Anatomic accuracy of airway training manikins compared with humans.

Airway simulators, or training manikins, are frequently used in research studies for device development and training purposes. This study was designed to determine the anatomic accuracy of the most frequently used low-fidelity airway training manikins. Computerised tomography scans and ruler measurements were taken of the SynDaver® , Laerdal® and AirSim® manikins. These measurements were compared with human computerised tomography (CT) scans (n = 33) from patients at the University of Michigan Medical Center or previously published values. Manikin measurements were scored as a percentile among the distribution of the same measurements in the human population and 10 out of 27 manikin measurements (nine measurements each in three manikins) were outside of two standard deviations from the mean in the participants. All three manikins were visually identifiable as outliers when plotting the first two dimensions from multidimensional scaling. In particular, the airway space between the epiglottis and posterior pharyngeal wall, through which airway devices must pass, was too large in all three manikins. SynDaver, Laerdal and AirSim manikins do not have anatomically correct static dimensions in relation to humans and these inaccuracies may lead to imprecise airway device development, negatively affect training and cause over-confidence in users.

Quantifying Sarcopenia Reference Values Using Lumbar and Thoracic Muscle Areas in a Healthy Population.

BACKGROUND: Sarcopenia is defined as the loss of skeletal muscle mass and function associated with aging. Muscle mass can be reliably and accurately quantified using clinical CT scans but reference measurements are lacking, particularly in healthy US populations. METHODS: Two-phase CT scans from healthy kidney donors (age 18-40) at the University of Michigan between 1999-2010 were utilized. Muscle mass was quantified using two thoracic and two lumbar muscle cross-sectional area (CSA) measures. Indexed measurements were computed as area divided by height-squared. Paired analyses of non-contrast and contrast phases and different Hounsfield Unit (HU) ranges for muscle were conducted to determine their effect on CSA muscle measures. We report the means, standard deviations, and 2SD sarcopenia cutoffs from this population. RESULTS: Healthy population CSA (cm2) cutoffs for N=604 males/females respectively were: 34.7/20.9 (T12 Dorsal Muscle), 91.5/55.9 (T12 Skeletal Muscle), 141.7/91.2 (L3 Skeletal Muscle), 23.5/14.3 (L4 Total Psoas Area), and 23.4/14.3 (L4 Psoas Muscle Area). Height-indexed CSA (cm2/m2) cutoffs for males/females respectively were: 10.9/7.8 (T12 Dorsal Muscle), 28.7/20.6 (T12 Skeletal Muscle), 44.6/34.0 (L3 Skeletal Muscle), 7.5/5.2 (L4 Total Psoas Area), and 7.4/5.2 (L4 Psoas Muscle Area). We confirmed that a mask of -29 to 150 HU is optimal and shows no significant difference between contrast-enhanced and non-contrast CT scan CSA measurements. CONCLUSIONS: We quantified reference values for lumbar and thoracic muscle CSA measures in a healthy US population. We defined the effect of IV contrast and different HU ranges for muscle. Combined, these results facilitate the extraction of clinically valuable data from the large numbers of existing scans performed for medical indications.

Identification and characterization of a human proliferation-associated nucleolar antigen with a molecular weight of 120,000 expressed in early G1 phase.

Tumor nucleoli were treated with polyclonal antisera to normal human tissue nucleoli to block some determinants common to tumor and normal tissue nucleoli. Immunization of mice with these immune complexes resulted in the development of a monoclonal antibody (FB2) to a novel Mr 120,000 nucleolar proliferation-associated antigen. By indirect immunofluorescence, antibody FB2 produced bright nucleolar staining in a variety of malignant tumors, including cancers of the breast, liver, gastrointestinal tract, genitourinary tract, blood, lymph system, lung, and brain. Although specific nucleolar immunofluorescence was not detectable in most normal tissues, it was detectable in some proliferating nonmalignant tissues including spermatogonia of the testes, ductal regions of hypertrophied prostates, and phytohemagglutinin-stimulated lymphocytes. The Mr 120,000 antigen was not detectable in 48-h serum-deprived HeLa cells but was readily detectable (within 30 min) following serum refeeding. The Mr 120,000 antigen was not detected in retinoic acid-treated HL-60 cells following morphological differentiation but was detectable in 48-h phytohemagglutinin-treated lymphocytes. These studies suggest that the Mr 120,000 antigen is a proliferation-associated antigen which plays a role in the early G1 phase of the cell cycle.

Effect of differentiation on the expression of a nucleolar antigen with a molecular weight of 145,000 in HL-60 cells.

Mr 145,000 nucleolar protein antigen (p145) is associated with growing cells (R. L. Ochs et al., J. Cell Biol., 101: 211a, 1985) and has been found in a broad range of human cancers (J. W. Freeman et al., Cancer Res., 46: 3593-3598, 1986). In this study the presence of nucleolar antigen p145 was examined in the human promyelocytic tumor cell line HL-60 which was induced to differentiate by retinoic acid. Differentiation was monitored by morphological changes, [3H]thymidine accumulation, the ability of cells to reduce nitroblue tetrazolium, and cell number. The monoclonal antibody to nucleolar antigen p145 produced bright immunofluorescence in all cycling interphase HL-60 cells; during mitosis only diffuse staining was detected. Nucleolar antigen p145 in HL-60 cells was undetectable after 132 h of treatment with retinoic acid. The absence of nucleolar antigen p145 was associated with an 81% decline in thymidine accumulation and apparent inactivation of ribosomal and nonribosomal DNA transcription as observed by electron microscopy. The loss in expression of the antigen also correlated with increased nitroblue tetrazolium-positive cells, appearance of morphologically distinct myeloid cells, and termination of cell proliferation. These data indicate that the expression of nucleolar antigen p145 occurred in cycling HL-60 cells but not in terminally differentiated noncycling HL-60 cells.

Identification and partial characterization of a nucleolar antigen with a molecular weight of 145,000 found in a broad range of human cancers.

Previous studies in our laboratory have indicated the presence of nucleolar antigens in tumors which were not detected in normal tissues. Some of the polyclonal antisera produced in these studies were shown to identify a Mr, 145,000 nucleolar antigen on immunoblots of tumor nucleoli but not in normal human liver nucleoli. A monoclonal antibody to a Mr 145,000 nucleolar protein (p145) was produced by immunization of mice with a nucleolar extract of HeLa cells which is enriched with this antigen. The monoclonal antibody showed bright nucleolar immunofluorescence localization in a broad range of human tumors including cancers of the gastrointestinal tract, genitourinary tract, lung, liver, muscle, cartilage, and blood. The p145 nucleolar antigen was not detected in most normal human tissues or in benign tumors, with only weak nucleolar staining observed in spermatogonia of the testes and in ductal regions of some hypertrophied prostates. Nucleolar antigen p145 was extracted from HeLa cell nucleoli by homogenization in a 0.01 M Tris buffer containing 0.2% deoxycholate. On sucrose density gradient centrifugation, the antigen remained sedimented with the nucleolar ribonucleoprotein fraction. Nucleolar antigen p145 was released from ribonucleoproteins following treatment with 4 M guanidinium hydrochloride or RNase. Peptide mapping of nucleolar antigen p145 showed that it was distinct from other known nucleolar antigens. Although it remains to be determined if the p145 antigen plays a role in cell transformation, maintenance of the malignant phenotype, or in cell division, it may have value as a tumor marker or as a therapeutic target.

Masking of nontumorous antigens for development of human tumor nucleolar antibodies with improved specificity.

Nucleoli purified from HeLa cells were spread by homogenization in low ionic strength buffer and by chelation of divalent cations. The antigenic determinants of these tumor nucleoli that are shared by normal liver nucleoli were masked by addition of rabbit anti-liver nucleolar antisera to form immune complexes. New Zealand White rabbits were immunized with these antibody-nucleolar complexes. The resulting antisera produced nucleolar fluorescence in HeLa cells but not in normal human liver or human kidney cells. One- and two-dimensional immunoblots identified a major Mr 58,000/pl 5.8 antigen in HeLa cells, which was not detected on corresponding immunoblots of normal human liver nucleoli. This method offers an improved approach to selection of tumor-associated antigens.

Epitope distribution and immunochemical characterization of nucleolar phosphoprotein C23 using ten monoclonal antibodies.

Extractable nucleolar proteins from HeLa cells were used as a source of antigen to immunize mice for monoclonal antibody (MAb) production. Ten of the resulting MAbs shown to identify nucleolar phosphoprotein (110 kD/pI 5.5) were purified and used in immunochemical studies to further characterize protein C23. All ten MAbs showed nucleolar localization by indirect immunofluorescence; one antibody (FR2) also showed some nucleoplasmic localization that was attributed to a shared epitope between protein C23 and a 72 kD nuclear/nucleolar antigen. Reciprocal antibody cross blocking studies indicated that the ten MAbs identified nine distinct epitopes on protein C23. Interestingly, seven of the nine epitopes were shown by immunofluorescence and competitive ELISA studies to be species related. Immunostained patterns of exponentially growing HeLa cells suggest that protein C23 exists in vivo solely as a 110 kD peptide. However, protein C23 was subject to rapid degradation into a number of proteolytic fragments upon extraction or storage of isolated nucleoli. The failure to find protein C23 related peptides with molecular sizes less than 110 kD in exponentially growing cells and the lack of cytoplasmic localization of any of the ten MAbs suggests that protein C23 is not a prepro-protein processed in vivo to form ribosomal proteins as previously suggested (1).