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PubMed1989

Natural history of ST-segment potential distribution determined by body surface mapping in patients with acute inferior infarction.

The authors studied the natural history of the electrocardiographic ST-segment using body surface mapping in 123 patients with acute inferior infarction who were not treated with thrombolytic agents. In 91 patients they compared body surface ST-segment maps recorded at 7.9 +/- 5.4 hours after the onset of acute myocardial infarction with maps recorded at 32.6 +/- 21.6 hours after infarction. In 46% of the patients the ST-segment distribution map pattern was unchanged. Twenty-eight percent of the patients moved to a ST-segment distribution associated with low mortality, and 7% correlated with a normal ST-segment distribution. Patients who started in a group dominated by marked anterior ST-segment depression or who developed this pattern at the time of the late map had a 45% morbidity, compared to 13% for patients who never developed this pattern (p less than 0.005). In a second group of 61 patients they compared maps recorded at 15.0 +/- 15.8 hours after infarction and repeat maps 19.6 +/- 13.0 recorded months later. At follow-up mapping, 44% of the patients correlated with a normal ST-segment distribution, 38% of patients had a low-risk pattern map and in 7% the map pattern was dominated by anterior ST-segment potential depression. The latter patients had a higher morbidity than patients in the other groups, but this did not reach statistical significance. Four of seven patients in this last group had significant angina at the time of follow-up mapping, compared to 2 of 54 patients in the other two groups (p less than 0.001).

Aged↗
PubMed1993

Relationship of ST-segment elevation to eventual QRS loss in acute anterior wall myocardial infarction.

The position of electrocardiographic ST-segment elevation in acute myocardial infarction (MI) is related to the region of infarction, but the relationship between the initial ST-segment elevation and the eventual loss of QRS voltage remains uncertain. The authors examined body surface map data in 76 patients with acute anterior wall MI to clarify this relationship. The patients had no evidence of previous MI, no subsequent MI, and did not receive thrombolytic therapy or other acute interventions. Maps were recorded on admission to the hospital, every 24 hours during the hospital stay, and again at follow-up examinations 6-48 months after the index MI. The region of ST-segment elevation on the initial body surface map was compared to the region of developed voltage loss in the QRS complex as measured by the integral 0-30, 0-40, 0-80, and 30-80 ms body surface maps subsequently recorded 24 hours, 48 hours, and over 6 months after the initial body surface map. There was a relationship between the position of the ST-segment elevation and the loss of the QRS segment voltages, which was pronounced early after acute MI and diminished months after the MI. The region of ST-segment elevation in the initial body surface map predicts the QRS loss. In the integral QRS0-30 map versus the initial ST-segment map the mean correlation coefficient was -0.54 +/- 0.33 with a median value of -0.67. The integral QRS0-40 map and ST-segment map had a mean correlation coefficient of 0.60 +/- 0.29 and median of 0.66. The mean correlation coefficient is less for the integral QRS0-80 map and nonexistent in the integral QRS30-80 map. This method may be useful for monitoring acute interventions in acute MI.

Electrocardiography↗
PubMed1987

Assignment of simian rotavirus SA11 temperature-sensitive mutant groups A, C, F, and G to genome segments.

Crosses were performed between prototype temperature-sensitive (ts) mutants of simian rotavirus SA11 representing reassortment groups A, C, F, and G and ts mutants of rhesus rotavirus RRV that belonged to different reassortment groups. Wild-type (ts+) reassortant progeny were identified by plaque formation at nonpermissive temperature (39 degrees), picked, and grown to high titer. The ts+ phenotype of the resulting progeny clones was verified by titration at 39 degrees and 31 degrees. The electropherotypes of the ts+ clones were determined by electrophoresis, and parental origin of each genome segment was assigned by comparison of segment mobility to parental markers. Analysis of the parental origin of genome segments in the ts+ reassortants derived from SA11 ts X RRV ts crosses revealed the following map locations of the SA11 prototype ts mutants: tsA(778), segment 4; tsC(606), segment 1; tsF(2124), segment 2; and tsG(2130), segment 6. The assignment of tsA was made on the basis of genome segment segregation in two independent crosses with each of two independent RRV ts mutants. The assignment of tsC was made on the basis of segregation in only a single cross with an RRV ts mutant; however, a larger number of progeny clones were examined from this cross. The lesion of tsF was mapped with data from three independent crosses using two different RRV ts mutants. The assignment of tsG was made on the basis of segregation in three independent crosses, two with RRV ts mutants and one with Wa. The assignments of tsA, tsC, and tsF were confirmed in crosses between RRV ts mutants representing those reassortment groups, and SA11 ts mutants in other reassortment groups.

Chromosome Mapping↗
PubMed1988

Rift Valley fever virus M segment: cell-free transcription and translation of virus-complementary RNA.

A cell-free system has been used to study gene expression of the M segment RNA of the Phlebovirus Rift Valley fever virus (RVFV). RVFV sequence-containing plasmids were used to synthesize M segment mRNA-like transcripts. These transcripts were then translated in vitro in the absence or presence of microsomal membranes. Cell-free translation of a transcript which closely resembled authentic M segment mRNA (RNA-7) yielded a primary translation product of 133 kilodaltons (kDa), the size expected of a polypeptide encompassing the entire open reading frame (ORF) of the M segment. When translations were conducted in the presence of microsomal membranes, this primary protein was cotranslationally processed to yield the two viral glycoproteins, G1 and G2, as well as proteins of 78, 21, and 14 kDa. With one exception, these in vitro processed polypeptides comigrated with M segment-encoded proteins found in RVFV-infected cell lysates. A polypeptide corresponding to the in vitro 21-kDa protein was not detected in vivo. To investigate translational initiation and processing of the protein products of the M segment, additional transcripts were generated in which varying portions of the amino-terminal "preglycoprotein" region of the M segment ORF were deleted. Translation results indicated that the 78- and 21-kDa proteins were initiated from the first methionine codon of the ORF, and the 14-kDa polypeptide began from the second in-phase ATG. These products and a major portion of the preglycoprotein region sequence were not required for the proper synthesis and processing of the viral glycoproteins in vitro. In light of these results, possible expression strategies used by this Phlebovirus M segment RNA are discussed.

Bunyaviridae↗
PubMed1991

Bluetongue virus evolution: sequence analyses of the genomic S1 segments and major core protein VP7.

The S1 segments, encoding the group-specific antigen, VP7, from the five United States prototype BTV serotypes were cloned as full-length entities. The nucleotide and deduced amino acid sequences of segment S1 of BTV-2 were determined and compared with BTV-10, -11, -13, and -17, completing the sequencing of this cognate gene segment from all five US BTV serotypes. Each segment is 1156 bp long and contains an open reading frame encoding the 349-amino acid VP7 protein. Most (greater than 94%) of the amino acids of VP7 among the serotypes are conserved, including the location (position 255) of a single lysine residue. Secondary structure analyses of VP7 predict a putative eight-stranded beta-barrel between amino acid positions 150 and 250, a structure similar to that observed in ssRNA viruses. The S1 genes are flanked by conserved 5' and 3' noncoding regions. Stem-loop structures are predicted at the 3' end of each gene (nucleotide positions 1058-1097). The S1 segments of BTV-2, -10, -11, and -17 have greater than 93% of the nucleotides conserved, while less than 80% of their bases are identical with BTV-13. Analyses of nucleotide mismatches in each codon position of the VP7 open reading frame, transition frequencies, and evolutionary distances show that of the five, BTV-13 is the most distantly related and that BTV-10 and -17 are the most closely related serotypes. Evolutionary distance calculations of segment L2 from BTV-10, -11, and -17 concur with these observations. Comparison of this relationship with hybridization data of segment M3, which codes for VP5, suggests that BTV-17 has evolved by a combination of genetic drift and genomic reassortment. The data also indicate that the five US BTV serotypes are derived from two distinct gene pools. Evolution distances were used to estimate an evolution rate of 2.2 x 10(-3) nucleotide substitution/site/year for BTV segment S1. This rate is similar to the genes of retroviruses and implies an absence of RNA polymerase proofreading activity for dsRNA viruses.

Amino Acid Sequence↗
PubMed1989

The Drosophila patched gene encodes a putative membrane protein required for segmental patterning.

The patched (ptc) gene is one of several segment polarity genes required for correct patterning within every segment of Drosophila. The absence of ptc gene function causes a transformation of the fate of cells in the middle part of each segment so that they form pattern elements characteristic of cells positioned around the segment border. Analysis of the mutant phenotype demonstrates that both segment and parasegment borders are included in the duplicated pattern of ptc mutants. We have cloned the ptc gene and deduced that the product is a 1286 amino acid protein with at least seven putative transmembrane alpha helices. ptc RNA is expressed in embryos in broad stripes of segmental periodicity that later split into two stripes per segment primordium. The pattern of expression does not directly predict the transformation seen in ptc mutant embryos, suggesting that ptc participates in cell interactions that establish pattern within the segment.

Amino Acid Sequence↗
PubMed1996

Synthesis and blood compatibility evaluation of segmented polyurethanes based on cholesterol and phosphatidylcholine analogous moieties.

New segmented polyurethanes based on cholesterol and phosphatidylcholine analogous moieties were synthesized. The soft segments used in this study were the poly(butadiene), poly(isoprene) or hydrogenated poly(isoprene) glycols; the hard segments of these segmented polyurethanes were composed of 4,4'-methylenediphenyl diisocyanate, 2-[bis(2-hydroxyethyl)methylammonio]ethyl 5-cholesten-3 beta-yl phosphate and 1,4-butanediol. The blood compatibilities of synthesized segmented polyurethanes were evaluated by platelet-rich plasma contact studies and scanning electron microscopy observation using glass as the reference. The results show that the blood compatibilities of the synthesized segmented polyurethanes have great difference between the glass contact side and air exposed side for the same cast films. Generally, the hydrogenated poly(isoprene)-based segmented polyurethane is the best surface in terms of platelet adhesion, and the morphology of adhered platelets undergoes the lowest degree of variation among the segmented polyurethanes investigated in this study.

Biocompatible Materials↗
PubMed1986

The role of the VL- and VH-segments in the preferential reassociation of immunoglobulin subunits.

Competitive reassociation experiments, in which equimolar amounts of two different L-chains were allowed to compete for a limiting amount of H-chain, were performed to assess the role of the V kappa- and J kappa-segments on the ability of an L-chain to compete. Using H- and L-chains from the murine anti-phosphorylcholine (PC) myelomas, TEPC15, MOPC167 and MCPC603, and a series of V kappa 21 L-chains, it was found that the V kappa 21 L-chains competed uniformly better than the anti-PC L-chains, when the anti-PC H-chains were used, despite any differences in the J-segments of the competing L-chains. In addition, when the anti-PC L-chains, which all employ identical J kappa-segments but very diverse V kappa-segments, were in competition against each other, a hierarchy of competitive ability existed which was independent of whether the chains were autologous or heterologous and independent of antigen binding activity. Competitive reassociation experiments between the V kappa 21 and anti-PC L-chains were also performed using the heterologous anti-lysozyme monoclonal HyHEL-10 H-chain or the anti-galactan J539 H-chain, and it was found that the relative competitive ability of the V kappa 21 L-chains with respect to the anti-PC L-chains was dependent on which H-chain was employed. The results suggested that the main factor favouring preferential reassociation by any particular L-chain was the V kappa-segment and that the effects of the J kappa-segment could not be observed where a high degree of diversity in the V-segments existed. Furthermore, while the results implied that specific pairs of VH- and VL-domains had a higher affinity for each other, this was not a necessary criterion in the formation of autologous pairs of H- and L-chains as demonstrated by the preferential heterologous reassociation of the V kappa 21 L-chains over the autologous anti-PC L-chains. These results were consistent with the independent, random rearrangement of immunoglobulin H- and L-chain V-domain gene segments and predict that the hypothetical repertoire of antibodies is not limited by the selection of specific pairs of high-affinity VH-VL domains.

Amino Acid Sequence↗
PubMed1989

Spontaneous junction potentials and slow waves in the circular muscle of isolated segments of guinea-pig ileum.

Spontaneous electrical activity was recorded with intracellular microelectrodes from cells within the circular muscle of isolated, 2 cm long, intact segments of guinea-pig ileum that were unstretched, and in segments that had been slit open along the entire length of either their mesenteric or antimesenteric border and pinned flat under a minimum of tension. Intact segments usually exhibited fast spontaneous irregular oscillations in membrane potential (mean 1.6 Hz) which were unaffected by hyoscine (0.5 microM), the substance P antagonist D-Arg1, D-Pro2, D-Trp7.9, Leu11-substance P (10 microM), hexamethonium (100 microM), propranolol (1 microM) or phentolamine (1 microM) but were blocked by tetrodotoxin (0.4 microM) or apamin (0.4 microM). This irregular spontaneous activity is deduced to be due to ongoing firing of inhibitory motor neurons. After blockade with apamin or tetrodotoxin, a slow wave-like activity with a mean frequency of 16.4 cycles/min and maximum amplitude 2-14 mV was observed in 47% of intact segments. The amplitude of slow waves waxed and waned with a mean frequency of 0.9 cycles/min. Spontaneous cholinergic (hyoscine-sensitive) excitatory junction potentials were observed in some preparations. In contrast, in the majority of opened segments the resting membrane potential was quite stable, although slow waves that were similar to those in intact segments were observed in 14% of preparations. These studies indicate that spontaneous inhibitory junction potentials and slow waves can be recorded in intact segments of guinea-pig ileum. Their relative absence in opened segments suggests their normal expression is facilitated by the circumferential integrity of the intestine.

Animals↗
PubMed1993

Significance of exercise-induced ST-segment deviation in right-sided chest leads in the diagnosis of right ventricular ischemia.

Seventy-three patients were subjected to bicycle ergometry and exercise-induced ST-segment changes in right-sided chest leads were correlated with changes in conventional leads. ST-segment elevation in right-sided chest leads was found to be more frequent than ST-segment depression. ST-segment elevation in right-sided chest leads was commonly reciprocal to ST-segment depression in leads V3 to V7, indicating that this change is usually secondary to left ventricular subendocardial ischemia, rather than to right ventricular ischemia. ST-segment depression in right-sided chest leads was mostly a primary change indicating right ventricular subendocardial or posterior wall ischemia. It is, therefore, felt that ST-segment depression in right-sided chest leads is more sensitive and specific for right ventricular ischemia than ST-segment elevation in these leads.

Adult↗
PubMed1996

Planning and delivering high doses to targets surrounding the spinal cord at the lower neck and upper mediastinal levels: static beam-segmentation technique executed with a multileaf collimator.

BACKGROUND AND PURPOSE: It remains a technical challenge to limit the dose to the spinal cord below tolerance if, in head and neck or thyroid cancer, the planning target volume reaches to a level below the shoulders. In order to avoid these dose limitations, we developed a standard plan involving Beam Intensity Modulation (BIM) executed by a static technique of beam segmentation. In this standard plan, many machine parameters (gantry angles, couch position, relative beam and segment weights) as well as the beam segmentation rules were identical for all patients. MATERIALS AND METHODS: The standard plan involved: the use of static beams with a single isocenter; BIM by field segmentation executable with a standard Philips multileaf collimator; virtual simulation and dose computation on a general 3D-planning system (Sherouse's GRATIS); heuristic computation of segment intensities and optimization (improving the dose distribution and reducing the execution time) by human intelligence. The standard plan used 20 segments spread over 8 gantry angles plus 2 non-segmented wedged beams (2 gantry angles). RESULTS: The dose that could be achieved at the lowest target voxel, without exceeding tolerance of the spinal cord (50 Gy at highest voxel) was 70-80 Gy. The in-target 3D dose-inhomogeneity was approximately 25%. The shortest time of execution of a treatment (22 segments) on a patient (unpublished) was 25 min. CONCLUSIONS: A heuristic model has been developed and investigated to obtain a 3D concave dose distribution applicable to irradiate targets in the lower neck and upper mediastinal regions. The technique spares efficiently the spinal cord and allows the delivery of higher target doses than with conventional techniques. It can be planned as a standard plan using conventional 3D-planning technology. The routine clinical implementation is performed with commercially available equipment, however, at the expense of extended execution times.

Dose-Response Relationship, Radiation↗
PubMed1994

Extent of early ST segment elevation resolution: a simple but strong predictor of outcome in patients with acute myocardial infarction.

OBJECTIVES: This study proposed to verify the prognostic power of early ST segment elevation resolution in patients with acute myocardial infarction from the Intravenous Streptokinase in Acute Myocardial Infarction study data base. BACKGROUND: Data from a small prospective study suggested that use of two cutoff points for three different levels of ST segment resolution 3 h after the start of thrombolysis may be an efficient way to predict outcome in an individual patient. METHODS: The three groups of ST segment resolution were defined as 1) complete resolution (> or = 70% [552 patients]) or only slight ST segment elevation (127 patients); 2) partial resolution (< 70% to 30% [475 patients]); 3) no resolution (< 30% to > 0% [362 patients]). Infarct size was measured from creatine kinase isoenzyme, MB fraction, release and from the number of Q waves. Left ventricular function was assessed in 818 patients 1 month after infarction. RESULTS: For complete, partial and no ST segment resolution 3 h after the start of streptokinase or placebo infusion, enzyme release was 1.2, 1.8 and 2.1 IU/ml x h; number of Q waves 1.7, 2.5 and 3.0; and ejection fraction 60%, 53% and 49%, respectively (all adjusted p = 0.0000). Mortality rate at 21 days was 2.2%, 3.4% and 8.6%, respectively. No ST segment resolution was the most powerful independent predictor of early mortality (p = 0.0001). Survival rate curves at 6-year follow-up showed significant mortality differences with increasing divergence (p = 0.0003 anterior infarction; p = 0.005 inferior infarction). In subgroups with an overall higher risk of dying, mortality was strongly determined by the extent of early ST segment resolution. CONCLUSIONS: The extent of ST segment elevation resolution conveys useful early information about outcome in an individual patient after acute myocardial infarction.

Aged↗
PubMed1994

Balloon angioplasty results in increased segmental coronary distensibility: a likely mechanism of percutaneous transluminal coronary angioplasty.

OBJECTIVES: The purpose of this study was to evaluate the hypothesis that the increase in lumen area induced by percutaneous transluminal coronary angioplasty is secondary to a change in lesion (segmental) distensibility. BACKGROUND: Despite the widespread use of coronary angioplasty, the precise mechanism (or mechanisms) of lumen area improvement remains poorly understood. METHODS: Quantitative coronary angiography was used to measure the minimal (contrast agent filled) balloon diameters at 1 to 5 atm, inclusive, during the first and final balloon inflations in 24 lesions successfully treated with coronary angioplasty. To rule out possible confounding effects due to changes in balloon material distensibility during repeated inflations, five control balloons were studied ex vivo. In parallel, intravascular ultrasound imaging was utilized to compare the segmental distensibility (change in lumen area during the cardiac cycle) of eight disease-free and seven mildly diseased coronary segments and seven segments after successful balloon angioplasty. RESULTS: Minimal balloon diameters increased significantly between the first and final inflations (46%, 33%, 26%, 14% and 10% at 1, 2, 3, 4 and 5 atm, respectively, all p < 0.0001), demonstrating an increase in arterial distensibility after successful coronary angioplasty. No significant changes in balloon diameters were observed during sequential initial inflations at 1 and 2 atm (n = 5). Minimal increases in balloon diameters were observed during repeated balloon inflations in the ex vivo studies (4.9 +/- 1% [mean +/- SEM]). A distensibility index, derived from the intravascular ultrasound data, was not different between the balloon-dilated and the normal segments but was significantly lower in mildly diseased sites (14.7 +/- 2.2 vs. 12.9 +/- 1.2 vs. 6.9 +/- 1.9, respectively, p < 0.05) despite a smaller plaque area (7.3 +/- 1 vs. 11.3 +/- 1 mm2, proximal/nondilated vs. dilated segments, respectively, p < 0.05). CONCLUSIONS: Coronary distensibility is significantly impaired in atherosclerotically diseased coronary segments and increases significantly after balloon angioplasty. This increase in segmental coronary compliance after coronary angioplasty may create a larger lumen area by allowing the vessel to distend in response to normal intraarterial pressure.

Adult↗
PubMed1996

Prognostic significance of precordial ST segment depression on admission electrocardiogram in patients with inferior wall myocardial infarction.

OBJECTIVES: This study assessed retrospectively the correlation between the pattern of precordial ST segment depression on the admission electrocardiogram (ECG) and hospital mortality in patients with an inferior myocardial infarction treated with intravenous thrombolytic therapy. BACKGROUND: Previous studies have shown that in acute inferior myocardial infarction, ST segment depression in the precordial leads is associated with increased hospital mortality. However, the significance of the different patterns of precordial ST segment depression has been evaluated in only two previous studies. METHODS: The study included 1,321 patients (1,020 men) who enrolled in the Global Utilization of Streptokinase and t-PA for Occluded Coronary Arteries (GUSTO-I) trial in Israel and received intravenous thrombolytic therapy. Patients with an ST segment elevation > or = 0.1 mV in at least two of the inferior leads were included. Patients were classified into four groups on the basis of their admission ECG: group I = patients with no precordial ST segment depression (n = 346); group II = those for whom the sum of ST segment depression in leads V1 to V3 was greater than that in leads V4 to V6 (n = 700); group III = those for whom the sum of ST depression in leads V1 to V3 was equal to that in leads V4 to V6 (n = 162); group IV = those with maximal ST depression in leads V4 to V6 (n = 113). RESULTS: The overall hospital mortality rate was 3.6% (48 patients): for groups I, II, III and IV it was 2.9%, 2.8%, 4.3% and 9.7%, respectively. Multivariable logistic regression analysis confirmed that hospital mortality was independently associated with the pattern of precordial ST segment depression. The odd ratios in group IV relative to group I was 2.78 (95% confidence interval 1.26 to 6.13, p = 0.007). CONCLUSIONS: The risk of mortality is higher in patients with an inferior myocardial infarction and maximal ST segment depression in precordial leads V4 to V6 versus precordial leads V1 to V3 on the admission ECG.

Case-Control Studies↗
PubMedDate not supplied

Local segmentation of biomedical images.

In this paper, a new algorithm for local segmentation of biomedical images is presented. First, a relatively small region is selected for segmentation on the basis of dispersion measurement of local gray values. This small region is then segmented using a segmentation algorithm based on quantization approach. While quantizing a signal, the range of input signal is divided into a number of segments. All signal values within a segment are assigned a unique reconstruction value. In segmentation of gray level images, the problem is to classify or code gray values of the pixels into two or more groups. An N-level threshold selection method for segmentation thus becomes the design of an N-level optimal quantizer. This new approach is suitable for a number of biomedical applications where the objects of interest appear as small and localized in the images. Some experimental results are also provided which illustrate the success of the new scheme.

Algorithms↗
PubMed2004

Mitochondrial accumulation in the distal part of the initial segment of chicken spinal motoneurons.

The axonal initial segment is the initiation site of action potentials and is characterized morphologically by a dense undercoating and fascicles of microtubules connected by cross-bridges. In order to analyze subcellular structures in the initial segment, we made serial transverse sections of initial segments of identified chicken motoneurons by retrograde transport of horseradish peroxidase (HRP) injected into the muscle. The mean (+/-SD) length of the initial segment was 28.1+/-2.3 microm (n=6). Mitochondria accumulated in the distal part of the initial segment, which was 1.4-6.9 microm in length (5-23% of the total length of the initial segment). In the transverse section of the distal part, mitochondrial density was 15.8+/-6.2% (n=5), while in the middle and proximal parts it was 6.1+/-1.6% and 5.6+/-1.4%, respectively. Mitochondrial accumulation was observed in common in phasic and tonic motoneurons in the chicken, and also observed in the distal part of the initial segment of the large ventral horn neurons of the chicken without HRP injection. These findings suggest that accumulated mitochondria play an important role in maintaining the physiological function of the distal part of the motoneuron initial segment.

Animals↗
PubMed2005

The impact of total lumbar disc replacement on segmental and total lumbar lordosis.

BACKGROUND: One of the goals of total lumbar disc replacement is restoration of the physiological sagittal alignment. There is little evidence if this goal is reached in vivo and further affects the clinical outcome. METHODS: In 29 patients segmental lordosis and total lumbar lordosis were measured on X-rays pre- and postoperatively. The functional outcome was evaluated prospectively with the Visuell Analogue Scale, Oswestry Low Back Pain Disability Questionnaire and Short Form 36 Health Survey Questionnaire. FINDINGS: Total disc replacement increased segmental lordosis significantly while total lumbar lordosis remained unchanged. Preoperative segmental/total lumbar lordosis was physiological in 52%/91% of the patients. Postoperatively these values changed to 72% for segmental- and 94% for total lumbar lordosis. No difference could be observed in clinical outcome measures in patients with physiological and unphysiological segmental lordosis. INTERPRETATION: Monosegmental total disc replacement increases the segmental lordosis in most of the cases while preserving the total lumbar lordosis which produces a decrease of lordotic angle in the adjacent segment(s). Although short term clinical results are not affected, the segmental lordosis increase and adjacent segment(s) alteration may influence long term outcome.

Adult↗
PubMed2006

Automated detection of videotaped neonatal seizures based on motion segmentation methods.

OBJECTIVE: This study was aimed at the development of a seizure detection system by training neural networks using quantitative motion information extracted by motion segmentation methods from short video recordings of infants monitored for seizures. METHODS: The motion of the infants' body parts was quantified by temporal motion strength signals extracted from video recordings by motion segmentation methods based on optical flow computation. The area of each frame occupied by the infants' moving body parts was segmented by direct thresholding, by clustering of the pixel velocities, and by clustering the motion parameters obtained by fitting an affine model to the pixel velocities. The computational tools and procedures developed for automated seizure detection were tested and evaluated on 240 short video segments selected and labeled by physicians from a set of video recordings of 54 patients exhibiting myoclonic seizures (80 segments), focal clonic seizures (80 segments), and random infant movements (80 segments). RESULTS: The experimental study described in this paper provided the basis for selecting the most effective strategy for training neural networks to detect neonatal seizures as well as the decision scheme used for interpreting the responses of the trained neural networks. Depending on the decision scheme used for interpreting the responses of the trained neural networks, the best neural networks exhibited sensitivity above 90% or specificity above 90%. CONCLUSIONS: The best among the motion segmentation methods developed in this study produced quantitative features that constitute a reliable basis for detecting myoclonic and focal clonic neonatal seizures. The performance targets of this phase of the project may be achieved by combining the quantitative features described in this paper with those obtained by analyzing motion trajectory signals produced by motion tracking methods. SIGNIFICANCE: A video system based upon automated analysis potentially offers a number of advantages. Infants who are at risk for seizures could be monitored continuously using relatively inexpensive and non-invasive video techniques that supplement direct observation by nursery personnel. This would represent a major advance in seizure surveillance and offers the possibility for earlier identification of potential neurological problems and subsequent intervention.

Cluster Analysis↗