Evaluation of breast tumors with color Doppler imaging: a comparison with image-directed Doppler ultrasound

Preclinical experience has shown that it is possible to maintain and expand hematopoietic cells in liquid culture systems by provision of optimal combinations of colony-stimulating factors (CSF). Ex vivo hematopoietic cell expansion (HCE) would be expected to reduce harvesting time and effort and could also decrease the infusion dose necessary for hematopoietic reconstitution after bone marrow transplantation. In addition, ex vivo expanded cells might be of value for therapeutic gene transfer. The central question in ex vivo HCE is whether the CSF combinations employed provide not only amplification of the late progenitor pools, but also maintenance or expansion of the stem cell compartment to ensure long term engraftment. Choice of CSF and experimental parameters in the culture system appear to be the most critical factors influencing the outcome of strategies for ex vivo HCE. Moreover, it is essential to define the goal of HCE and to adapt the experimental conditions to obtain the required cell populations. In future work, it remains to test the potential applicability of ex vivo expanded cells and to carefully monitor the possibility of the expansion of tumoral cells in ex vivo proliferation systems.     

Validation of Streamflow Measurements Made with Acoustic Doppler Current Profilers

The U.S. Geological Survey and other international agencies have collaborated to conduct laboratory and field validations of acoustic Doppler current profiler (ADCP) measurements of streamflow. Laboratory validations made in a large towing basin show that the mean differences between tow cart velocity and ADCP bottom-track and water-track velocities were ?0.51 and ?1.10%, respectively. Field validations of commercially available ADCPs were conducted by comparing streamflow measurements made with ADCPs to reference streamflow measurements obtained from concurrent mechanical current-meter measurements, stable rating curves, salt-dilution measurements, or acoustic velocity meters. Data from 1,032 transects, comprising 100 discharge measurements, were analyzed from 22 sites in the United States, Canada, Sweden, and The Netherlands. Results of these analyses show that broadband ADCP streamflow measurements are unbiased when compared to the reference discharges regardless of the water mode used for making the measurement. Measurement duration is more important than the number of transects for reducing the uncertainty of the ADCP streamflow measurement.     

Charcot-Marie-Tooth disease with intermediate motor nerve conduction velocities: characterization of 14 Cx32 mutations in 35 families

Charcot-Marie-Tooth disease can be inherited either autosomal dominantly or recessively or linked to the X chromosome. X-linked dominant Charcot-Marie-Tooth disease (CMTX) is a sensorimotor peripheral neuropathy in which males have usually more severe clinical symptoms and decreased nerve conduction velocities than do females. CMTX is usually associated with mutations in exon 2 of the connexin 32 (Cx32) gene. DNA from 35 unrelated CMT patients, without the 17p11.2 duplication, but with median nerve conduction between 30 and 40 m/s, were tested for the presence of Cx32 mutations. The entire coding sequence of the Cx32 gene was explored using a rapid nonradioactive technique to detect single-strand conformation polymorphisms (SSCP) on large PCR fragments. Thirteen abnormal SSCP profiles were detected and characterized by sequencing. In addition, systematic sequencing of the entire Cx32 coding region in the remaining index cases revealed another mutation that was not detected by SSCP. A total of 14 mutations were found, five of which were not previously reported. These results demonstrate the high frequency (40%) of mutations in the coding region of the Cx32 gene in CMT patients with intermediate MNCV, without 17p11.2 duplications. Most of these mutations (93%) can be detected by SSCP.     

Noninvasive determination of language lateralization by functional transcranial Doppler sonography: a comparison with the Wada test

E.coli bacteria, grown in anaerobic conditions, in the medium with glucose, lactose or maltose, upon transferring into a fresh medium with the same sugar acidify it and accumulate potassium ions with a fixed stoichiometry for the N,N'-dicyclohexylcarbodiimide-inhibited cation fluxes, which is equal to 2H+ of the cytoplasm per one K+ of the medium. Such an H(+)-K(+)-exchange is sensitive to osmotic shock. In the medium with lactose or maltose cation fluxes are less and the intracellular K+ activity at the moment of maximal accumulation is lower. The H(+)-K(+)-exchange with a variable stoichiometry of cation fluxes is lost in bacteria, grown in a medium with lactose or maltose.     

Left ventricular diastolic properties of hypertensive patients measured by pulsed tissue Doppler imaging

Examination of left ventricular (LV) diastolic dysfunction in hypertensive patients has been based on parameters obtained from the transmitral flow velocity during pulsed Doppler echocardiography. However, these parameters are affected by loading conditions. We evaluated LV diastolic function along the longitudinal and transverse axes by pulsed tissue Doppler imaging (TDI) in 50 hypertensive (HT) patients and 36 age-matched healthy volunteers (N). Transmitral flow velocity was recorded by pulsed Doppler echocardiography. LV posterior wall motion velocity along the longitudinal and transverse axes also was recorded by pulsed TDI. In both groups, peak early diastolic velocity of the LV posterior wall (Ew) along the transverse axis (N: 15.8+/-5.2 cm/s, HT: 12.2+/-4.4 cm/s) was higher than that along the longitudinal axis (N: 12.7+/-3.1 cm/s, HT: 9.5+/-3.3 cm/s). Peak atrial systolic velocity of the LV posterior wall (Aw) along the longitudinal axis (N: 9.1+/-1.8 cm/s, HT: 9.7 +/-2.6 cm/s) significantly exceeded that along the transverse axis (N: 8.0+/-2.2 cm/s, HT: 8.4+/-2.4 cm/s) in both groups. The Ews were lower and the Aws were higher along both axes in the patient group than in the control group. The time intervals from the aortic component of the second heart sound to the peak of the early diastolic wave (IIA-Ews) along both the transverse (N: 142+/-18 ms, HT: 154+/-19 ms) and longitudinal (N: 151 16 ms, HT: 162+/-20 ms) axes were longer in the patient group. In 29 patients, Ews along both axes correlated negatively (transverse: r = -0.80, P < .0001; longitudinal: r = -0.71, P < .0001) and IIA-Ews correlated positively (transverse: r = 0.81, P < .0001; longitudinal: r = 0.74, P < .001) with the time constant of the LV pressure decay during isovolumic diastole. The Aws along both axes in the 24 patients without pseudonormalization in transmitral flow velocity correlated positively (transverse: r = 0.60, P < .001; longitudinal: r = 0.74, P < .0001) with the LV end-diastolic pressure. In conclusion, LV relaxation and filling along the longitudinal and transverse axes were impaired in many patients with hypertension. Pulsed TDI was useful for evaluating LV diastolic dynamics in this disease.     

Comparison of myocardial velocities by tissue color Doppler imaging in normal subjects and in dilated cardiomyopathy

The authors studied 35 normal subjects (41 +/- 6 years) and 22 patients with idiopathic dilated cardiomyopathy 48 +/- 7 years; ejection fraction: 31 +/- 12%) in order to determine normal values of myocardial velocities and to demonstrate the sensitivity of Doppler tissue imaging in detecting a significant decrease in myocardial velocities in patients with abnormal left ventricular contractility. Interventricular septal and left ventricular posterior wall velocities were recorded by M mode long axis parasternal views. In normal subjects, a velocity gradient in the posterior wall was observed, higher in the endocardium than in epicardium, in systole (5.1 +/- 1.5 versus 2.8 +/- 1 cm/s, p < 0.01), and early diastole (13.7 +/- 3.5 versus 5.7 +/- 2 cm/s, p < 0.001) and late diastole at the time of atrial contraction (2.7 +/- 2.1 versus 1.8 +/- 1.7 cm/s, p < 0.01). Moreover, the velocities are higher in the posterior wall than in the interventricular septum throughout the cardiac cycle. Finally, the velocities are higher in early diastole than in systole, both in the interventricular septum and posterior wall. In the group of patients with idiopathic dilated cardiomyopathy, the intramyocardial velocities were lower than in normal subjects. In addition, the velocity gradient in the posterior wall was absent in 15 of the 22 patients. The authors conclude that Doppler tissue imaging provides new information in the analysis of myocardial function both in systole and diastole.     

Comparison of regional myocardial velocities assessed by quantitative 2-dimensional and M-mode color Doppler tissue imaging: influence of the signal-to-noise ratio of color Doppler myocardial images on velocity estimators of the Doppler tissue imaging system

M-mode color Doppler imaging of the myocardium affords a greater sampling rate and signal-to-noise (S/N) ratio than 2-dimensional (2D) imaging. In this study, we compared myocardial velocities assessed by 2D and M-mode Doppler tissue imaging (DTI) at the same site and evaluated the influence of the S/N ratio on velocity estimates of the currently used DTI systems. In patients with and without impaired regional left ventricular function, myocardial velocities assessed by 2D DTI were lower than those obtained with M-mode DTI. The difference between regional velocities derived from both imaging techniques was positively correlated with the extent of the "black zone," which could be considered as indirectly reflecting the S/N ratio for each frame. Thus in the clinical setting and on currently used echocardiographs, 2D DTI may provide underestimated regional myocardial velocities when compared with M-mode, mainly because of the influence of the lower sampling rate and S/N ratio on velocity estimators of the imaging system.     

Aortic compliance measured by non-invasive Doppler ultrasound: application of a personal computer based MkII system and its repeatability

A non-invasive pulse-wave-velocity Doppler ultrasound technique for the assessment of aortic compliance is described. A computational approach for correcting for the effect of non-chronic changes in blood pressure is considered and applied to compliance measurements performed on an age-select cohort of 70 normotensive, normal healthy volunteers. In order to permit the wider availability of the pulse-wave-velocity Doppler ultrasound technique, the authors have developed a MkII system based on a standard 80486/33 MHz IBM compatible WINDOWS based personal computer; real-time spectral analysis being achieved using a relatively inexpensive but fast analogue to digital signal processing card. An overview of the new apparatus is provided and verification work to compare the repeatability of the MkI and MkII systems is described. Medical disorders such as atherosclerosis, diabetes mellitus, familial hypercholesterolaemia, growth hormone deficiency, and Ehlers-Danlos and Marfan's syndromes have all been shown to affect arterial wall compliance. We suggest that the in vivo clinical measurement of blood pressure corrected aortic distensibility using the MkII system may be a useful, reproducible, non-invasive tool for assessing such patients' susceptibility to atheromatous arterial disease as well as for monitoring their response to therapeutic interventions. Measurements in the aorta may be especially pertinent since the natural history of fatty streaks there tends to parallel that in the coronary vasculature thereby potentially affording a convenient surrogate estimate of coronary heart disease.     

A comparison of breeding value predictors for longevity using a linear model and survival analysis

A comparison was made among breeding values of sires for longevity that were obtained by different methods: phenotypic averages of daughters using only uncensored records, BLUP using only uncensored records, survival analysis using only uncensored records, and survival analysis using both censored and uncensored records. Two data files were used: one contained data from small herds, and the other contained data from large herds. The results from both data files were similar. Different methods of predicting breeding values resulted in different rankings of sires. The results obtained using phenotypic averages were weakly correlated (< or = 0.46) with those results obtained using the other methods of prediction. The REML BLUP had strong correlations (< or = -0.91) with the survival analysis predictor if the same data were used, and correlations weakened (< or = -0.60) when censored records were included in the survival analysis. The correlations are negative because the linear method analyzed longevity, and survival analysis measured the risk of being culled, which has an antagonistic relationship with longevity. The results from REML BLUP and survival analysis methods differed mainly because of the different data that were used (uncensored only versus both censored and uncensored).     

Validity of linear regression in method comparison studies: is it limited by the statistical model or the quality of the analytical input data?

We compared the application of ordinary linear regression, Deming regression, standardized principal component analysis, and Passing-Bablok regression to real-life method comparison studies to investigate whether the statistical model of regression or the analytical input data have more influence on the validity of the regression estimates. We took measurements of serum potassium as an example for comparisons that cover a narrow data range and measurements of serum estradiol-17beta as an example for comparisons that cover a wide data range. We demonstrate that, in practice, it is not the statistical model but the quality of the analytical input data that is crucial for interpretation of method comparison studies. We show the usefulness of ordinary linear regression, in particular, because it gives a better estimate of the standard deviation of the residuals than the other procedures. The latter is important for distinguishing whether the observed spread across the regression line is caused by the analytical imprecision alone or whether sample-related effects also contribute. We further demonstrate the usefulness of linear correlation analysis as a first screening test for the validity of linear regression data. When ordinary linear regression (in combination with correlation analysis) gives poor estimates, we recommend investigating the analytical reason for the poor performance instead of assuming that other linear regression procedures add substantial value to the interpretation of the study. This investigation should address whether (a) the x and y data are linearly related; (b) the total analytical imprecision (s(a,tot)) is responsible for the poor correlation; (c) sample-related effects are present (standard deviation of the residuals > s(a,tot)); (d) the samples are adequately distributed over the investigated range; and (e) the number of samples used for the comparison is adequate.     

The accuracy of the frequency-volume chart: comparison of self-reported and measured volumes

Tracheobronchial foreign bodies can usually be extracted by skillful application of endoscopic techniques. The authors report on experience in the treatment of an infant in whom a plastic object was extracted by an open surgical approach. The authors discussed clinical presentation and treatment options in the treatment of this patient who had a plastic pencil top lodged in the lung. In highly selected cases, an open surgical procedure entails less risk than endoscopic extraction.     

Investigation of Two Elemental Error Sources in Boat-Mounted Acoustic Doppler Current Profiler Measurements by Large Eddy Simulations

Measurements of water discharge and flow velocities in riverine and tidal environments are commonly made with acoustic Doppler current profilers (ADCPs) mounted on a moving boat. This paper presents results of high-resolution Large Eddy simulations (LES) conducted to investigate two elemental error sources in ADCP measurements from a moving boat. One of these errors is due to the flow disturbance induced by the boat-mounted ADCP. The other error is due to the lack of flow homogeneity in horizontal layers assumed by the ADCP algorithm to compute orthogonal velocities from the measured radial velocities along the acoustic beams. The first error is investigated by comparing LES results for an undisturbed flow field with LES results for a flow field disturbed by a boat-mounted ADCP. The second error is investigated by comparing the velocities beneath the ADCP simulated by LES with virtual ADCP velocities, which are obtained by applying the ADCP algorithm to LES velocities data mined along the path of the acoustic beams of the virtual profiler. The distribution of the Reynolds stresses beneath the ADCP estimated with the ADCP algorithm from the virtual ADCP velocity data are also compared with those obtained from the LES solutions for both the undisturbed and ADCP-disturbed flows. Results show that the boat significantly disturbs the flow field and that the disturbed flow field is qualitatively different from the flow fields observed around an isolated ADCP (no boat).     

Diagnosis of carotid artery stenosis: comparison of oculoplethysmography and Doppler supraorbital examination

Both Doppler supraorbital examination (OSM) and oculoplethysmography (OPG) were administered to 101 patients (202 arteries) to document the presence or absence of hemodynamically significant lesions of the internal carotid artery prior to angiography. There was no significant difference between the OSM and OPG with respect to diagnostic sensitivity or specificity, incidence of false-negative or false-positive results, and overall diagnostic accuracy. The diagnostic accuracy for the OSM and the OPG were 94.2% and 91.6%, respectively. In 171/202 (84.6%) arteries, the OSM and OPG were in diagnostic agreement, and the overall diagnostic accuracy of the combined tests was 97%. However, when the OSM and OPG did not agree (31/202 arteries, 15.4%), the diagnostic accuracy of neither the OSM nor the OPG was acceptable. Although the best diagnostic accuracy was obtained using two means of noninvasive cerebrovascular testing, in those instances where only one test may be available, the OPG would appear to be the test of choice. In those laboratories in which high diagnostic accuracy is obtained with the OSM, the addition of OPG testing will increase the overall diagnostic accuracy to a very high level. The presence of a midcervical bruit was found to have a very poor correlation with the incidence of hemodynamically significant stenoses of the internal carotid artery. Although both the OSM and OPG have minimal value in patients with symptomatic cerebrovascular disease, these tests play a very important role in screening patients for asymptomatic carotid stenosis or atypical cerebrovascular symptoms.     

Refining a complex ZhS32-VI nickel alloy from silicon and phosphorus by unidirectional solidification of the melt at low solidification front velocities

The possibility of decreasing the silicon and phosphorus contents in a high-temperature ZhS32-VI nickel alloy by directional movement of solidification front at a velocity V = 6 mm/h has been studied. As a result, the contents of the impurities have decreased as compared to those in the starting alloy; the decrease in the silicon and phosphorus contents is from 2 to 4 and from 14 to 20 times, respectively. Thus, nonmetallic inclusions, in particular, those containing silicon and phosphorus, are moved to the top of the ingot.     

Mathematical modelling of wustite pellet reduction: grain model in comparison with USCM

A mathematical time-dependent and non-isothermal model has been carried out on the basis of the grain model to study the behaviour of a wustite pellet undergoing chemical reactions with reducing gases. The behaviour of wustite pellet reduction analysed by the grain model has been compared with unreacted shrinking core model (USCM). The results show, unlike the grain model, USCM cannot properly predict the impact of gas mixture parameters and pellet characteristics on the local reduction degree. The results also display that when the grain diameter, temperature and tortuosity increase, the diffusivity resistance in the pellet increases which causes more heterogeneous reduction. However, an increment in porosity causes gases to easily diffuse in the pellet and as a result a less heterogeneous reduction will occur.     

DNA damage by gliotoxin from Aspergillus fumigatus. An occupational and environmental propagule: adduct detection as measured by 32P DNA radiolabelling and two-dimensional thin-layer chromatography

Gliotoxin is produced by the fungus Aspergillus fumigatus. Aspergillus is widespread in the environment and this ubiquitous nature results in disease and co-carcinogenesis to be distributed world-wide. Gliotoxin contains an epipolythiodioxopiperazine (ETP) ring that is believed to be involved in redox reactions. The reactive oxygen species produced interact with DNA to form hydroxylated and other altered DNA products. To measure DNA adduct formation, we used 32P radiolabelling and, after enzymatic DNA digestion, separated adducts in two dimensions using thin-layer chromatography (2D-TLC), with ultimate autoradiography and densitometry. HeLa DNA was incubated with 0.1 mmol l-1 and 0.3 mmol l-1 of gliotoxin (and necessary redox agents) for 1 and 20 h. We found an increase in 6-hydro-5,6-dihydroxythymidine (thymine glycol) monophosphate [d(TG)MP] from 0.0% to 30.4%, an increase in 8-hydroxy-2'-deoxyguanidine monophosphate [8(OH)dGMP] from 0.0% to 4.2%, an increase in deoxynucleotide diphosphate (dNDP) from zero adducts to six DNA adducts, as well as an increase of other as yet unidentified adducts. Also, time exposure may have a greater effect than concentration based on a 20-h incubation with 0.3 mmol l-1 gliotoxin that completely obliterates the pyrimidines deoxythymidine 3'-monophosphate (dTMP) and deoxycytidine 3'-monophosphate (dCMP).