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Cinevideodensitometric quantification of relative coronary arterial stenosis: application to evaluating candidates for percutaneous transluminal coronary angioplasty.

As an alternative to visual interpretations of subjects' angiograms, coronary arteries dilated by percutaneous transluminal coronary angioplasty (PTCA) were evaluated using cinevideodensitometry, and the results were compared with those obtained by the edge detection method. Coronary arteriograms were obtained in various projections and suitable frames were selected for analysis. The frames were transformed to digitized images (512 X 512 X 8 bits) with an image analyzer (MIPRON 1), and cinevideodensitometric and edge detection analyses were performed. Phantom models of various shapes were opacified with contrast medium and were used to test our system. The cineangiograms of 58 patients with ischemic heart disease, 28 of whom had underwent PTCA, were analyzed. A highly linear correlation was observed between the cross-sectional areas of the phantoms and the summed gray levels measured using cinevideodensitometry. Percent area stenosis evaluated by the two methods was accurate and reproducible in measuring the symmetrical stenosis models. However, for the model of asymmetrical stenosis, the measurement by the edge detection method differed according to various projections. Similar results were obtained measuring asymmetrical stenosis in the right coronary artery in vivo in various projections. Based on these experimental results, coronary stenoses dilated by PTCA were evaluated. Prior to PTCA, coronary arterial stenosis measured using the two methods closely approximated each other. However, following PTCA, there were discrepancies between the measurements by the two methods in six cases. This can be accounted for by asymmetrical changes in a luminal cross-section, which cannot be accurately assessed using the edge detection method in single plane projection. In conclusion, cinevideodensitometric measurements of relative coronary arterial stenosis were objective, accurate, and reproducible. According to cinevideodensitometric analysis, eccentric lesions can be measured using a single projection, and tracing arterial borders is unnecessary. It is a useful means in measuring quantitatively the degree of dilatation of coronary arterial stenosis accomplished by PTCA.

Angiography↗

Parietal and cingulate processes in central pain. A combined positron emission tomography (PET) and functional magnetic resonance imaging (fMRI) study of an unusual case.

Parietal, insular and anterior cingulate cortices are involved in the processing of noxious inputs and genesis of pain sensation. Parietal lesions may generate central pain by mechanisms generally assumed to involve the 'medial' pain system (i.e. medial thalamic nuclei and anterior cingulate cortex (ACC)). We report here PET and fMRI data in a patient who developed central pain and allodynia in her left side after a bifocal infarct involving both the right parietal cortex (SI and SII) and the right ACC (Brodmann areas 24 and 32), thus questioning the schematic representation of cortical pain processing. No rCBF increase was found in any part of the residual cingulate cortices, neither in the basal state (which included spontaneous pain and extended hypoperfusion around the infarct), nor during left allodynic pain. Thus, as previously observed in patients with lateral medullary infarct, neither spontaneous pain nor allodynia reproduce the cingulate activation observed after noxious pain in normal subjects. Conversely, both PET and fMRI data argue in favour of plastic changes in the 'lateral discriminative' pain system. Particularly, allodynia was associated with increased activity anteriorly to the infarct in the right insula/SII cortex. This response is likely to be responsible for the strange and very unpleasant allodynic sensation elicited on the left side by a non-noxious stimulation.

Brain Mapping↗

Distinct transcriptional regulatory mechanisms underlie left-right asymmetric expression of lefty-1 and lefty-2.

Both lefty-1 and lefty-2 genes are expressed on the left side of developing mouse embryos and are implicated in left-right (L-R) axis formation. With the use of transgenic analysis, the transcriptional regulatory regions of these genes responsible for their L-R asymmetric expression have now been investigated. The 9.5-kb upstream region of lefty-1 and the 5.5-kb upstream region of lefty-2 reproduced the expression pattern of the corresponding gene. Examination of deletion constructs revealed the presence of a left side-specific enhancer (ASE) that is essential and sufficient for lefty-2 asymmetric expression. In contrast, the asymmetric expression of lefty-1 was shown to be determined by a combination of bilateral enhancers and a right side-specific silencer (RSS). The 9. 5-kb region of lefty-1 and the 5.5-kb region of lefty-2 responded to iv and inv, upstream genes of lefty-1 and lefty-2. The regulation of lefty-2 by iv and inv was mediated by ASE. These results suggest that, in spite of the similarities between lefty-1 and lefty-2, different regulatory mechanisms underlie their asymmetric expression.

Animals↗

Influence of infarct age on reproducibility of ventricular tachycardia induction in a canine model.

The inducibility and reproducibility of ventricular tachycardia were evaluated in 97 dogs after myocardial infarction produced by single stage coronary artery ligation. Arrhythmia induction was performed with use of an endocardial electrode catheter positioned at the right ventricular apex before each study. An aggressive protocol of programmed stimulation was used, employing up to seven extrastimuli and three attempts at arrhythmia induction in each study. Electrophysiologic study was performed in individual dogs at the following times after infarction: 1) 7.7 +/- 0.3 and 15 +/- 0.2 days (34 consecutive dogs); 2) 14 +/- 0.6 and 26 +/- 1.7 days (24 selected dogs); 19 +/- 2 and 43 +/- 3 days (12 selected dogs); 4) 36 +/- 2 and 60 +/- 6 days (8 selected dogs); and 5) 59 +/- 12 and 130 +/- 10 days (3 selected dogs). Inducibility of ventricular tachycardia decreased significantly from 74% 1 week after infarction to 41% 2 weeks after infarction. Thus, early reproducibility was low (48%). Reproducibility increased thereafter, with 88% of the dogs having reproducible ventricular tachycardia between 2 and 4 weeks (p less than 0.025) and 100% having reproducibly inducible ventricular tachycardia between 4 weeks and 4 months after infarction. Dogs with no inducible arrhythmia early after infarction did not develop inducible ventricular tachycardia or fibrillation at later studies. Twelve dogs developed spontaneous ventricular tachycardia or sudden arrhythmic death late after infarction. Overall, 22% of dogs with inducible ventricular tachycardia with a cycle length greater than 140 ms developed spontaneous ventricular tachycardia or sudden death. Arrhythmia induction decreases significantly during the 1st 2 weeks after myocardial infarction, but long-term reproducibility of ventricular tachycardia induced greater than or equal to 2 weeks after infarction is very high. This canine model of long-term, reliably inducible ventricular tachycardia is suitable for investigation of antiarrhythmic drugs, surgery and other interventions.

Animals↗

Bronchial electrocardiography to determine left or right main bronchial placement of an endotracheal suction catheter tip.

OBJECTIVE: To assess the utility of a blue lined angle tipped and electrode tipped catheter, to guide left and right main bronchus cannulation. DESIGN: A prospective study. SETTING: An 11-bed general intensive care unit in a 900-bed teaching hospital. PATIENTS: 50 intubated intensive care patients, in sinus rhythm with normal P and QRS mean frontal axis, who required endobronchial suctioning for routine respiratory management. INTERVENTIONS: Endobronchial electrocardiography was used to position a blue lined angle tipped and electrode tipped suction catheter into the right and left main bronchi. RESULTS: Selective cannulation of the left main bronchi was determined by observing a biphasic or inverted P wave in 42 patients, or biphasic or inverted QRS complex in 31 patients. In 8 patients in whom no changes in the ECG were found, bronchoscopic placement of an ECG electrode into the left main bronchus demonstrated a biphasic or inverted P wave in 8 patients and a biphasic QRS complex in 3 patients, confirming the failure to cannulate the left main bronchus in these 8 patients. CONCLUSIONS: Using a blue lined, angle tipped and electrode tipped catheter for endotracheal suctioning, endobronchial electrocardiography may be a simple method to signal left or right main bronchus cannulation.

Arrhythmias, Cardiac↗

The Tei index permits evaluation of cardiopulmonary function during inhaled nitric oxide therapy in the hypoxic newborn piglet.

The purpose of this study was to test the effectiveness of a new Doppler index combining systolic and diastolic time intervals (the Tei index) in the prospective assessment of ventricular function and pulmonary circulation in a newborn piglet model with hypoxic pulmonary hypertension during inhaled nitric oxide (NO). Piglets were prepared for the experiments under normal air, hypoxia, and hypoxia-with-inhaled-NO conditions. Complete two-dimensional Doppler echocardiographic examinations were performed in each condition. The right-ventricle (RV) Tei index increased with hypoxia and decreased following the inhalation of NO. Furthermore, there was a direct correlation between the individual changes in the RV Tei index and individual changes in mean pulmonary arterial pressure in each condition. We conclude that the Tei index is useful for assessing cardiac function and pulmonary circulation in hypoxic pulmonary hypertension during inhaled NO. These results suggest that the Tei index provides an objective assessment of persistent pulmonary hypertension of the newborn.

Animals↗

Visual word recognition in the left and right hemispheres: anatomical and functional correlates of peripheral alexias.

According to a simple anatomical and functional model of word reading, letters displayed in one hemifield are first analysed through a cascade of contralateral retinotopic areas, which compute increasingly abstract representations. Eventually, an invariant representation of letter identities is created in the visual word form area (VWFA), reproducibly located within the left occipito-temporal sulcus. The VWFA then projects to structures involved in phonological or lexico-semantic processing. This model yields detailed predictions on the reading impairments that may follow left occipitotemporal lesions. Those predictions were confronted to behavioural, anatomical and functional MRI data gathered in normals and in patients suffering from left posterior cerebral artery infarcts. In normal subjects, alphabetic stimuli activated both the VWFA and the right-hemispheric symmetrical region (R-VWFA) relative to fixation, but only the VWFA showed a preference for alphabetic strings over simple chequerboards. The comparison of normalized brain lesions with reading-induced activations showed that the critical lesion site for the classical syndrome of pure alexia can be tightly localized to the VWFA. Reading impairments resulting from deafferentation of an intact VWFA from right- or left-hemispheric input were dissected using the same methods, shedding light on the connectivity of the VWFA. Finally, the putative role of right-hemispheric processing in the letter-by-letter reading strategy was clarified. In a letter-by-letter reader, the R-VWFA assumed some of the functional properties normally specific to the VWFA. These data corroborate our initial model of normal word perception and underline that an alternative right-hemispheric pathway can underlie functional recovery from alexia.

Adult↗

Reproducibility and accuracy of measurements with a hand held autorefractor in children.

AIM: To determine reproducibility and accuracy of the Nikon Retinomax autorefractor when used with children who were made cycloplegic. METHODS: Autorefraction and retinoscopy or subjectively refined retinoscopy (where, under the patient's direction, the refraction was varied until the best visual acuity was achieved) were performed on the right eye of 47 children, age 11-93 months. Autorefraction was performed using the Nikon Retinomax, which provides up to eight measured values of refractive error and one representative measurement of refractive error. RESULTS: Autorefractor measurements were successfully obtained from 7/9 children age 3 years or younger, and from all older children. Vector methods were used to calculate differences. Retinomax reproducibility averaged 0.43 D. Unbiased Retinomax and retinoscopy measurements differed by an average of 0.82 D. Unbiased Retinomax and subjectively refined retinoscopy differed by an average of 1.03 D. CONCLUSIONS: Reproducibility of Retinomax measured values in children is comparable with reproducibility of retinoscopy, subjective refraction, and autorefraction measurements in adults. Agreement between Retinomax and retinoscopy and agreement between Retinomax and subjective refinement in children is comparable with agreement between autorefraction and subjective refraction in adults. The study indicates that the Retinomax is a useful instrument for measuring refractive errors in young children.

Child↗

Reproducibility of electrical impedance tomographic spectroscopy (EITS) parametric images of neonatal lungs.

The reproducibility of electrical impedance tomographic spectroscopy (EITS) images of neonatal lungs have been investigated in 11 clinically stable babies. We have used the Sheffield Mark IIIa EITS system. An average inspiration frame was generated from the data frames associated with maximum inspiration. Frequency images were reconstructed from these frames. The frequency images were analysed to locate the pixel with the maximum change in the right lung field. The change was defined as the 614 kHz measurement relative to 9.6 kHz. A 3 x 3 pixel region of interest was centred at this point. The changes in impedance with frequency for this region of interest show good overall reproducibility between electrode applications for eight frequencies (95% limits of agreement +/- 28%). This reproducibility is improved (95% limits of agreement +/- 13%) by omitting the highest frequency (1.2 MHz) which is most subject to system noise. The parameters for the Cole model derived from data with the highest frequency omitted are less reproducible between electrode applications (95% limits of agreement, R/S +/- 0.83, fc +/- 81.6, RC +/- 0.52, SC +/- 0.39). We suspect that the parametric model used may have an effect on this. The signals recorded at the highest frequency (1.2 MHz) are a major source of variability. The reproducibility results are improved by omitting this frequency from the analysis.

Body Water↗

Reproducibility of surface EMG during dynamic shoulder forward flexions: a study of clinically healthy subjects.

There is a shortage of studies concerning the reproducibility of surface electromyography (EMG) during dynamic contractions. The movement per se introduces factors that could have the potential to affect the characteristics of the electromyogram. The aim of this study was to investigate the during-the-day reproducibility (using intra-class coefficient, ICC) of the peak torque (PT) and the EMG variables (without removing electrodes) of dynamic shoulder forward flexions. Eleven healthy women performed three sets of 10 dynamic maximum right-shoulder flexions at 1 h intervals using an isokinetic dynamometer. The PT of each flexion was determined. EMG signals were recorded from four muscles (trapezius, deltoid, infraspinatus and biceps brachii) using surface electrodes, and the mean frequency of the power spectrum (MNF [Hz]) and the signal amplitude (RMS [microV]), were computed. The ability to relax between maximum flexions was calculated as a ratio between the RMS during the passive extension phase and the RMS during the active flexion phase of each contraction cycle. This ratio is the signal amplitude ratio (SAR). The present study showed good reproducibility for PT, MNF and RMS, while the reproducibility of SAR was generally acceptable (fair) according to the criteria used.

Adult↗

Respiratory gating for liver tumors: use in dose escalation.

PURPOSE: To determine the clinical impact of the Varian Real-Time Position Monitor (RPM) respiratory gating system for treatment of liver tumors. METHODS AND MATERIALS: Ten patients with liver tumors were selected for evaluation of this passive system, which tracks motion of reflective markers mounted on the abdomen with an infrared-sensitive camera. At simulation, a fluoroscopic movie, breathing trace, and CT scans synchronized at end-expiration (E-E) and end-inspiration were acquired in treatment position using the RPM system. Organs and gross tumor volume were contoured on each CT. Each organ's positional change between two scan sets was quantified by calculation of the center of volume shift and an "index coefficient," defined as the volume common to the two versions of the organ to the volume included in at least one (intersection/union). Treatment dose was determined by use of normal tissue complication probability calculations and dose-volume histograms. Gated portal images were obtained to monitor gating reproducibility with treatment. RESULTS: Eight patients received 177 treatments with RPM gating. Average superior-to-inferior (SI) diaphragm motion on initial fluoroscopy was reduced from 22.7 mm without gating to 5.1 mm with gating. Comparing end-inspiration to E-E CT scans, average SI movement of the right diaphragm was 11.5 mm vs. 2.2 mm for two E-E CT scans. For all organs, average E-I SI organ motion was 12.8 mm vs. 2.0 mm for E-E studies. Index coefficients were closer to 1.0 for E-E than end-inspiration scans, indicating gating reproducibility. The average SI displacement of diaphragm apex on gated portal images compared with DRR was 2.3 mm. Treatment was prolonged less than 10 minutes with gating. The reproducible decrease in organ motion with gating enabled reduction in gross tumor volume-to-planning target volume margin from 2 to 1 cm. This allowed for calculated dose increases of 7%-27% (median: 21.3%) in 6 patients and enabled treatment in 2. CONCLUSION: Gating of radiotherapy for liver tumors enables safe margin reduction on tumor volume, which, in turn, may allow for dose escalation.

Aged↗

Limb and hemispatial hypometria.

In a previous study, we demonstrated that unilateral cerebral lesions produce hypometric limb movements of the contralateral arm and hemispatial (i.e., directional) hypometria for movements towards contralateral hemispace. In the present study, we investigated 10 patients with right cerebral lesions and 25 healthy controls using a task to uncouple deficits in sensory perceptual systems and motor-action output systems on directional hypometria. This task required participants, with their eyes closed, to reproduce lateral and medial horizontal displacements (15-27 cm) with each arm. Each participant was seated at a waist high table and had their hand placed at an origin point aligned with the axillary fold on the same side. Their hand was moved by the investigator from the origin point to a target point and brought back to the point of origin (input displacement). The participant was then asked to return their hand to either the same target point or to an equidistant target point in the opposite direction. Healthy dextral participants were significantly more hypometric with their right arm, but patients with right cerebral lesions exhibited an opposite pattern with overall left arm hypometria. In addition, patients were significantly more hypometric for movements when output displacements were toward left hemispace. No effect was found for direction of sensory input. The results suggest that the directional hypometria is predominantly produced by hemispatial output deficits.

Adolescent↗

Anatomic and electrophysiologic correlates of ventricular tachycardia requiring left ventricular stimulation.

In 108 patients with reproducible initiation of ventricular tachycardia by programmed ventricular stimulation, the ventricular tachycardia was initiated only by left ventricular stimulation in 12 (11 percent). Programmed ventricular stimulation included single and double extrastimuli extrastimuli at three cycle lengths and bursts of rapid pacing to cycle lengths of 250 ms. Clinical, electrocardiographic, angiographic, hemodynamic and electrophysiologic data were available in 74 of 96 patients with ventricular tachycardia initiated by right ventricular stimulation (Group A) and in all 12 patients with ventricular tachycardia initiated only by left ventricular stimulation (Group B). there were no significant differences between Groups A and B in clinical characteristics, hemodynamics or presence and site of infarction or aneurysm. Comparison of electrophysiologic variables revealed no significant differences between Groups A and B mean A-H interval (92 +/- 22 versus 89 +/- 15 ms, respectively), H-V interval (59 +/- 15 versus 59 +/- 15 ms) or right ventricular (241 +/- 38 versus 260 +/- 40 ms) or left ventricular (232 +/- 28 versus 251 +/- 42 ms) effective refractory period. Ventricular tachycardia with right bundle branch block and superior axis was more prevalent in Group B (92 percent versus 31 percent, p less than 0.001) but was observed in 32 patients in Group A. It is concluded that 11 percent of patients with clinically documented sustained ventricular tachycardia will require left ventricular programmed stimulation to reproducibly initiate the tachycardia. No clinical, anatomic, electrocardiographic or electrophysiologic features can predict whether left ventricular programmed stimulation will be required. Because initiation of ventricular tachycardia by programmed ventricular stimulation has important prognostic and therapeutic implications in such patients, stimulation should be performed from the left ventricle when the tachycardia is not initiated by stimulation from the right ventricle.

Adolescent↗

The reference values of the T-wave of the patellar tendon reflex in normal dogs.

The T-wave of the patellar tendon reflex (PTR) was recorded in 24 neurologically normal dogs. The surface electromyogram (EMG) was recorded as the T-wave from the vastus lateralis muscle (VL) in response to percussion of the patellar tendon. The distance of the reflex arc (DRA) was measured along the straight line between the spinous process of L5 and the greater trochanter (GT), and between GT and the patellar ligament (PL). There was a significant correlation (P<0.001) of the latency with the DRA on each side, but no difference in the slopes of the relationships between right and left VL was shown. The regression line between the DRA and the latency of all data was Y = 0.0216X + 1.693, where Y = latency in ms, X = DRA in mm. The mixed sensory-motor conduction velocity was estimated as 84.6 +/- 5.5 m/s. In contrast, there was no significant correlation between the DRA and the amplitude of the T-waves. The mean (mean-CV) and standard deviation (SD-CV) of all CV (coefficient of variation) in each dog were 9.14 +/- 3.65% in latency and 3.54 +/- 1.14% in amplitude, indicating that the use of a simple hand-held reflex hammer is sufficient to record the reproducible T-wave of the PTR even in unanesthetized dogs. This method was applied to a case with minimal paraparesis, and the latency of the T-wave of the PTR in the right hind limb with slight proprioceptive deficit was outside of the upper limit of the 95% confidence interval between latency and the DRA. In conclusion, this method may be used in neurological diagnosis to quantify more precisely the PTR in dogs.

Animals↗

Collagen metabolism during the healing process of the cauterized rat cornea. An experimental study.

Attempts were made (1) to develop an appropriate method for producing standardizable and reproducible experimental opacities of the cornea of rats and (2) to study quantitatively the course and intensity of the healing process of these corneal wounds. The right cornea of rats was cauterized by drops of 1.5 N HC1 over 30 s; the left one served as a control. The spontaneous course of wound healing, as well as the possible effect on this process of spray treatment with iodine brine or, for comparative purposes, with isotonic NaCl, was studied for 10 consecutive days by measuring the 24-h incorporation of 14C-labelled proline as a measure of de novo collagen synthesis. Spray treatment (1) abolishes the transient inhibition of proline incorporation observed in the unsprayed cornea on the first day after injury and (2) significantly advances the maximum collagen synthesis rate from day 3-4 to day 2 after the wound occurred. The position and magnitude of the 14C-proline incorporation peak are considered to be useful parameters for estimating corneal wound healing activity and its alteration by various agents. However, in this experimental design, it could not be proved that iodine has a specific effect.

Administration, Topical↗

Functional magnetic resonance imaging of the primary motor cortex in humans: response to increased functional demands.

Functional magnetic resonance imaging (fMRI) studies have been performed on 20 right handed volunteers at 1.5 Tesla using echo planar imaging (EPI) protocol. Index finger tapping invoked localized activation in the primary motor area. Consistent and highly reproducible activation in the primary motor area was observed in six different sessions of a volunteer over a period of one month. Increased tapping rate resulted in increase in the blood oxygenation level dependent (BOLD) signal intensity as well as the volume/area of activation (pixels) in the contralateral primary motor area up to tapping rate of 120 taps/min (2 Hz), beyond which it saturates. Activation in supplementary motor area was also observed. The obtained results are correlated to increased functional demands.

Adult↗

[Taking into consideration gender and sex. New chances to improve the quality of epidemiological and health research].

Researchers who apply for project funding at the European level or at German Federal Ministries must take into account the gender aspects of their proposals as well as in the realization of these projects (gender mainstreaming) more and more often. The promotion of gender equality in research and science is becoming a "mainstream" task as well as a sign of the quality of the project. In practice, however, the process of carrying out gender sensitive research must still gain momentum. This article focuses on central questions and problems: Which are the gender aspects of a certain subject? In what way do we have to design studies and research methods to be able to apprehend and discover gender aspects properly? Which strategies of evaluation are adequate? What is the best way to analyze, interpret, and communicate data? The basics will be clarified (e. g. terms like sex/gender, doing gender, the role of the "gender" category in the context of social differentiation, causes and forms of gender bias). In addition, methodological/methodical hints and instruments to avoid distortion due to the inadequate consideration of gender category in the course of research will be introduced (diagnostic brief-questionnaire according to Eichler, gender-matrix, five challenges according to Doyal, gender adequate speech and publication).

Data Interpretation, Statistical↗

Total laparoscopic aortic surgery: transperitoneal direct approach.

OBJECTIVE: We describe the laparoscopic transperitoneal direct approach to the abdominal aorta. OPERATIVE TECHNIQUE: The patient is placed in the right lateral decubitus position, which allows dropping of the small bowel into right side of the abdomen. Anatomical exposure of the abdominal aorta follows the same steps as in open surgery. DISCUSSION: Laparoscopic transperitoneal direct approach allows a reproducible exposure of the abdominal aorta. This technique was useful when retrocolic and/or retrorenal approaches were not possible because of previous left nephrectomy.

Aorta, Abdominal↗