size and the acoustic concentration, both of which may prove useful for diagnostic applications of ultrasound tissue characterization.

Cross-imaging platform comparison of ultrasonic backscatter coefficient measurements of live rat tumors.

OBJECTIVE: To translate quantitative ultrasound (QUS) from the laboratory into the clinic, it is necessary to demonstrate that the measurements are platform independent. Because the backscatter coefficient (BSC) is the fundamental estimate from which additional QUS estimates are calculated, agreement between BSC results using different systems must be demonstrated. This study was an intercomparison of BSCs from in vivo spontaneous rat mammary tumors acquired by different groups using 3 clinical array systems and a single-element laboratory scanner system. METHODS: Radio frequency data spanning the 1- to 14-MHz frequency range were acquired in 3 dimensions from all animals using each system. Each group processed their radio frequency data independently, and the resulting BSCs were compared. The rat tumors were diagnosed as either carcinoma or fibroadenoma. RESULTS: Carcinoma BSC results exhibited small variations between the multiple slices acquired with each transducer, with similar slopes of BSC versus frequency for all systems. Somewhat larger variations were observed in fibroadenomas, although BSC variations between slices of the same tumor were of comparable magnitude to variations between transducers and systems. The root mean squared (RMS) errors between different transducers and imaging platforms were highly variable. The lowest RMS errors were observed for the fibroadenomas between 4 and 5 MHz, with an average RMS error of 4 x 10(-5) cm(-1)Sr(-1) and an average BSC value of 7.1 x 10(-4) cm(-1)Sr(-1), or approximately 5% error. The highest errors were observed for the carcinoma between 7 and 8 MHz, with an RMS error of 1.1 x 10(-1) cm(-1)Sr(-1) and an average BSC value of 3.5 x 10(-2) cm(-1)Sr(-1), or approximately 300% error. CONCLUSIONS: This technical advance shows the potential for QUS technology to function with different imaging platforms.

Human respiratory mechanics demonstration model.

Respiratory mechanics is a difficult topic for instructors and students alike. Existing respiratory mechanics models are limited in their abilities to demonstrate any effects of rib cage movement on alveolar and intrapleural pressures. We developed a model that can be used in both large and small classroom settings. This model contains digital pressure displays and computer integration for real-time demonstration of pressure changes that correspond to the different phases of breathing. Moving the simulated diaphragm and rib cage causes a volume change that results in pressure changes visible on the digital sensors and computer display. Device testing confirmed the model's ability to accurately demonstrate pressure changes in proportion to physiological values. Classroom testing in 427 surveyed students showed improved understanding of respiratory concepts (P < 0.05). We conclude that our respiratory mechanics model is a valuable instructional tool and provide detailed instructions for those who would like to create their own.

Analysis by capillary electrophoresis of the kinetics of charge ladder formation for bovine carbonic anhydrase.

A series of charge ladders of bovine carbonic anhydrase II were synthesized and the relative abundances of the rungs analyzed by capillary electrophoresis as a function of the quantity of acylating agent used. A simulation that models the kinetics of formation of the members of the charge ladders is described. The observed rate constants decreased as the extent of acylation increased. These rate constants correlated adequately with theoretical rate constants calculated using Debye-Hückel theory. The data are compatible with, but do not demand, a model for the formation of this charge ladder in which all unacetylated amino groups in each rung have indistinguishable reactivity and in which the reactivity of the amines in each rung decreases as the net charge on the protein increases; in this model, decreased reactivity is due to increased extent of protonation. This agreement between experiment and model suggests that the charge shielding that results from an ionic strength of 130 mM is not sufficient to suppress the influence of the increasingly negative charge of the protein with acetylation on the extent of protonation of Lys epsilon-NH2 groups.

Prototyping of microfluidic devices in poly(dimethylsiloxane) using solid-object printing.

A solid-object printer was used to produce masters for the fabrication of microfluidic devices in poly(dimethylsiloxane) (PDMS). The printer provides an alternative to photolithography for applications where features of > 250 microm are needed. Solid-object printing is capable of delivering objects that have dimensions as large as 250 x 190 x 200 mm (x, y, z) with feature sizes that can range from 10 cm to 250 microm. The user designs a device in 3-D in a CAD program, and the CAD file is used by the printer to fabricate a master directly without the need for a mask. The printer can produce complex structures, including multilevel features, in one unattended printing. The masters are robust and inexpensive and can be fabricated rapidly. Once a master was obtained, a PDMS replica was fabricated by molding against it and used to fabricate a microfluidic device. The capabilities of this method are demonstrated by fabricating devices that contain multilevel and tall features, devices that cover a large area (approximately 150 cm2), and devices that contain nonintersecting, crossing channels.