Validation of three-dimensional echocardiography for quantifying the extent of dyssynergy in canine acute myocardial infarction: comparison with two-dimensional echocardiography

OBJECTIVES

This study was designed to compare the accuracy of three- and two-dimensional echocardiography for quantifying the extent of abnormal wall motion in experimental acute myocardial infarction, as correlated with the pathologic determination of infarct size.

BACKGROUND

Two-dimensional echocardiographic estimations of the fraction of myocardium showing abnormal wall motion are often used as an index of infarct size even though they rely on image plane positioning and geometric assumptions that may not be valid. Three-dimensional echocardiographic reconstruction of the endocardial surface eliminates the need for these assumptions and may improve echocardiographic estimates of infarct size.

METHODS

Coronary ligation was performed in 14 open chest dogs, and echocardiographic imaging of the ventricle was performed 6 h later. Three-dimensional echocardiography used seven or eight spatially registered short-axis images to measure percent of endocardial surface and mass showing abnormal wall motion. Three two-dimensional echocardiographic methods using multiple, nonpatially registered images were evaluated. One method used seven or eight-axis slices and a summation of discs algorithm for computing surface area. The second method used the same images and a conical model for the left ventricle. The third used basal, middle and apical short-axis plus apical four- and two-chamber views comparing summed endocardial lengths showing abnormal wall motion with the total of the endocardial dimensions, expressed as percent. The percent of left ventricular mass and surface area infarcted was determined by staining with triphenyltetrazolium chloride.

RESULTS

Three-dimensional echocardiographic measurements of endocardial surface and correlated more closely with infarct mass (r = 0.94, SEE +/- 3.6%) than did the two-dimensional method using the summation of discs algorithm (r = 0.85, SEE +/- 6.6%), he summation of conical sections algorithm (r = 0.82, SEE +/- 5.4%) or the method using summed endocardial lengths (r = 0.79, SEE +/- 7.4%). Limits of agreement analysis comparing mass showing abnormal wall motion with anatomic infarct mass surface area showing abnormal wall motion with anatomic infarct surface area showed the smallest limits for three-dimensional echocardiography.

CONCLUSIONS

Three-dimensional echocardiography is a more accurate means of noninvasively estimating myocardial infarct size in this canine model than two-dimensional echocardiography.

Three-dimensional echocardiography compared to two-dimensional echocardiography for measurement of left ventricular mass anatomic validation in an open chest canine model

A three-dimensional echocardiographic system has been developed that can accurately compute left ventricular mass in vitro. This study was designed to validate the new echocardiographic system for the measurement of left ventricular mass in vivo and to compare the accuracy of three-dimensional echocardiography to the accuracy of conventional two-dimensional echocardiography for measuring left ventricular mass. Echocardiographic imaging was performed 6 h following coronary ligation in 20 open chest dogs, at which time the heart was excised and the left ventricle weighed. Three-dimensional echocardiography used multiple short axis sections and polyhedral surface reconstruction to compute myocardial volume. The two dimensional methods employed the truncated ellipsoid model and the area-length model. Myocardial volume was multiplied by 1.05 g/cc and echocardiographic mass estimates were compared to the true left ventricular weight. Three-dimensional echocardiography provided the best correlation (r = 0.96, upsilon r = 0.88 and r = 0.83 for the truncated-ellipsoid and area-length methods, respectively), and the lowest standard error of the estimate for the regression equation (+/- 5.5 g upsilon +/- 11.0 and +/- 14.6 g, respectively). Three dimensional echocardiography also had the lowest standard deviation for the echo-true mass differences (+/- 5.8 g upsilon +/- 10.7 g and +/- 14.2 g) and a lower root mean square percent error (6.8%) upsilon 12.6% and 12.7%). In this open chest canine model, three-dimensional echocardiography is more accurate than standard two-dimensional echocardiographic methods for measuring left ventricular mass.

Relation of Doppler transmitral flow patterns to functional status in congestive heart failure

We analyzed the relation of Doppler transmitral flow patterns and New York Heart Association (NYHA) classification in 60 consecutive patients with heart failure (44 men and 16 women; mean age 58 +/- 13 years) with left ventricular ejection fraction of < 40 percent. Of the study population, 40 patients with mild to moderate heart failure underwent symptom-limited exercise testing. The relation of transmitral flow pattern and exercise tolerance was also analyzed. Doppler echocardiography was performed in all patients. The patients were subdivided into nonrestrictive and restrictive groups according to the pattern. The univariate analysis showed a relation for left ventricular ejection fraction (p = 0.01 by analysis of variance testing) and transmitral flow pattern (p = 0.0003 by chi-squared test) with NYHA classification. When the multivariate regression analysis was performed, only the restrictive pattern by Doppler emerged as an independent determinant of the advanced NYHA class (p = 0.005). In mild to moderate congestive heart failure, patients with nonrestrictive pattern exercised significantly longer than those with the restrictive pattern by an average of 133 seconds (p = 0.003) despite comparable reductions in ejection fraction. Thus the restrictive transmitral flow pattern by Doppler is a noninvasive marker for severe symptoms and diminished exercise tolerance in heart failure patients.

In-vitro activity of carbapenem antibiotics against beta-lactam susceptible and resistant strains of Burkholderia pseudomallei

Four carbapenem antibiotics were tested for their in-vitro activities (MICs, MBCs and time-kill studies) against Burkholderia pseudomallei. The carbapenems were all more active than either ceftazidime or co-amoxiclav against strains of B. pseudomallei with a normal susceptibility pattern. Biapenem was the most active antibiotic tested. All four carbapenems retained bactericidal activity against 24 strains of B. pseudomallei with reduced susceptibility to ceftazidime and/or co-amoxiclav.

Evidence for dissociation of histone mRNA expression from cellular proliferation in cutaneous human papillomavirus infection

Replication of human papillomavirus (HPV) is thought to require the expression of components of the host cell DNA replication apparatus. The expression of the mRNA encoding the DNA replication-dependent histones H2B, H3, and H4 was investigated in a series of verrucae using an FITC-labelled oligonucleotide cocktail for in situ hybridization, to explore the possibility of HPV inducing the transcription of host cell histones. In contrast to normal epidermis, in which the majority of histone mRNA labelling was confined to basal cells, a bimodal distribution of histone positivity was observed in all verrucae. In addition to basal hyperproliferation-associated labelling, numerous positive suprabasal cells were found within the stratum spinosum. By contrast, in another hyperproliferative lesion, psoriasis, the labelling pattern was similar to that found in the normal controls, with characteristic basal hyperproliferation but no evidence of suprabasal labelling. The presence of HPV replication in every verruca and its absence from all controls of normal and psoriatic skin were demonstrated immunohistochemically, using a polyclonal antibody to the viral capsid proteins. It is proposed that the presence of histone mRNAs in differentiated suprabasal keratinocytes of verrucae is due to the virus turning on parts of the cellular apparatus in order for it to replicate in the absence of cellular proliferation. The results also emphasize that when assessing proliferation with in situ hybridization for histone mRNA, the possibility of HPV causing the labelling of non-proliferating cells should be considered.

Neutrophil trafficking into inflamed joints in patients with rheumatoid arthritis, and the effects of methylprednisolone

OBJECTIVE

To investigate the trafficking of circulating blood neutrophils and synovial fluid neutrophils in rheumatoid arthritis (RA) patients and the influence of a 1,000-mg intravenous pulse of methylprednisolone succinate (MP).

METHODS

Neutrophils were isolated from the circulation and from the knee synovial compartments of subjects with RA. Circulating neutrophils were labeled with technetium-99 hexametazime (99mTc-HMPAO) and reinjected intravenously. Synovial fluid neutrophils were labeled from indium-111 oxine and reinjected into the knee from which they were isolated. Gamma camera images were obtained at intervals up to 24 hours post MP. Each patient had a baseline study (no MP) and a study in which MP was administered either 4 hours before (2 patients), 10 minutes before (1 patient), or 30 minutes to 1.5 hours after (6 patients) injection of the radiolabeled neutrophils. Subsequent analysis allowed quantitation of the neutrophil uptake into and clearance from the knee as a function of time.

RESULTS

Nine patients who had not received glucocorticoids in the previous 3 months were studied. MP significantly decreased neutrophil ingress in 13 of the 16 knees studied (almost total inhibition in 5 knees), and this occurred within 1.5 hours of MP administration in all except 1 knee. At 24 hours after MP administration, there was a significant increase in visual analog scale (VAS) scores for well-being and significant decreases in scores on the modified Health Assessment Questionnaire (P<0.05), tender joints (P<0.005), VAS for pain (p<0.005), and generalized stiffness (P<0.005), as well as a decrease in the C-reactive protein level (P<0.05). MP had no effect on neutrophil egress (2 patients). Two additional patients who were receiving oral glucocorticoids were studied. One of them was clinically unresponsive to oral prednisolone, and MP had no effect on neutrophil ingress. The other patient showed no neutrophil ingress during the baseline study. This was confirmed by the presence of a noninflammatory synovial fluid at arthrocentesis.

CONCLUSION

Neutrophil ingress into and egress from inflamed joints can be accurately monitored using radiolabeled neutrophils and quantitative gamma camera imaging. MP rapidly and substantially decreases neutrophil ingress into inflamed joints. In contrast, MP has no effect on neutrophil egress from the joint.

A biomechanical study of torque and accuracy of halo pin insertional devices

The purpose of the present study was to assess the accuracy and repeatability of the torque achieved with a variety of devices used for the insertion of halo pins. We found that equivalent devices from the same manufacturer did not reliably achieve the same torque, that the same device used by different surgeons did not reliably achieve the same torque, and that the devices achieved varying levels of accuracy and repeatability. The proportion of trials in which the achieved torque was within +/- 10 per cent of the intended torque averaged 64 per cent (range, less than 1 to 100 per cent). Our data suggest that the insertion of halo pins with use of most currently available torque-setting devices is an inherently inaccurate process.

Cervical discogenic pain. Prospective correlation of magnetic resonance imaging and discography in asymptomatic subjects and pain sufferers

STUDY DESIGN

Asymptomatic subjects and chronic head/neck pain sufferers were studied with high-field magnetic resonance imaging and cervical discography to compare and correlate both tests.

OBJECTIVES

To assess the accuracy of magnetic resonance imaging and discography in identifying the source(s) of cervical discogenic pain.

SUMMARY OF BACKGROUND DATA

Previous retrospective studies describe a generally poor correlation between magnetic resonance imaging and provocative discography in the cervical spine.

METHODS

Ten lifelong asymptomatic subjects and 10 nonlitigious chronic neck/head pain patients underwent discography at C3-C4 through C6-C7 after magnetic resonance imaging. Disc morphology and provoked responses were recorded at each level studied.

RESULTS

Of 20 normal discs by magnetic resonance from the asymptomatic volunteers, 17 proved to have painless anular tears discographically. The average response per disc (N = 40) for this group was 2.42, compared to 5.2 (N = 40) for the neck pain group. In the pain patients, 11 discs appeared normal at magnetic resonance imaging, whereas 10 of these proved to have anular tears discographically. Two of these 10 proved concordantly painful with intensity ratings of at least 7/10. Discographically normal discs (N = 8) were never painful (both groups), whereas intensely painful discs all exhibited tears of both the inner and outer aspects of the anulus.

CONCLUSIONS

Significant cervical disc anular tears often escape magnetic resonance imaging detection, and magnetic resonance imaging cannot reliably identify the source(s) of cervical discogenic pain.

Pharmacoeconomic analysis of smoking-cessation interventions

A model for evaluating the costs and benefits of smoking-cessation interventions is proposed and published data on the subject are analyzed. Decision-tree analysis was used to determine the costs and benefits, from an employer's perspective, of several smoking-cessation options. The probability that a smoker would stop smoking was based on two published meta-analyses of smoking-cessation interventions and a national study of nicotine patch users who received a smoking-cessation consultation from a pharmacist. The costs were determined by telephone interviews and market research information. A sensitivity analysis of treatment costs was conducted to determine the optimal treatment from the standpoint of costs versus benefits. The smoking-cessation intervention from which an employer would receive the greatest net benefit is the nicotine patch with smoking-cessation consultation from a pharmacist and patient participation in a formal smoking-cessation program. Pharmacists included in this analysis could charge a smoking-cessation consultation fee of up to $109 per patient. Pharmacoeconomic analysis suggested that smoking-cessation therapy consisting of treatment with nicotine patches, consultations with pharmacists, and participation in a comprehensive behavioral program would be the most cost-beneficial to employers.

Techniques for measurement of oxygen consumption rates of hepatocytes during attachment and post-attachment

Three techniques for measuring oxygen consumption rate (OCR) of cultured cells relevant to the development of bioartificial liver devices are reported. In an oxystat apparatus, HepG2 cells immobilised on Cytodex 3 microcarriers at a concentration of 10(6) cells ml-1 had a mean OCR of 0.7 nmol s-1/10(6) cells. The OCR decreased with increasing cell density, a characteristic previously reported for other cell lines. Rat hepatocytes immobilised on single collagen layers in a flow cell and challenged with ammonia had a mean OCR of 0.59 nmol s-1/10(6) cells. A novel two-compartment oxystat system was used to determine the OCR of rat hepatocytes during the attachment phase. OCR declined from 1.0 nmol s-1/10(6) immediately after seeding to 0.7 nmol s-1/10(6) cells at nine hours. The low OCR for HepG2 reflects loss of certain oxygen dependent metabolic pathways. The OCR measured for rat hepatocytes during and post-attachment are significantly higher than those reported elsewhere and have major implications for the development of bioartificial liver devices.

Antibody production in plants

Production of heterologous proteins in plants has become increasingly efficient due to recent advances in plant biotechnology. Heterologous proteins that have specifically attracted a great deal of attention are plant-produced monoclonal antibodies. A variety of applications for these so-called plantibodies have been explored since they were first expressed in tobacco seven years ago. Both full length antibodies and antibody fragments produced in transgenic plants offer many intriguing possibilities to plant molecular biologists and plant breeders. However, questions such as how cellular targeting influences the expression and accumulation of these proteins in plants still need to be answered before the technology can be used commercially, on a large-scale.

Poly(vinyl chloride) formulations: acute toxicity to cultured human cell lines

Two quantitative cytotoxicity assay methods (cytoplasmic retention of carboxyfluorescein and mitochondrial cleavage of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT)) have been used to evaluate the response of two cultured human cell lines; HepG2 (hepatoma) and W138va13 (transformed lung fibroblasts) to extracts of a range of poly(vinyl chloride) (PVC) formulations. Two plasticizers; di(2-ethylhexyl)phthalate (DEHP) and di-isooctyl phthalate and a range of tin and non-tin stabilizers were incorporated in the study. Only those formulations containing both a plasticizer and a tin-based stabilizer produced extracts which were toxic. Extracts of those formulations which contained both plasticizer and dibutyl tin dimaleate stabilizer were toxic to both cell lines in both assay methods. Extracts of a formulation containing plasticizer and a dioctyl tin mercaptide were toxic to both cell lines in the carboxyfluorescein assay but were only toxic to the WI38va13 cells in the MTT assay. The WI38va13 cells were generally more sensitive to the extracts than the HepG2 cells. When serial dilutions of the extracts were evaluated, the carboxyfluorescein assay proved to be the more sensitive of the two. The acute toxicity of extracts of these PVC formulations cannot be directly attributed to the plasticizers or to the tin stabilizers. It is likely that a synergistic mechanism, such as plasticizer facilitated extraction of the tin stabilizer, exists.

Prognostic significance of quantitative bacteremia in septicemic melioidosis

Pour-plate blood cultures were performed for 418 adult patients with suspected septicemic melioidosis in order to determine the relationship between quantitative bacterial counts in blood and mortality. Of 108 patients whose hemocultures yielded Burkholderia pseudomallei, 53% had < 10 cfu/mL and 24% had > 100 cfu/mL. High blood bacterial counts were more common than reported previously with regard to other gram-negative septicemias and were significantly associated with the development of hypotension (P = .008) and a fatal outcome (P = .0001). The overall mortality was 63% (95% CI, 53%-72%); however, counts of < or = 1 cfu/mL were associated with a mortality of 42% (95% CI, 28%-58%), compared with 96% (95% CI, 80%-100%) with counts of > 100 cfu/mL. Heavy bacteremia (> 50 cfu/mL) is common in septicemic melioidosis and is usually fatal.

Enzyme-linked immunosorbent assay (ELISA) using a glycolipid antigen for the serodiagnosis of melioidosis

The serodiagnosis of melioidosis is commonly performed with tests using protein or polysaccharide as antigen. However, due to the low sensitivity, specificity and difficulty in the preparation of the antigens, more simple, precise and reproducible diagnostic tests were required. A purified glycolipid antigen (GL) which is a specific lipid component of Burkholderia pseudomallei has been used in an ELISA. With this antigen, specific immunoglobulin G (IgG) was detected in 49 out of 50 melioidosis sera. IgG was also detected in 2 out of 185 (Japanese) and 16 out of 181 (Vietnamese) control sera. Thus, the sensitivity was 98.0%, and specificity was 98.9% and 91.1% in the Japanese and Vietnamese sera, respectively. When the ELISA and indirect haemagglutination (IHA) tests were combined, a sensitivity of 100% and specificity of 97.8% were achieved. The advantages of the glycolipid antigen are ease of preparation, stability, high sensitivity and specificity.

Lysine residues at positions 234 and 236 in yeast porin are involved in its assembly into the mitochondrial outer membrane

Various point mutations of lysyl residues in yeast mitochondrial porin (283 residues) were tested for their ability to assemble in vitro into the outer membranes of intact yeast mitochondria. Assembly was evaluated by protection from proteinases. The extent of assembly of two of the mutants, K234E and K236E porins, was much less than for wild-type in either post-translational or co-translational assembly assays. Lysine to glutamate mutants at other positions and K234R porin assembled as well as wild-type, but K234Q porin was poorly inserted. When both Lys-234 and Lys-236 were mutated, K234R/K236R porin was inserted better than K234Q/K236Q porin, which was inserted better than K234E/K236E; however, none of these mutants assembled as well as wild-type porin. It was concluded that optimal assembly of yeast porin depended on the presence of positively charged residues at both positions 234 and 236 and a lysine at one of these positions. After undergoing the assembly reaction, mutants that were vulnerable to proteinase K (i.e. K234E, K234Q, and K236E porins) seemed to be incompletely digested and were, to varying degrees, resistant to extraction by Na2CO3 (pH 11.5). These experiments suggested that these mutants were incompletely inserted into the outer membrane. Both Lys-234 and Lys-236 are included in an internal pentapeptide, VKAKV, that is conserved in porins from protists, plants, and animals, and it is possible that, at least, the lysines in this tract are one of the signals for the membrane assembly of these proteins.

The assessment of left ventricular filling dynamics using an online automatic border detection algorithm: comparison with cineventriculography

An echocardiographic system has been developed that performs automatic endocardial border detection and instantaneously calculates and displays a waveform of left ventricular cavity area versus time. The purpose of this study was to compare measurements of left ventricular filling dynamics from automatic border detection echocardiography with similar measurements from cineventriculography. Thirty-three patients undergoing cardiac catheterization had automatic border detection echocardiography performed within 45 minutes of cineventriculography. Ten patients had normal catheterization findings and 23 had cardiac disease. The automatic border detection waveforms generated from two echocardiographic views were measured to determine the fraction of filling occurring during the early diastolic rapid filling phase and during the filling phase resulting from atrial contraction. Similar fractions were derived from curves generated from frame-by-frame measurements of cineangiographic volumes. Results were analyzed by correlating echocardiographic and cineventriculographic results, and by a limits of agreement analysis (limits of agreement were +/- 2 standard deviations of the mean difference between echocardiography and cineventriculography). There were significant correlations between echocardiography and cineventriculography for each of the parameters studied. The best results were obtained for the apical four-chamber view (rapid filling fraction r = 0.72, P < 0.0001, atrial filling fraction r = 0.56, P < 0.001). Differences in filling patterns between normal and abnormal patient groups detected by cineventriculography were also detected by automatic border detection echocardiography. However, broad limits of agreement were observed, that may limit the ability of the automatic border detection system to reliably predict cineventriculographic results in an individual patient. Automatic border detection echocardiography can provide information about left ventricular filling dynamics that is similar to that obtained from frame-by-frame analysis of cineventriculograms. However, the variability in the results may limit the application of the technique in individual patients.