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PubMed1993

Spontaneous activity, conduction velocity and segmental origin of different classes of thoracic preganglionic neurons projecting into the cat cervical sympathetic trunk.

Previously, in the anesthetized cat, thoracic preganglionic neurons projecting to the superior cervical ganglion were divided into four classes (groups I-IV) by way of their reflex pattern. Neurons of each class are probably involved in a distinct function, such as regulation of peripheral vascular resistance, regulation of blood flow through skin, regulation of pupil diameter, etc. Here it was tested whether the functionally different classes of thoracic preganglionic neurons also differ in the distribution of their segmental origin, their spontaneous activity and the conduction velocity of their axons. The segmental distribution of preganglionic neurons was almost identical to that determined previously with tracer methods. Distinct classes of neurons had different, although overlapping segmental distributions. Most group III neurons were located in segments T1 and T2, whereas group I, II and IV neurons showed a broader distribution. The subpopulations of preganglionic neurons did not differ in their rate of spontaneous activity. No significant difference was found in segmental distribution between neurons with spontaneous activity and silent neurons. No correlation was found between conduction velocity and spontaneous activity. The proportion of unmyelinated units was greater among group I (16.3%), group II (24.1%) and group IV (22.2%) neurons than among group III neurons (8%). The distributions of conduction velocity were significantly different between group I and group III and between group II and group III neurons. Axons of preganglionic neurons located in segments T1 and T2 conducted faster than axons of neurons located more caudally. The present study shows that distinct subpopulations of preganglionic neurons, as defined by their reflex patterns, differ in their segmental location within the spinal cord and with respect to the conduction velocity of their axons.

Animals↗
PubMed1987

Changes in the size of cells in the monocular segment of the primate lateral geniculate nucleus during normal development and following visual deprivation.

Cell areas have been measured in the monocular segment of the lateral geniculate nucleus in a series of 18 normal rhesus monkeys and in 27 following monocular or binocular lid closure or monocular enucleation. Cells in the parvocellular monocular segment shrank by 16% during the later period of normal development, between about 3 and 18 months of age, in contrasts to cells in the binocular segment which did not. Monocular closure at birth caused hypertrophy of cells in the undeprived monocular segment whereas long-term closure started later caused shrinkage of both deprived and undeprived parvocellular cells additional to that occurring during normal development. In both these instances cells in the monocular segment related to the undeprived eye are undergoing changes indicating some form of binocular interactions even in the monocular segment, but these interactions are considerably weaker than in the binocular part of the nucleus. Enucleation caused marked transneuronal degeneration of cells in the contralateral monocular segment of both infant and adult monkeys.

Animals↗
PubMed1988

The axon initial segment as a possible determinant of retinal ganglion cell dendritic geometry.

In wholemounted retinae of cat, rat and monkey, in which ganglion cells were retrogradely labelled with horseradish peroxidase, a quantitative analysis of the direction of the axon initial segment with respect to the optic disc and of the relationship between the axon initial segment and the direction and distribution of primary dendrites was performed on the class of largest ganglion cells. The results show the following. (1) In all 3 species, the majority of primary dendrites of ganglion cells are directed away from the axon initial segment. (2) Primary dendrites arise with a greater frequency from the region of the cell body opposite to the axon initial segment than close to it. (3) In cat the direction of the axon initial segments show less variance in their initial direction with respect to the optic disc than in rat or monkey. In adult cats the nucleus of alpha-ganglion cells occupies a central position. In the kitten the position of the nucleus is eccentric and lies in a part of the cell body opposite to the axon initial segment. The nucleus moves to a central position over the next 3 weeks. The position of the axon initial segment is discussed as a possible determinant of ganglion cell dendritic geometry.

Animals↗
PubMed1989

Changes in isovolumic segment shortening following acute coronary occlusion: disproportionate effects of anterior versus posterior ischemia.

We evaluated the changes in left ventricular pressure and isovolumic segment shortening in both the ischemic and nonischemic areas following acute coronary occlusion in 12 conscious dogs instrumented for the measurement of subendocardial segment lengths perfused by the left circumflex coronary artery and left anterior descending coronary artery, and left ventricular pressure. An externally inflatable pneumatic occluder was placed around the left circumflex coronary artery. In 6 dogs, another occluder was installed around the proximal left anterior descending coronary artery. Under the resting conditions, the isovolumic segment shortening in the areas supplied by the left anterior descending coronary artery and the left circumflex coronary artery were 2.1 +/- 0.5% (SE) and -0.1 +/- 0.5% (P less than 0.01; versus values in the area of the left anterior descending coronary artery), respectively. During a 1-min occlusion of the left circumflex coronary artery, the isovolumic shortening in the anterior segment increased to 3.8 +/- 0.5% (P less than 0.001; versus values in the basal state), while the posterior segment produced isovolumic elongation (-2.2 +/- 0.5%, P less than 0.001; versus values in the basal state). By contrast, during a 1-min occlusion of the left anterior descending coronary artery, the extent of isovolumic bulge in the anterior segment and the augmentation in the isovolumic shortening in the posterior segment was less prominent compared with the occlusion of the left circumflex coronary artery.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Value of analysis of the evolution of the pattern of the ST segment in exercise electrocardiograms.

We analysed retrospectively the exercise electrocardiogram records of all patients with positive exercise tests which, on subsequent coronary angiography, proved to be "false positives". The exercise records of 10 "false positive" patients were compared with the records of 10 patients with true positive tests in the setting of single vessel disease and 20 patients with true positive tests and multivessel disease. Patients proving to be false positives did not differ from those with true positive tests in respect to either the slope of the ST segment, the number and site of leads showing shift of the ST segment, or the peak exercise double product. The total duration of exercise, however, was significantly longer in patients having false positive tests (7.93 minutes SD 1.34) as compared to true positive results (5.95 minutes SD 1.9 in single vessel disease, and 4.4 minutes SD 2.2 in multivessel disease, P = less than 0.05). Eight of 10 patients having a false positive test showed an atypical evolution of the pattern of the ST segment. Seven had rapid normalization of depression of the ST segment immediately after cessation of exercise, while one showed shift of the ST segment only during the period of recovery. In contrast, 28 of 30 patients with true positive tests showed gradual normalization of the depressed ST segment during the period of recovery. We conclude that shifts in the ST segment that normalize rapidly on cessation of exercise are frequently a false positive finding.

Adult↗
PubMed1990

Topographic segmentation of waking EEG in medication-free schizophrenic patients.

Lehmann has demonstrated that EEG topography can be used to segment EEG map series into a sequence of spatially stationary segments characterized by location of potential maxima and minima. We employed topographic segmentation techniques to study 9 channel EEGs recorded from 11 medication-free schizophrenic patients and 10 normal controls during resting and active task conditions, retesting 8 patients after neuroleptic treatment. To define EEG segments, average reference potential maps corresponding to global field power peaks in theta, alpha, and low beta activity were classified according to locations of extreme minimum and maximum values. Normals and schizophrenics did not differ in the number or types of switches between segments, or the frequency of hemisphere crossing of potential extrema. However, EEGs of normal subjects were characterized by significantly more (P less than 0.003) unused theta segment types (of a theoretically possible 36). Moreover, medication significantly (P less than 0.02) increased the number of unused theta segment types in EEGs of schizophrenics. We interpret these findings as evidence of increased spatial variability of brain electrical activity in schizophrenics and discuss their functional implications.

Adult↗
PubMed1992

42-channel potential map series to visual contrast and stereo stimuli: perceptual and cognitive event-related segments.

Event-related potential maps to perceptual (stimulus type) and cognitive (stimulus relevance) manipulations were studied in 12 healthy volunteers using 42-channel mapping. Perceptual manipulation used three types of visual stimuli: rectangles constituted by: (1) contrast; (2) different densities of monocular Dynamic Random Dots (Flat DRD); and (3) different binocular disparities of Dynamic Random Dots (Stereo DRD). Cognitive manipulation within each stimulus type consisted of presenting the rectangles horizontally and vertically, one of the two with a probability of 33%, and requesting the subjects to count and thus attend to the 'rare' rectangles. Spatial characteristics of the maps were analyzed; this allowed conclusions about the generating sources. The map series were adaptively segmented using the minima points of the grand mean Global Field Power curve. Segment strength (Global Field Power) and segment landscape (locations of extreme potentials) were assessed. Stimulus type had effects from 78 to 310 ms, stimulus relevance was effective from 210 to 1000 ms. In the 78-174 ms segment, Stereo DRD and Flat DRD stimuli produced similar map landscapes, while contrast stimuli produced different map landscapes. Attended and ignored stimuli produced contrary effects on landscapes at 210-310 ms as compared to those at 310-546 ms, indicative of different neural populations activated by attention processes during these late event-related potential segments. Interaction between perceptual and cognitive manipulation occurred at 210-310 ms when perceiving stereo stimuli and attending to relevant monocular visible stimuli produced similar map landscapes, suggesting a common brain resource during this segment for automatic figure perception and voluntary attention. The observed functional differences of the segments contribute to the identification of global functional microstates of brain electric activity.

Adult↗
PubMed1993

Adaptive segmentation of spontaneous EEG map series into spatially defined microstates.

Space-oriented segmentation can decompose multi-channel EEG map series into time segments characterized by quasi-stationary field map configurations. This assesses the dynamics of the underlying processes as activities of different neural generator ensembles. Our method of space-oriented segmentation describes the scalp field at times of maximal field strength (Global Field Power) by the locations of the centroids of positive and negative map areas. A quantitative measure of the simultaneous distance of the centroid locations evaluates the similarity between consecutive maps. A segment is defined as a sequence of maps that do not differ from each other by more than a present value. Finally, the average centroid locations for each segment are entered into an agglomerative clustering procedure to obtain a set of distinct classes of field configurations. Four records of 16 s of 42-channel resting EEG (band-pass filtered 2-16 Hz) from six subjects were analyzed. Average segment duration was 157.9 ms. Most segments belonged to a small number of classes (from 2 to 6, mean 3.7 classes for 90% of analysis time). The most frequent class showed an anterior-posterior field orientation and covered from 45 to 74% (mean 55% across subjects) of total time, with an average duration of 265 ms. The procedure was also tested using temporally and spatially unstructured data (white noise and randomly shuffled EEG) to ascertain that the methods reflect the spatio-temporal structure of the EEG processes.

Adult↗
PubMed1989

The role of RNA segment 1 in an in vitro host restriction occurring in an avian influenza virus mutant.

A temperature sensitive mutant, ts C47, derived from A/FPV/Rostock/34 and with a ts mutation in RNA segment 8, fails to form plaques in MDCK cells. From data obtained with reassortant viruses using the human influenza isolate A/FM/1/47 it was apparent that more than one mutation contributed to the temperature-sensitive (ts) and host range (hr) phenotypes of ts C47, and the phenotype of reassortants containing RNA segment 1 from A/FM/1/47 indicated that this segment was involved. A single nucleotide substitution at nucleotide 1961, resulting in valine instead of methionine in the predicted amino acid sequence of polypeptide PB2, was found in RNA segment 1 of ts C47, but this mutation did not segregate with the attenuated phenotype on gene reassortment. The following conclusions are drawn: (a) that ts C47 has at least two mutations in addition to that already known to exist in RNA segment 8, one of which (that in RNA segment 1) does not contribute to the observed ts hr phenotypes and (b) that the hr phenotype can be suppressed by substitution of RNA segment 1 by that of another strain.

Amino Acid Sequence↗
PubMed1996

Coding sequences of both genome segments of a European 'very virulent' infectious bursal disease virus.

The sequences of segment A (encoding the VP2-VP4-VP3 polyprotein and VP5) and segment B (encoding VP1) of a recent, 'very virulent' (VV) European isolate (UK661) of infectious bursal disease virus (IBDV), a birnavirus, have been determined. There are 26 to 36 amino acid substitutions compared to any other type I IBDV within the segment A polyprotein (of these, 15 are unique) and about 50 substitutions within VP1 (of which 16 are unique). There is more variation compared to classical and antigenic variant viruses, of both virulent and attenuated phenotype, in VP1, VP3 and VP4 than in VP2, even though the latter has previously been identified as the most variable protein between different strains of type I IBDV. In VP3 and VP4, UK661 is the most diverged type I IBDV. Thus the origin of the virus is unclear. It is possible that strong functional constraints have preferentially maintained the primary structure of VP2, though the possibility of recombination cannot be excluded. There are no clear candidate mutations to account for the enhanced virulence of the VV IBDV. Polymerase motifs are well conserved in VP1 but there is an amino acid substitution next to the predicted active-site serine of the viral protease (VP4). In addition, there is a conservative substitution close to the postulated VP2-VP4 cleavage site. It is also now apparent that sequences of IBDV segment B (the segment encoding the RNA polymerase) do not group according to serotype (specified by the capsid proteins encoded on segment A), indicating that segment reassortment has occurred.

Amino Acid Sequence↗
PubMed1993

Segmentation of medical images through competitive learning.

In image analysis applications, segmentation of gray-level images into meaningful regions is an important low-level processing step. Various approaches to segmentation investigated in the literature, in general, use either local information of gray-level values of pixels (region growing based methods, for example) or the global information (histogram thresholding based methods, for example). Application of these approaches for segmenting medical images often does not provide satisfactory results. Medical images are usually characterized by low local contrast and noisy or faded features causing unacceptable performance of local information based segmentation methods. In addition, because of a large amount of structural information found in medical images, global information based segmentation methods yield inadequate results in region extraction. We present a novel approach to image segmentation that combines local contrast as well as global gray-level distribution information. The presented method adaptively learns useful features and regions through the use of a normalized contrast function as a measure of local information and a competitive learning based method to update region segmentation incorporating global information about the gray-level distribution of the image. In this paper, we present the framework of such a self organizing feature map, and show the results on simulated as well as real medical images.

Algorithms↗
PubMed1995

Release of prostaglandin E2 and leukotriene C4/D4 from airway segments isolated from rats after exposure to ozone for 20 months.

Metabolites of arachidonic acid have been implicated as mediators of some of the pulmonary effects observed after acute exposure to ozone. Accordingly, recent studies have focused on the effects of acute ozone exposure on the arachidonic acid cascade, however, whether eicosanoid metabolism is altered after chronic exposure to ozone is unknown. To begin to address this issue, we examined the effects of near-lifetime exposure to ozone on release of prostaglandin E2 (PGE2) and leukotriene C4/D4 from airway segments isolated from exposed Fischer-344 rats. Airway segments representing approximately eighth to tenth generation airways were isolated from rats of both genders that had been exposed for 6 h per day, 5 days per week for 20 months to filtered air or 0.12, 0.5 or 1.0 parts per million (ppm) ozone. Basal and stimulated release of eicosanoids were measured in the medium surrounding airway segments using enzymoimmunoassay. Basal release of PGE2 was detected in the medium surrounding airway segments and this release was unaffected by ozone exposure. Incubation of the segments with the calcium ionophore, A23187, increased the release of the prostaglandin; the A23187-induced release of PGE2 was significantly enhanced in airway segments isolated from rats in the 1.0 ppm exposure group. Basal release of leukotriene C4/D4 was not detected in the medium surrounding airway segments regardless of ozone exposure. Measurable amounts of the leukotriene were released during incubation with A23187, however, ozone was without affect on these levels. The results suggest that the cyclooxygenase pathway of the arachidonic acid cascade appears to be affected by ozone exposure. Which of the processes of prostaglandin production and release are affected by chronic ozone exposure remains to be determined.

Administration, Inhalation↗
PubMed1978

A thermoinducible lambda phage-ColE1 plasmid chimera for the overproduction of gene products from cloned DNA segments.

Two segments of lambda have been cloned into the multicopy plasmid pBR322. One extends from N through cII (NcII segment, from 71.3 to 81.0% on the physical map) and the other from N through P (NOP segment, from 71.3 to 86.5% on the physical map). Cells carrying these recombinant plasmids express lambda immunity (cIts) and Rex function. In addition, they decrease the efficiency of plating at 32 degrees C of lambdavir and lambdaimm434, but not that of lambdaimm21. Recombinant plasmids with lambdaNOP segments (pKC14, pKC16) differ from recombinant plasmid with labmdaNcII segment (pKC10) in two respects: (i) strains carrying pKC14 or pKC16 are killed at 42 degrees C, and (ii) these strains are thermally inducible for plasmid DNA synthesis, resulting in increase of plasmid copy number from an uninduced level of 50 to more than 130 per chromosome. It was suggested that both these differences are related to functions contained in the lambda DNA segment extending from 81.0 to 86.5%. The usefulness of plasmid pKC16 for overproduction of gene products from cloned DNA segments was demonstrated by cloning the E. coli exonuclease III gene (xth) in pKC16. Thermal induction of this xth plasmid (pSGr) results in a 125-fold increase in exonuclease III activity over that of a control strain lacking the xth gene insert. The extent of exonuclease III overproduction obtained by cloning xth gene in a lambda vector was similar to that obtained with pSGR3.

Coliphages↗
PubMed1992

The rate of decay of Rhodobacter capsulatus-specific puf mRNA segments is differentially affected by RNase E activity in Escherichia coli.

In Rhodobacter capsulatus the puf operon encodes proteins of the photosynthetic apparatus. The polycistronic puf mRNA is comprised of segments that show differential stability. Here, we show that the rate of decay of the 2.7-kb pufBALMX mRNA species in Escherichia coli depends on the activity of ribonuclease E (RNase E), whereas the degradation of the 0.5-kb pufBA mRNA segment is not affected by a mutation in the rne gene. The RNase E-promoted decay of the pufLMX mRNA depends on the presence of a 1.4-kb pufLM mRNA segment, in which rate-limiting endonucleolytic cleavage was postulated to occur in R. capsulatus. The insertion of 185 bp of this 1.4-kb segment into pufB results in an RNase E-dependent decay of the modified pufBA mRNA segment in E. coli. Our findings suggest that in R. capsulatus an RNase E-like activity is responsible for the rate-limiting endonucleolytic cleavage occurring within the pufLM mRNA segment, whereas the 0.5-kb pufBA mRNA segment is degraded by a different RNase E-independent decay mechanism.

Blotting, Northern↗
PubMed1990

Three-channel Lissajous' trajectories of auditory brainstem evoked potentials: contribution of fast and slow components to planar segment formation.

Three-Channel Lissajous' Trajectories (3CLT) of Auditory Brainstem Evoked Potentials (ABEP) to clicks were obtained after finite impulse response filtering in three frequency bands. These bands were chosen to replicate the widely used passband (100-3000 Hz) and to selectively enhance the definition of the 'pedestal' (10-240 Hz) or the first, third and fifth components (240-483 Hz). Quantitative measures of 3CLT were calculated to describe apex latencies, planar segment orientations, durations, trajectory amplitude peaks and their latencies. In addition, dipole moments at the latencies of apical points along 3-CLT were calculated. The planarity of ABEP 3-CLT segments persisted after selective enhancement of the 'pedestal' or the first, third and fifth components. These results rule out the suggestion that planarity of ABEP segments results from the interaction of the 'pedestal' with the superimposed faster components. These results demonstrate summation of 3-CLT planar segments ('a' 'c' and 'e' with the 'pedestal') to form new segments (wide-band 'a', 'c' and 'e'). With the exception of 'c', planar segments and the equivalent dipole moments associated with apexes did not change orientations across passbands. The effects of passband on the orientation of planar segment 'c' and the dipole moment of its apex are explained by its superimposition on the 'pedestal' in the wide-band records. A similar analysis of ABEP to clicks as compared to low-frequency stimuli (high-pass masked clicks) revealed no change in planarity nor in plane parameters. These results are compatible with the suggestion that the generators of the first, third and fifth ABEP components are curved fiber tracts. The planarity of the slow 'pedestal' may be due to the summation of slow synaptic potentials in auditory brainstem nuclei. These findings indicate that the generators of ABEP are composites that may be separated by selective lesion studies.

Acoustic Stimulation↗
PubMed1989

Right coronary artery occlusion: its role in the mechanism of precordial ST segment depression.

To investigate the mechanism of precordial ST segment depression during right coronary artery occlusion, precordial ST segment shifts and myocardial lactate metabolism were evaluated during coronary angioplasty in 10 patients with (group A) and 7 patients without (group B) precordial ST segment depression during balloon occlusion of the right coronary artery, and in 17 patients with precordial ST segment depression during balloon occlusion of the left anterior descending artery (group C). A 12 lead electrocardiogram was continuously recorded in each patient. Blood lactate in the aorta and great cardiac vein was measured during the procedure, and the lactate extraction ratio in the anterior wall was determined both before and during balloon occlusion. Eight of the 10 patients in group A and 1 of the 7 patients in group B had a dominant large right coronary artery. There were no significant differences in summed ST segment elevation in leads II, III and a VF between group A (0.56 +/- 0.26 mV) and group B (0.46 +/- 0.19 mV) during balloon occlusion of the right coronary artery, and no significant differences in summed ST segment depression in leads V1 to V6 during balloon occlusion between group A (0.44 +/- 0.26 mV) and group C (0.38 +/- 0.14 mV). Lactate extraction ratio before balloon occlusion was similar among the three groups. Patients in group A had a higher lactate extraction ratio during (38 +/- 11%) compared with before (30 +/- 11%) (p less than 0.05) balloon occlusion despite precordial ST segment depression.(ABSTRACT TRUNCATED AT 250 WORDS)

Angina Pectoris↗
PubMed1994

Validation of global and segmental left ventricular contractile function using gated planar technetium-99m sestamibi myocardial perfusion imaging.

OBJECTIVES: The purpose of this study was to test the hypothesis that segmental wall motion analysis determined from gated planar technetium-99m sestamibi myocardial imaging is reproducible and agrees well with echocardiographic data. BACKGROUND: Technetium-99m sestamibi is a new radiopharmaceutical recently approved for myocardial perfusion imaging. Its advantages include a dosimetry that allows use of a dose 10 to 15 times higher than that of thallium-201. As a result, myocardial counts are markedly improved and images can be collected in a gated mode to potentially allow assessment of global and segmental ventricular function. However, the reproducibility and accuracy of technetium-99m sestamibi imaging for measurement of global and segmental left ventricular function have not been evaluated or compared with those of a standard ventricular function technique, such as echocardiography. METHODS: We studied 136 patients referred for clinical technetium-99m sestamibi imaging. One-day rest-stress planar technetium-99m sestamibi protocols were used, gating the stress images. After technetium-99m sestamibi imaging, all patients had standard rest two-dimensional echocardiography. Global and segmental technetium-99m sestamibi and echocardiographic left ventricular contraction was graded qualitatively as normal or abnormal using a four-point grading system. RESULTS: Interobserver and intraobserver agreement was extremely high for global and segmental technetium-99m sestamibi wall motion analysis, with absolute agreements ranging from 0.92 to 1.00 and corresponding kappa values of 0.74 to 1.00 (p < 0.00001). Agreement with global and segmental echocardiographic wall motion was similarly very high, with absolute agreements ranging from 0.93 to 1.00 and corresponding kappa values of 0.75 to 1.00 (p < 0.00001). CONCLUSIONS: Gated technetium-99m sestamibi cardiac imaging provides information with regard to rest global and segmental left ventricular systolic function that is highly reproducible and agrees very well with results of two-dimensional echocardiography.

Adult↗
PubMed1995

ST segment and T wave characteristics as indicators of coronary heart disease risk: the Zutphen Study.

OBJECTIVES: This study evaluated the predictive value of T wave amplitude and ST segment level on lead I for angina pectoris, a first myocardial infarction, sudden death and coronary heart disease death in middle-aged and elderly men. BACKGROUND: Certain ST-T wave characteristics may reflect favorable autonomic cardiac control. Slight ST segment elevation has been reported to indicate a low risk of coronary heart disease mortality. METHODS: A total of 876 men, born between 1900 and 1920, participated in periodic medical examinations and were followed up with respect to morbidity and mortality from 1960 to 1985. In 1985, the remaining cohort was extended to 836 elderly men from the same birth cohort who were followed up until 1990. Relative risks in categories of T wave amplitude and ST segment level were estimated by survival analysis. RESULTS: Both middle-aged and elderly men with T wave amplitudes > or = 0.15 mV had a lower risk of myocardial infarction, coronary heart disease death and sudden death than men with T wave amplitudes 0.05 to 0.15 mV. The adjusted relative risk of coronary heart disease death was 0.5 (95% confidence interval [CI] 0.2 to 1.0); in men with T wave amplitude < or = 0.05 mV, relative risk was 2.0 (95% CI 1.3 to 3.1). Slight ST segment elevation was also associated with decreased risk: relative risk 0.5 (95% CI 0.3 to 1.0) compared with the isoelectric ST segment level. In men with ST segment depression, relative risk was 2.2 (95% CI 1.4 to 3.4). The association of T wave amplitude and ST segment level were independent of each other. CONCLUSIONS: In addition to the elevated risk of coronary heart disease that is associated with ST-T wave abnormalities, we observed that normal variations in repolarization characteristics are predictive of future heart disease.

Aged↗