The electrocardiographic exercise test in a population with reduced workup bias: diagnostic performance, computerized interpretation, and multivariable prediction. Veterans Affairs Cooperative Study in Health Services #016 (QUEXTA) Study Group. Quantitative Exercise Testing and Angiography

BACKGROUND

Empirical scores, computerized ST-segment measurements, and equations have been proposed as tools for improving the diagnostic performance of the exercise test.

OBJECTIVE

To compare the diagnostic utility of these scores, measurements, and equations with that of visual ST-segment measurements in patients with reduced workup bias.

DESIGN

Prospective analysis.

SETTING

12 university-affiliated Veterans Affairs Medical Centers.

PATIENTS

814 consecutive patients who presented with angina pectoris and agreed to undergo both exercise testing and coronary angiography.

MEASUREMENTS

Digital electrocardiographic recorders and angiographic calipers were used for testing at each site, and test results were sent to core laboratories.

RESULTS

Although 25% of patients had previously had testing, workup bias was reduced, as shown by comparison with a pilot study group. This reduction resulted in a sensitivity of 45% and a specificity of 85% for visual analysis. Computerized measurements and visual analysis had similar diagnostic power. Equations incorporating nonelectrocardiographic variables and either visual or computerized ST-segment measurement had similar discrimination and were superior to single ST-segment measurements. These equations correctly classified 5 more patients of every 100 tested (areas under the receiver-operating characteristic curve, 0.80 for equations and 0.68 for visual analysis; P < 0.001) in this population with a 50% prevalence of disease.

CONCLUSIONS

Standard exercise tests had lower sensitivity but higher specificity in this population with reduced work-up bias than in previous studies. Computerized ST-segment measurements were similar to visual ST-segment measurements made by cardiologists. Considering more than ST-segment measurements can enhance the diagnostic power of the exercise test.

The management of implant-retained overdenture treatment with custom-made metallic attachment housing

A technique using a custom-made cast alloy attachment housing for an implant-retained overdenture prosthesis is presented. Common problems encountered in implant-tissue bar-retained overdentures are discussed. Details of the modified laboratory procedure are described. This technique provides the clinician with an alternative for predictably treating patients with implant-retained overdentures.

Vacuum-formed matrix as a guide for the fabrication of craniofacial implant tissue bar-retained auricular prostheses

Craniofacial implant-retained auricular prostheses usually require a tissue bar and/or retentive elements in addition to the prosthetic ear. Complete coverage of the tissue bar and retentive elements in a given bulk of prosthetic material is sometimes difficult to achieve, but it is crucial to ensure that all the prosthetic components are kept within the contour of the auricular prosthesis to maintain esthetics and form. This article describes a method for fabrication of auricular prostheses with all the elements predictably confined within the anatomic contour of the prostheses.

A comparison of three methods of measuring 99mTc-DTPA lung clearance and their repeatability

The lung clearance of technetium-99m diethylenetriamine penta-acetic acid (99mTc-DTPA) is a measure of respiratory epithelial permeability. Many factors may contribute to the wide range of normal values, including the method of correction for background activity. The aim of this study was to compare three methods of analysis, including their repeatability. 99mTc-DTPA lung clearance imaging was performed on eight nonsmokers (age 32+/-2 yrs, forced expiratory volume in one second (FEV1) 102.8+/-3.3% predicted yrs, mean+/-SEM and seven smokers (age 46+/-4 yrs, p<0.01, versus nonsmokers; FEV1 88.9+/-8.9%, p<0.05 versus nonsmokers) on two occasions each. The smokers were asked to refrain from smoking for 12 h. An uncorrected analysis was compared with two methods corrected for recirculating background activity using an intravenous correction and inter-renal and shoulder background regions of interest. The uncorrected method gave higher mean values for 50% lung clearance of 99mTc-DTPA (t50) values than the inter-renal (p<0.001) and shoulder (p<0.001) methods of correction in nonsmokers and the inter-renal method gave lower values than the shoulder-corrected method (p<0.05). In smokers there was no difference. There were no differences in mean t50 values obtained on two separate visits. There was no difference in the repeatability of the three methods of analysis. The three methods of analysis produced comparable results with no differences in repeatability.

Cognitive, neuroimaging, and pathological studies in a patient with Pick's disease

We conducted cognitive, imaging, and neuropathological studies on a patient with Pick's disease. The patient was impaired at interpreting sentences with complex grammatical constructions, differing significantly from control subjects and patients with Alzheimer's disease (AD). Evaluation of regional brain functioning at rest, with positron emission tomography, revealed reduced left frontal activity compared with control subjects and AD patients. Autopsy demonstrated the classic pathology of Pick's disease, including massive neuron loss and gliosis in the frontal and cingulate cortex as well as numerous tau-positive hippocampal Pick bodies. The abnormal tau proteins were phosphorylated at the same amino acid residues as AD paired helical filament tau (PHFtau), but they exhibited a unique migration profile on western blot. Our observations support the hypothesis that a distinct variety of hyperphosphorylated tau in Pick's disease compromises the long-term viability of selectively vulnerable populations of neurons in frontal cortices that contribute to sentence processing.

The effect of curdlan sulphate on development in vitro of Plasmodium falciparum

Sulphated glycoconjugates have been reported to inhibit malarial merozoite invasion and interfere with rosetting and adhesion. Curdlan sulphate, a sulphated glycoconjugate with a favourable toxicity profile, exhibits antimalarial activity in vitro. The aim of this study was to characterize the antimalarial activity of curdlan and investigate its effect on adhesion. The antimalarial activity of curdlan at different points in the intraerythrocytic developmental cycle was investigated using morphological observation and radiolabelled hypoxanthine uptake as indices of parasite growth. Effects on adhesion were investigated using a platelet model. Curdlan suphate had no effect on the ability of the parasite to develop through the intraerythrocytic cycle. Inhibition of invasion was dependent on the drug being present at the time of invasion. Curdlan did not interfere with the ability of the parasite to adhere to the C36 receptor in the platelet model. In conclusion, the low toxicity of curdlan and its marked anti-invasion activity on merozoites make curdlan a potential auxiliary treatment for severe malaria.

Language comprehension and regional cerebral defects in frontotemporal degeneration and Alzheimer's disease

We related profiles of language comprehension difficulty to patterns of reduced cerebral functioning obtained with high-resolution single photon emission computed tomography (SPECT) in patients with neurodegenerative conditions. We found different patterns of reduced relative cerebral perfusion in patients with frontotemporal degeneration (FD) and patients with Alzheimer's disease (AD). Cognitive assessments also showed different patterns of impaired comprehension in patients with FD and patients with AD. Grammatical comprehension difficulty in FD correlated with relative cerebral perfusion in left frontal and anterior temporal brain regions; impaired semantic processing in AD correlated with relative cerebral perfusion in inferior parietal and superior temporal regions of the left hemisphere. These findings are consistent with the hypothesis that a neural network distributed throughout the left hemisphere subserving different aspects of language comprehension, rather than a single brain region, is responsible for understanding language.

Immediate maxillofacial prosthodontic rehabilitation after radical mid-face tumor resection

Mid-facial surgical defects can adversely affect a patient's esthetics and psychological well-being. Fabrication of a definitive mid-facial prosthesis can be a time-consuming procedure. It is crucial to minimize the time between the tumor resection and initial prosthetic rehabilitation. This article describes a method for rapid fabrication of a transitional facial prosthesis for mid-facial defects.

Strains of glycopeptide-resistant Enterococcus faecium can alter their van genotypes during an outbreak

Two isolates of Enterococcus faecium with VanA glycopeptide resistance were isolated during a hospital outbreak of E. faecium with plasmid-mediated VanB resistance. Both were found to be identical to the VanB outbreak strain by pulsed-field gel electrophoresis. The genotype of this strain changed from vanB to vanA through an intermediate isolate that contained both the vanA and vanB gene clusters on distinct plasmids.

Constraints on the cerebral basis for semantic processing from neuroimaging studies of Alzheimer's disease

OBJECTIVE

Functional activation studies of semantic processing in healthy adults have yielded conflicting results. The purpose was to evaluate the relative role of the brain regions implicated in semantic processing with converging evidence from imaging studies of patients with impaired semantic processing.

METHODS

Semantic memory was assessed in patients with Alzheimer's disease using two measures, and these performance patterns were related to profiles of reduced cerebral functioning obtained with high resolution single photon emission computed tomography (SPECT). Patients with frontotemporal degeneration were similarly evaluated as a control group.

RESULTS

Reduced relative cerebral perfusion was seen in parietal and posterior temporal brain regions of patients with Alzheimer's disease but not patients with frontotemporal degeneration. Impairments on semantically guided category membership decision tasks were also seen in patients with Alzheimer's disease but not those with frontotemporal degeneration. Performance on the semantic measures correlated with relative cerebral perfusion in inferior parietal and superior temporal regions of the left hemisphere only in Alzheimer's disease. Relative perfusion was significantly lower in these regions in patients with Alzheimer's disease with semantic difficulty compared with patients with Alzheimer's disease with relatively preserved semantic processing.

CONCLUSION

These findings provide converging evidence to support the contribution of superior temporal and inferior parietal regions of the left hemisphere to semantic processing.

The adequacy of oxygenation in patients with hypoxic chronic obstructive pulmonary disease treated with long-term domiciliary oxygen

Survival in patients with hypoxic chronic obstructive pulmonary disease (COPD) is improved by long-term oxygen therapy (LTOT). Such patients are known to desaturate during activity and at night. The aim of this study was to assess the adequacy of oxygenation in patients with COPD receiving LTOT. Oxygen saturation (SaO2) was measured at home over 24 h in 20 patients with hypoxic COPD receiving LTOT. Eleven had arterial oxygen partial pressure values (PaO2) > or = 8 kPa (Group 1) and nine had PaO2 < 8 kPa (Group 2), at rest, breathing oxygen. There was no difference in SaO2 during the day and night when breathing oxygen. In Group 1, SaO2 was > 90% for 78 +/- 24% of the 24-h period. Four patients spent between 75 and 90%, and three spent < 75% of the 24-h period with SaO2 > 90%. In Group 2, SaO2 was < 90% for 69 +/- 27% of the 24-h period (P = 0.02). Two patients spent between 75 and 90%, and four spent < 75% of the 24-h period with SaO2 > 90%. Measurements of SaO2 over 24 h in patients with hypoxic COPD, while breathing oxygen, add further information to arterial blood gas sampling on the adequacy of oxygenation, and reveal inadequate oxygenation in many patients.

Incidence and detection of multi-drug-resistant enterococci in Dublin hospitals

In February 1994, an outbreak of vancomycin-resistant Enterococcus faecium (VREM) occurred in the oncology unit of a Dublin hospital. Between February and July 1994, VREM was isolated from 18 patients, one staff member and 14 environmental sites within the unit. The isolates also had high-level aminoglycoside and penicillin resistance. Three pulsed-field gel electrophoresis (PFGE) types were identified, two of them from multiple patients and environmental sites. Plasmid typing allowed subdivision of PFGE types. A retrospective study of enterococci isolated from blood cultures between January 1991 and January 1994 showed that, before the outbreak, fewer than 2% of isolates were vancomycin-resistant but that the incidence of high-level gentamicin resistance had increased from 17% to 60% and ampicillin resistance from 22% to 51%. Among clinically significant non-blood-culture enterococci isolated between September and December 1993, fewer than 1% were vancomycin-resistant, 13% were ampicillin-resistant and 44% highly gentamicin-resistant. None produced beta-lactamase. High-content gentamicin disks (120 micrograms) and low-content vancomycin disks (5 micrograms) allowed simple, reliable detection of resistant enterococci. MICs of vancomycin and teicoplanin determined by agar dilution and E-test agreed well, but values tended to be slightly lower by E-test.

Galileo's First Images of Jupiter and the Galilean Satellites

The first images of Jupiter, Io, Europa, and Ganymede from the Galileo spacecraft reveal new information about Jupiter's Great Red Spot (GRS) and the surfaces of the Galilean satellites. Features similar to clusters of thunderstorms were found in the GRS. Nearby wave structures suggest that the GRS may be a shallow atmospheric feature. Changes in surface color and plume distribution indicate differences in resurfacing processes near hot spots on Io. Patchy emissions were seen while Io was in eclipse by Jupiter. The outer margins of prominent linear markings (triple bands) on Europa are diffuse, suggesting that material has been vented from fractures. Numerous small circular craters indicate localized areas of relatively old surface. Pervasive brittle deformation of an ice layer appears to have formed grooves on Ganymede. Dark terrain unexpectedly shows distinctive albedo variations to the limit of resolution.

Systemic oxidative stress in asthma, COPD, and smokers

An imbalance between oxidants and antioxidants is proposed in smokers and in patients with airways diseases. We tested this hypothesis by measuring the Trolox equivalent antioxidant capacity (TEAC) of plasma and the levels of products of lipid peroxidation as indices of overall oxidative stress. The plasma TEAC was markedly reduced (0.66 +/- 0.07 mmol/L; mean +/- SEM; n = 11), with increased levels of lipid peroxidation products, in healthy chronic smokers as compared with healthy nonsmokers (1.31 +/- 0.10 mmol/L, n = 14, p < 0.001), an effect that was exaggerated in those who had smoked 1 h before the study. Plasma TEAC was also low in patients presenting with acute exacerbations of chronic obstructive pulmonary disease (COPD) (0.46 +/- 0.10 mmol/L, n = 20, p < 0.001) or asthma (0.61 +/- 0.05 mmol/L, n = 9, p < 0.01) with increases in plasma lipid peroxidation products. There was a negative correlation between superoxide anion release by stimulated neutrophils and plasma antioxidant capacity (r = -0.73, p < 0.001) in patients with acute exacerbations of COPD. The profound decrease in TEAC was associated with a decreased plasma protein sulfhydryl concentrations in acute exacerbations of COPD but not in smokers or in asthmatic subjects. Therefore smoking, acute exacerbations of COPD, and asthma are associated with a marked oxidant/antioxidant imbalance in the blood, associated with evidence of increased oxidative stress. The decreased antioxidant capacity in plasma may result from different mechanisms in these conditions.

Improving the diagnostic accuracy of MR in the detection of infraspinatus tendon injuries

PURPOSE

Our goal was to determine the accuracy of MRI in the diagnosis of infraspinatus tendon injury and more specifically to determine if the antero-posterior extent of a rotator cuff tear is predictive of infraspinatus tearing.

METHOD

The MR images of 41 shoulders with surgically proven supraspinatus tears at surgery were retrospectively reviewed. The following were assessed for each of the 41 studies: the number of oblique coronal images on which a tendon defect could be seen, the angle subtended by the tear on axial images (the rotator cuff "axial angle"), and the extent of signal abnormality on sagittal images.

RESULTS

The rotator cuff axial angle was 75.6 degrees in patients with infraspinatus tendon tears (ITTs) versus 40 degrees in those without ITTs, and this difference was significant (p < 0.001, t = 3.06). The mean number of oblique coronal images (obtained with a 4 mm slice and 1 mm gap) showing signal abnormality was 5.4 in the ITT group versus 2.9 in those without ITTs, and this difference was also significant (p < 0.001, t = 4.45). The mean sagittal extent of the tendon abnormality was 24.6 mm in the ITT group and 11.6 mm in those without ITTs, but the difference was not significant (p > 0.05, t = 1.1364).

CONCLUSION

The axial angle and the number of oblique coronal images in which signal abnormality was present were significantly related to a higher incidence of infraspinatus tears.

Mutations in the carboxy-terminal domain of TBP affect the synthesis of human immunodeficiency virus type 1 full-length and short transcripts similarly

The human immunodeficiency virus type 1 promoter generates two types of RNA molecules, full-length transcripts and short transcripts. Synthesis of the short transcripts depends on the inducer of short transcripts (IST), an element located downstream of the start site. In the presence of the viral activator Tat, the synthesis of full-length transcripts is up-regulated while that of short transcripts is down-regulated. Full-length and short transcripts are probably generated by different types of transcription complexes. The first is IST independent, capable of efficient elongation, and up-regulated by Tat. The second is IST dependent, incapable of efficient elongation, and down-regulated by Tat. We have used an in vivo assay to assess the role of TBP in human immunodeficiency virus type I transcription and to test the effect of mutations in TBP on synthesis of full-length and short transcripts. We find that TBP bound to the TATA box is required for the synthesis of short and full-length transcripts as well as for Tat activation and that both yeast TBP and the carboxy-terminal domain of human TBP can replace full-length human TBP for these processes. Mutations in TBP affect the synthesis of short and full-length transcripts as well as Tat activation similarly, and these effects correlate with the previously described effects of these mutations on binding of TBP to the TBP-associated factor TAFII250 in vitro. Together, these results suggest that if short and full-length transcripts are generated by variant transcription complexes, these complexes use TBP similarly, probably as part of the TFIID complex.