Cosmic ray-produced radionuclides as tracers of atmospheric precipitation processes

Through recent developments in instrumental analysis it is now possible to measure with good precision the rainwater concentrations of five short-lived radionuclides which are produced by cosmic ray spallation of atmospheric argon. These measurements provide a method for studying the in-cloud nucleation times and aerosol scavenging efficiencies, and promise to provide information onshort-term processes which occur in rain and snow formation.

Selective inhibition of inflammatory gene expression in activated T lymphocytes: a mechanism of immune suppression by thiopurines

Azathioprine and 6-mercaptopurine are antimetabolite thiopurine drugs that play important roles in the treatment of leukemia and in the management of conditions requiring immunosuppression, such as inflammatory bowel disease. The biochemical pharmacology of these drugs suggests that inhibition of purine nucleotide formation through the 6-thioguanine nucleotide metabolites is their key molecular mechanism. However, it is unclear how these metabolites suppress immunity. We hypothesized that azathioprine produces a selective inhibitory effect on activated but not quiescent T lymphocytes. We first established a model system of T lymphocyte culture with azathioprine that produced pharmacologically relevant concentrations of 6-thioguanine nucleotides. Using genome-wide expression profiling, we identified a group of azathioprine-regulated genes in quiescent and activated T lymphocytes. Several genes involved in immunity and inflammation were selectively down-regulated by azathioprine in stimulated but not quiescent cells. Quantitative reverse transcription-polymerase chain reaction for three of these genes, tumor necrosis factor-related apoptosis-inducing ligand, tumor necrosis factor receptor superfamily member 7, and alpha4-integrin, confirmed down-regulated expression of transcript levels. Tumor necrosis factor-related apoptosis-inducing ligand protein expression was further studied and found to be inhibited by azathioprine, 6-mercaptopurine, and 6-thioguanine, implying that the inhibitory effects of azathioprine on expression are mediated by 6-thioguanine nucleotides. These results therefore provide a previously unrecognized molecular mechanism for the immunosuppressive properties of thiopurine antimetabolite drugs.

Demyelination during anti-tumor necrosis factor alpha therapy with infliximab for Crohn's disease

BACKGROUND

Inflammatory demyelinating disease of the central nervous system may be linked to anti-tumor necrosis factor alpha therapy.

CASE HISTORY

A 19-year-old female with Crohn's ileocolitis developed right arm and leg numbness and right hand weakness 4 weeks after the initiation of infliximab. Neurologic examination confirmed upper and lower right extremity sensory and motor deficits. MRI examination of the head and thoracic cord showed multiple gadolinium-enhancing lesions with distribution and configuration most suggestive of multiple sclerosis or other demyelinating process. The infliximab therapy was immediately stopped and follow-up at 8 weeks revealed symptomatic improvement.

CONCLUSION

This case report describes the onset of a demyelinating process after the institution of infliximab therapy in a patient with Crohn's disease.

Erythrocyte mean corpuscular volume as a surrogate marker for 6-thioguanine nucleotide concentration monitoring in patients with inflammatory bowel disease treated with azathioprine or 6-mercaptopurine

Mean corpuscular volume may correlate with erythrocyte 6-thioguanine nucleotide concentrations in patients treated with azathioprine and 6-mercaptourine. We conducted a study of 166 patients with inflammatory bowel disease treated with azathioprine or 6-mercaptopurine to determine the relationship between mean corpuscular volume and erythrocyte 6-thioguanine nucleotide concentrations, disease activity as measured by the Inflammatory Bowel Disease Questionnaire (active disease <170, remission >170), and leukopenia. Blood was submitted for mean corpuscular volume, whole blood 6-thioguanine nucleotide concentration, and leukocyte count. The mean +/- SD mean corpuscular volume during treatment was 94.7 +/- 6.6 fL and the mean +/- SD change in mean corpuscular volume was 7.5 +/- 6.3 fL. There were significant correlations between mean corpuscular volume and erythrocyte 6-thioguanine nucleotide concentration (r(s) = 0.33, p < 0.001) and between change from baseline in mean corpuscular volume and erythrocyte 6-thioguanine nucleotide concentration (r(s) = 0.26, p = 0.001). There was no correlation between Inflammatory Bowel Disease Questionnaire scores and mean corpuscular volume values (r(s) = 0.01, p = 0.94). The mean corpuscular volume values in 55 patients with active disease and 111 patients in remission were similar (95.1 vs. 94.5 fL, p = 0.57). There was a weak negative correlation between the mean corpuscular volume and the leukocyte count, (r(s) = -0.18, p = 0.022). In patients with inflammatory bowel disease treated with azathioprine or 6-mercaptopurine, mean corpuscular volume and change from baseline in mean corpuscular volume correlated with erythrocyte 6-thioguanine nucleotide concentrations and negatively with leukocyte counts, but did not correlate with disease activity as measured by the Inflammatory Bowel Disease Questionnaire. Measurement of mean corpuscular volume is a simple and inexpensive alternative to measurement of 6-thioguanine nucleotide concentrations in patients treated with azathioprine or 6-mercaptopurine.

HIV prevention community planning and communities of color: do resources track the epidemic?

The Centers for Disease Control and Prevention (CDC) funds provided to state, local, and territorial health departments for HIV-prevention activities are prioritized with the substantial involvement of HIV-prevention community planning groups (CPGs). This article examines whether or not these funds (more than $261 million in fiscal year 1998) are allocated in a way that mirrors the HIV/AIDS epidemic in terms of race/ethnicity. AIDS prevalence data were used to reflect disease burden, and were compared to budget data submitted by health departments to the CDC. The budget data report expenditures by race/ethnicity for two major types of activities: (1) health education and risk reduction (more than $104 million); and (2) counseling, testing, referral, and partner notification (more than $91 million). The rank order correlation between funding and AIDS prevalence data for the five specific racial/ethnic categories was .900 (n = 5, p < .05) for health education and risk reduction (HERR) activities, and 1.000 (n = 5, p < .05) for counseling, testing, referral, and partner notification (CTRPN) activities. From 1997 to 1998, the proportion of funds targeted and accounted for by race/ethnicity increased from 79 percent to 88 percent for HERR, and from 71 percent to 84 percent for CTRPN activities. With regard to race/ethnicity, health departments and CPGs appear to be actively targeting and accounting for HIV prevention resources, and we will argue that relatively small changes in counseling and testing resources for African-American and Latino/Latina communities would result in a close match between AIDS prevalence data and devoted resources.

Outcomes assessment an intervention strategy to improve parental compliance to follow-up evaluations after treatment of early childhood caries using general anesthesia in a Medicaid population

Young children from low-income families are at risk for the development of early childhood caries (ECC) that can progress to severe oral disease. Treatment of this condition often requires extensive rehabilitation using general anesthesia in an ambulatory care facility. These children, presenting with neglected oral health, frequently face major obstacles to accessing dental care in a timely manner. Recently, several retrospective studies reported poor follow-up compliance (return for recall evaluations) in children treated for ECC using general anesthesia (GA). The purpose of this study was to provide a prospective analysis of an intervention strategy aimed at improving follow-up compliance in this population. Results of the analysis suggested that the insertion of an additional pre-operative consultation appointment failed to improve significantly compliance to follow-up evaluations or change parental dental health knowledge and preventive practices. Patient variables studied also failed to discriminate influences on predicting compliant behavior. Although retreatment (relapse) was prevalent among those patients who complied with follow-up evaluations, a statistically significant improvement in plaque, gingival, and mutans streptococci scores were demonstrated, following the degree of aggressive restorative treatment typically provided using general anesthesia. These findings are contrary to those reported from conventional restorative therapy and might reflect a beneficial outcome of an aggressive restorative approach. Further investigation is required to identify an intervention strategy that improves follow-up compliance and reduces the costly ravages of dental neglect in young children from low-income families.

Verifying drug abuse prevention program effects using reciprocal best friend reports

Considerable research suggests that social influences-based drug abuse prevention programming has produced the most consistently successful preventive effects. However, a common criticism of this literature is that most prevention intervention studies rely solely on self-reported substance use. The purpose of this study was to assess the effects of normative education, arguably the most successful component of social influence based prevention programs, on alcohol and cigarette consumption using both self- and reciprocal best friend reports of substance use. Analyses of subsamples of data from 11,995 students participating in the Adolescent Alcohol Prevention Trial revealed that normative education significantly delayed the onset of alcohol use across the eighth, ninth, and tenth grades among public school students. A similar but somewhat less robust pattern was found for cigarette use. These results suggest that self-report bias does not account for previous findings and demonstrate rather convincingly that normative education is an effective drug prevention strategy for public school settings.

Patient-controlled lidocaine analgesia for acromioplasty surgery

Twenty-four consecutive patients undergoing shoulder acromioplasty were given postoperative analgesia with a new method in which a patient-controlled continuous infusion of lidocaine infiltrated the subacromial space. Seventeen of the acromioplasties were done with arthroscopy, whereas 7 were performed with an open procedure. A 2% solution of lidocaine without epinephrine was used for both a continuous dose of 2 cc/h and patient-controlled interval doses of 1 cc administered at 15-minute intervals. The catheter was left in place for 72 hours. We prospectively studied complications, the patient's subjective pain level, the amount of supplementary pain medication used, and serum levels of lidocaine. In addition, we evaluated a control group of 24 patients undergoing acromioplasty by the same surgeon without the use of this method of pain control. No wound complications occurred. No adverse reactions to lidocaine or overdose of lidocaine occurred. Blood levels of lidocaine averaged 0.3 microgram/mL in the 12 patients studied. Subjective pain levels and the amount of supplementary pain medication used were both lower in the group receiving patient-controlled lidocaine analgesia at statistically significant levels (P = .168 measuring subjective pain level, and P = .0212 measuring supplementary pain medication use). Patient-controlled lidocaine analgesia in the subacromial space appears to be a safe method for achieving high levels of pain control in patients undergoing an acromioplasty.

Sexually transmitted disease prevention: adolescents' perceptions of possible side effects

Forty-eight sexually active adolescents participated in an open-ended interview about the possible secondary consequences (side effects) of implementing measures to reduce the risk of contracting a sexually transmitted disease (STD). These adolescents noted 134 different consequences, which were grouped into 15 substantive categories. When four prevention measures (using condoms, being selective about sex partner(s), being monogamous, and abstaining from sexual activity) were analyzed, different patterns of consequences that were salient to these adolescents emerged. The results are discussed in terms of their implications for understanding and improving adolescent decision making about STD prevention.

Saccades to remembered targets: the effects of smooth pursuit and illusory stimulus motion

1. Measurements were made in four normal human subjects of the accuracy of saccades to remembered locations of targets that were flashed on a 20 x 30 deg random dot display that was either stationary or moving horizontally and sinusoidally at +/-9 deg at 0.3 Hz. During the interval between the target flash and the memory-guided saccade, the "memory period" (1.4 s), subjects either fixated a stationary spot or pursued a spot moving vertically sinusoidally at +/-9 deg at 0.3 Hz. 2. When saccades were made toward the location of targets previously flashed on a stationary background as subjects fixated the stationary spot, median saccadic error was 0.93 deg horizontally and 1.1 deg vertically. These errors were greater than for saccades to visible targets, which had median values of 0.59 deg horizontally and 0.60 deg vertically. 3. When targets were flashed as subjects smoothly pursued a spot that moved vertically across the stationary background, median saccadic error was 1.1 deg horizontally and 1.2 deg vertically, thus being of similar accuracy to when targets were flashed during fixation. In addition, the vertical component of the memory-guided saccade was much more closely correlated with the "spatial error" than with the "retinal error"; this indicated that, when programming the saccade, the brain had taken into account eye movements that occurred during the memory period. 4. When saccades were made to targets flashed during attempted fixation of a stationary spot on a horizontally moving background, a condition that produces a weak Duncker-type illusion of horizontal movement of the primary target, median saccadic error increased horizontally to 3.2 deg but was 1.1 deg vertically. 5. When targets were flashed as subjects smoothly pursued a spot that moved vertically on the horizontally moving background, a condition that induces a strong illusion of diagonal target motion, median saccadic error was 4.0 deg horizontally and 1.5 deg vertically; thus the horizontal error was greater than under any other experimental condition. 6. In most trials, the initial saccade to the remembered target was followed by additional saccades while the subject was still in darkness. These secondary saccades, which were executed in the absence of visual feedback, brought the eye closer to the target location. During paradigms involving horizontal background movement, these corrections were more prominent horizontally than vertically. 7. Further measurements were made in two subjects to determine whether inaccuracy of memory-guided saccades, in the horizontal plane, was due to mislocalization at the time that the target flashed, misrepresentation of the trajectory of the pursuit eye movement during the memory period, or both. 8. The magnitude of the saccadic error, both with and without corrections made in darkness, was mislocalized by approximately 30% of the displacement of the background at the time that the target flashed. The magnitude of the saccadic error also was influenced by net movement of the background during the memory period, corresponding to approximately 25% of net background movement for the initial saccade and approximately 13% for the final eye position achieved in darkness. 9. We formulated simple linear models to test specific hypotheses about which combinations of signals best describe the observed saccadic amplitudes. We tested the possibilities that the brain made an accurate memory of target location and a reliable representation of the eye movement during the memory period, or that one or both of these was corrupted by the illusory visual stimulus. Our data were best accounted for by a model in which both the working memory of target location and the internal representation of the horizontal eye movements were corrupted by the illusory visual stimulus. We conclude that extraretinal signals played only a minor role, in comparison with visual estimates of the direction of gaze, in planning eye movements to remembered targ

Measuring eye movements during locomotion: filtering techniques for obtaining velocity signals from a video-based eye monitor

Video-based eye-tracking systems are especially suited to studying eye movements during naturally occurring activities such as locomotion, but eye velocity records suffer from broad band noise that is not amenable to conventional filtering methods. We evaluated the effectiveness of combined median and moving-average filters by comparing prefiltered and postfiltered records made synchronously with a video eye-tracker and the magnetic search coil technique, which is relatively noise free. Root-mean-square noise was reduced by half, without distorting the eye velocity signal. To illustrate the practical use of this technique, we studied normal subjects and patients with deficient labyrinthine function and compared their ability to hold gaze on a visual target that moved with their heads (cancellation of the vestibulo-ocular reflex). Patients and normal subjects performed similarly during active head rotation but, during locomotion, patients held their eyes more steadily on the visual target than did subjects.

Tracking of illusory target motion: differences between gaze and head responses

We compared ocular and eye-head tracking responses to an illusion of diagonal motion produced when vertical movement of a small visual target was synchronized to horizontal movement of a background display. In response to sinusoidal movement, smooth ocular pursuit followed vertical target motion, with only a small horizontal component. In response to regular stepping movement, all anticipatory saccades were in the direction of the illusion; these erroneous oblique movements were followed by corrective horizontal saccades. When the head was free to move, it usually showed a diagonal trajectory that, for both sinusoidal and stepping target motion, was always in the direction of the illusion; no corrective movements were present. Thus, for our illusory stimuli, eye and head tracking showed qualitative differences that imply that ocular tracking was ultimately controlled by actual target motion but head tracking was controlled by illusory target motion.

Modulation of high-frequency vestibuloocular reflex during visual tracking in humans

1. Humans may visually track a moving object either when they are stationary or in motion. To investigate visual-vestibular interaction during both conditions, we compared horizontal smooth pursuit (SP) and active combined eye-head tracking (CEHT) of a target moving sinusoidally at 0.4 Hz in four normal subjects while the subjects were either stationary or vibrated in yaw at 2.8 Hz. We also measured the visually enhanced vestibuloocular reflex (VVOR) during vibration in yaw at 2.8 Hz over a peak head velocity range of 5-40 degrees/s. 2. We found that the gain of the VVOR at 2.8 Hz increased in all four subjects as peak head velocity increased (P < 0.001), with minimal phase changes, such that mean retinal image slip was held below 5 degrees/s. However, no corresponding modulation in vestibuloocular reflex gain occurred with increasing peak head velocity during a control condition when subjects were rotated in darkness. 3. During both horizontal SP and CEHT, tracking gains were similar, and the mean slip speed of the target's image on the retina was held below 5.5 degrees/s whether subjects were stationary or being vibrated at 2.8 Hz. During both horizontal SP and CEHT of target motion at 0.4 Hz, while subjects were vibrated in yaw, VVOR gain for the 2.8-Hz head rotations was similar to or higher than that achieved during fixation of a stationary target. This is in contrast to the decrease of VVOR gain that is reported while stationary subjects perform CEHT.(ABSTRACT TRUNCATED AT 250 WORDS)

Model for perception of pulsed fluoroscopy image sequences

Pulsed fluoroscopy at reduced frame rates can be used to lower x-ray dose with equivalent detection (hereafter called equivalent perception) of low-contrast, stationary objects. Experimentally average dose savings of 22%, 38%, and 49%, for pulsed fluoroscopy at 15, 10, and 7.5 acquisitions per second, respectively, are documented. Dose savings depend on object size, with fewer savings for smaller objects. To explain these data, we extend the framework of an ideal observer with three models for the spatiotemporal response of the human visual system (HVS). They are model 1, separable; model 2, nonseparable; and model 3, nonseparable with internal observer noise. With no free parameters, model 1 predicts the average dose savings within a 3% difference but does not describe the effect of object size. Models 2 and 3 explain the influence of size, and model 3, with a single free parameter, fits the measurements best. Perception of pulsed fluoroscopy is thus well described in terms of spatiotemporal processing by the HVS.

Perceptual comparison of pulsed and continuous fluoroscopy

Pulsed fluoroscopy (hereafter called pulsed) at reduced acquisition rates, typically 15 acq/s (pulsed-15), is proposed to reduce x-ray dose in interventional procedures. However, since the human visual system (HVS) acts as a temporal low-pass filter that interacts with such acquisitions, the proper dose for pulsed must be obtained in perception experiments. We determine the dose for low-frame-rate pulsed that gives visualization equivalent to that of conventional 30 acq/s fluoroscopy, hereafter called continuous. Computer-generated phantoms are used. They consist of stationary, low-contrast disks on a flat background containing Poisson noise that mimics quantum noise in fluoroscopy. Image sequences are displayed on the video tachistoscope, a device with considerable display flexibility. Three experimental paradigms are used. (1) In a paired-comparison study, pulsed and continuous are displayed side-by-side on the same monitor, and the visibility of a contrast detail phantom is compared. (2) Using this same display, subjects record the minimally detectable disk contrast (the min-contrast measurement). (3) In a four-alternative forced-choice experiment, a disk is placed in one of four positions, and the subject determines the position of the disk. The methods are complementary--the forced-choice experiment properly eliminates the subjectivity of the observer threshold while the paired-comparison study is much more time efficient. With regard to pulsed and continuous comparisons, remarkable similarity is found between the supra-threshold experiments (1 and 2) and the detectability experiment (3); i.e., the average absolute differences in the equivalent-perception dose as determined by the three measures is approximately 3%. No difference is found between interlaced and noninterlaced display. A relatively small dependence of dose savings on disk size is found with larger disks giving increased dose savings. Average dose savings of 22%, 38%, and 49% are found for pulsed-15, pulsed-10, and pulsed-7.5, respectively.

ECG body surface potential mapping many years after successful surgery for coarctation of the aorta

Patients with coarctation of the aorta (CoA) who previously underwent successful surgery are often diagnosed on standard electrocardiograms as having partial right bundle branch block. After surgery 24 patients with CoA had body surface potential mapping (BSPM) with the Case Western Reserve University 180 electrode system; of these 7 had additional aortic stenosis and none had ever had intracardiac communication. The average age at the initial surgery for CoA was 4.0 +/- 3.3 years and at the time of the BSPM it was 12.7 +/- 5.9 years. For the 17 patients with CoA without aortic stenosis the average age at the initial surgery was 5.0 +/- 3.4 years and at the time of the BSPM it was 14.2 +/- 6.0 years. In 11 of the 24 patients, a cardiac catheterization was performed, and each patient demonstrated normal pulmonary artery and right ventricular systolic pressure except for one child with 40 mmHg systolic. In the others all indications were that right ventricular pressure was normal. In 11 of the 24 patients, congestive heart failure had been present in infancy. All 24 cases had evidence for epicardial right ventricular breakthrough on the BSPM, a finding believed to indicate right ventricular activation from endocardium to epicardium via the normal Purkinje system. There were no findings on the BSPM suggesting that right bundle branch block was present. Right ventricular hypertrophy with or without terminal right conduction delay was present on the BSPM in 19 of the 24 patients (9 with additional left ventricular hypertrophy--left ventricular hypertrophy alone in 5). Right ventricular hypertrophy could be considered in 6 of 19 patients in the electrocardiogram, and in 11 of 19 in the vectorcardiogram. The mechanism for the persistent electrocardiographic right ventricular hypertrophy is postulated to involve right ventricular hyperplasia in utero or in early neonatal life, which never disappears.

Experimental tests of a superposition hypothesis to explain the relationship between the vestibuloocular reflex and smooth pursuit during horizontal combined eye-head tracking in humans

1. We used a modeling approach to test the hypothesis that, in humans, the smooth pursuit (SP) system provides the primary signal for cancelling the vestibuloocular reflex (VOR) during combined eye-head tracking (CEHT) of a target moving smoothly in the horizontal plane. Separate models for SP and the VOR were developed. The optimal values of parameters of the two models were calculated using measured responses of four subjects to trials of SP and the visually enhanced VOR. After optimal parameter values were specified, each model generated waveforms that accurately reflected the subjects' responses to SP and vestibular stimuli. The models were then combined into a CEHT model wherein the final eye movement command signal was generated as the linear summation of the signals from the SP and VOR pathways. 2. The SP-VOR superposition hypothesis was tested using two types of CEHT stimuli, both of which involved passive rotation of subjects in a vestibular chair. The first stimulus consisted of a "chair brake" or sudden stop of the subject's head during CEHT; the visual target continued to move. The second stimulus consisted of a sudden change from the visually enhanced VOR to CEHT ("delayed target onset" paradigm); as the vestibular chair rotated past the angular position of the stationary visual stimulus, the latter started to move in synchrony with the chair. Data collected during experiments that employed these stimuli were compared quantitatively with predictions made by the CEHT model. 3. During CEHT, when the chair was suddenly and unexpectedly stopped, the eye promptly began to move in the orbit to track the moving target. Initially, gaze velocity did not completely match target velocity, however; this finally occurred approximately 100 ms after the brake onset. The model did predict the prompt onset of eye-in-orbit motion after the brake, but it did not predict that gaze velocity would initially be only approximately 70% of target velocity. One possible explanation for this discrepancy is that VOR gain can be dynamically modulated and, during sustained CEHT, it may assume a lower value. Consequently, during CEHT, a smaller-amplitude SP signal would be needed to cancel the lower-gain VOR. This reduction of the SP signal could account for the attenuated tracking response observed immediately after the brake. We found evidence for the dynamic modulation of VOR gain by noting differences in responses to the onset and offset of head rotation in trials of the visually enhanced VOR.(ABSTRACT TRUNCATED AT 400 WORDS)

The value of dental radiographic equipment in a Navy field hospital

The portable dental X-ray machine has been used to augment standard field x-ray equipment. This allows for more rapid assessment of combat casualties. The data presented describe the use of the portable dental X-ray machine during the 100-hour ground war against Iraq.

Eye movements during motion after-effect

Using the magnetic search coil technique, we measured torsional eye movements in four male subjects during and after rotation of a visual display around the line of sight. During rotation of the display, subjects developed a torsional nystagmus with slow-phases in the direction of target rotation that had a typical gain of less than 0.01. Upon cessation of display motion, subjects experienced a motion after-effect (MAE) in the direction opposite prior target rotation, which persisted for greater than 15 sec. During this MAE, slow-phase eye movements of low velocity were in the same direction as the MAE, but did not persist as long as perceptual effects. In separate experiments, horizontal eye movements were recorded during horizontal stimulus motion; during MAE, no eye movements occurred due to stronger fixation mechanisms. We conclude that MAE is not caused by retinal slip of images, but MAE and the accompanying eye movements might be produced by shared or similar mechanisms.

Electrocardiographic body surface potential mapping in the Wolff-Parkinson-White syndrome. Noninvasive determination of the ventricular insertion sites of accessory atrioventricular connections

BACKGROUND

A reliable, noninvasive procedure to determine the location of accessory atrioventricular connections in patients with Wolff-Parkinson-White syndrome would add an important diagnostic tool to the clinical armamentarium.

METHODS AND RESULTS

Body surface potential mapping (BSPM) using 180 electrodes in various-sized vests and displayed as a calibrated color map was used to determine the ventricular insertion site of the accessory atrioventricular (AV) connections in 34 patients with Wolff-Parkinson-White syndrome. Attempts were made to determine the 17 ventricular insertion sites described by Guiraudon et al. All 34 patients had an electrophysiologic study (EPS) at cardiac catheterization, and 18 had surgery so the ventricular insertion sites could be accurately located using EPS at surgery. A number of physiologic observations were also made with BSPM.

CONCLUSIONS

The following conclusions were drawn: 1) BSPM using QRS analysis accurately predicts the ventricular insertion site of accessory AV connections in the presence of a delta wave in the electrocardiogram; 2) the ventricular insertion sites of accessory AV connections determined by BSPM and by EPS at surgery were identical or within one mapping site (1.5 cm or less) in all but four of 18 cases; three of the four exceptions had more than one accessory AV connection, and the other had a very broad ventricular insertion; 3) BSPM and EPS locations of the accessory AV connections correlated very well in the 34 cases despite the fact that BSPM determines the ventricular insertion site and EPS determines the atrial insertion site of the accessory AV connection; 4) as suggested by the three cases of multiple accessory AV connections, EPS and BSPM may be complementary since BSPM identified one pathway and EPS identified the other (in the case with a broad ventricular insertion, BSPM and EPS demonstrated different proportions of that insertion); 5) BSPM using ST-T analysis is very much less accurate in predicting the ventricular insertion site of accessory AV connections unless there is marked preexcitation; 6) standard electrocardiography using the Gallagher grid methodology (but with no attempt at stimulating maximal preexcitation) was not as accurate as QRS analysis of BSPM in predicting the ventricular insertion site of the accessory AV connection; however, exact comparison is hampered by the different number and size of the Gallagher and Guiraudon insertion sites; 7) BSPM using QRS analysis appears to be very accurate in predicting right ventricular versus left ventricular posteroseptal accessory AV connections; 8) typical epicardial right ventricular breakthrough, indicative of conduction via the specialized AV conduction system, occurs in all patients with left ventricular free wall accessory AV connections; 9) epicardial right ventricular breakthrough was not observed in cases with right ventricular free wall or anteroseptal accessory AV connections; 10) epicardial right ventricular breakthrough can occur in the presence of posteroseptal accessory AV connections, whether right or left ventricular; and 11) the delay in epicardial right ventricular breakthrough in cases with left ventricular insertion may provide a marker to estimate the degree of ventricular preexcitation.

Multicategory classification of body surface potential maps

A statistical classification method is suggested for body surface potential maps (BSPM). The initial data reduction utilizes the Fourier expansion and time integration, resulting in physiological-oriented features. Based on Fischer's criterion, optimal discriminant vectors are used to map the features to an optimal subdomain. Experimental criteria determine the dimensionality of the subdomain and the number of features to be mapped into it. Classification is performed in two steps. In the first, a k-nearest neighbor (k-NN) rule is used for every two-category problem, the results of which are fed into a voting rule for final classification. The method is tested with 123 patients divided into four categories: normal (NR), ischemia (IS), myocardial infarction (MI), and left bundle branch block (LB) patients. The success is between 88% (for IS) and 100% (for LB) for QRS segment integration. Departure maps were used to explain the misclassified patterns.

QRS onset and offset detection accuracy improvement by additional spatial information in body surface potential maps

A new automatic spatiotemporal algorithm has been developed for detecting QRS onset and offset in body surface potential mapping. The new algorithm, based on a spatial and temporal approach, along with three other algorithms (total energy, 3-lead, and median), was tested in 73 normal and abnormal patients. The reference or gold standard onset and offset times were determined visually by two experienced investigators. The results demonstrate that the new method is less sensitive to noise, to the temporal overlap of the QRS and other components, and to the spatial location changes of QRS initial and final activation. The spatiotemporal method resulted in very consistent findings, with a standard deviation of less than one third of the standard deviation in the next best method.

A cardiac potential mapping system

The technical aspects of a multiple-purpose cardiac mapping system are presented. The authors begin with a brief history of hardware and software development and then concentrate on the major problems in acquiring high-quality recordings from the torso surface or from the epicardial surface and on the processing of the signals for display of color maps or other analysis. To achieve the desired adaptability to a variety of cardiac applications and experiments, they incorporated three parallel microprocessors that can record the signals from 240 electrodes and simultaneously provide display and analysis of the incoming cardiac data. While the parallel processors and modular software offer computational and flexibility advantages, the user interacts with an ordinary AT-compatible computer. This discussion is not a survey of the systems used in the many research laboratories or specific cardiac applications but is focused on experience in developing the specific hardware for such a multi-purpose instrument, and less specifically on the software that makes the system easy to use and adaptable to a variety of experimental and clinical situations.

Stylized chromosome images

Stylized chromosome images 1) serve as a format to test effects of preprocessing algorithms used in automated karyotyping; 2) enhance the ability of humans to perform quantitative analysis of chromosomal aberrations; 3) provide an alternative format for karyotype hard copies produced by automated systems. Stylized chromosomes are two-dimensional computer-generated images based on information extracted from one-dimensional width and density profiles. These profiles correspond to what cytogeneticists observe through the microscope as the shape and banding patterns of stained chromosomes. Stylized presentation sharpens chromosome band boundaries and perimeters, reduces "noise," and enhances gray level variations, which are difficult to distinguish by humans on photographic or computer generated karyotypes. Karyotyping accuracy using stylized images was used to detect difficult areas for automated chromosome identification. Landmark bands sufficient to classify chromosomes were identified; shapes of chromosomes reflected in width profiles were said to aid classification. A two-step automated karyotyping strategy proposed is: 1) classify chromosomes by landmarks, minimum information needed for identification; 2) subsequently employ the full banding pattern with maximum resolution to detect aberrations. Stylized images of abnormal chromosomes have potential for testing hypothesis regarding breakpoints and quantitative analysis, but improvements are needed in homologue normalization and definition of termini of chromosomes.

Pride and purpose as antidotes to black homicidal violence

The incidence of black male homicide is a major public menace. The lowest incidence of black male homicide was when the black power movement was visible and flourishing. Psychohistorical data support the contention that racial pride is an effective means for regulating intragroup tensions. In the absence of an Afrocentric orientation that promotes community power and self-determination, the need for self-reliance is eroded by value illnesses.The value orientation of the black movement supplied the pride used to obtain academic success, to reduce juvenile delinquency, and to help Afro-Americans to structure their lives for personal satisfactions. Blackness has always been about personal power and social control, but society does not allow much access to either for Afro-Americans. As a consequence, stress from racism is severe, asymptomatic, and multi-faceted. The best antidote to black homicidal violence comes from a pro-social effort based upon a self-image that gives a feeling of positive accomplishment and appreciation. Afrocentric pride promotes or enhances pro-social behavior.

The spectrum of right bundle branch block as manifested in electrocardiographic body surface potential maps

A wide spectrum of types of right bundle branch block (RBBB) were studied utilizing the body surface potential maps (BSPMs) of 37 children. Although the spectrum varied from very advanced RBBB to minimal partial RBBB, a common diagnostic feature was the absence of evidence for right ventricular breakthrough in the maps of all patients. Evidence for left ventricular breakthrough was usually seen, the exceptions being five patients with partial RBBB and one of 29 with advanced RBBB. The appearance of evidence for activation of the right ventricle by way of the septum was late in onset. In addition, especially in advanced RBBB, the BSPM pattern reflecting right ventricular activation was prolonged in such a manner that it appeared that utilization of right ventricular Purkinje tissue was minimal and inefficient. The BSPMs during ST-T, which were of inverse polarity, reflect repolarization that is determined by the sequence of depolarization to a greater degree than in the normal. In general, the more extensive the surgery, the more advanced the RBBB (as reflected in the BSPM), although there were exceptions. The one parameter that linked all patients with RBBB together was the absence of evidence for right ventricular epicardial breakthrough.

Cytoprotective effect of prostaglandin E2 in irradiated rat ileum

Radiation injury to the gastrointestinal tract is an infrequent but major clinical problem. Results of previous studies have shown that prostaglandins provide cytoprotection of the gastrointestinal mucosa against a variety of noxious agents, although, prior to this study, the protection against radiation exposure had not been documented. Exteriorized segment of Sprague-Dawley rat ileum was radiated with 10 and 15 Gy (137Cs). One group of rats was pretreated with prostaglandin E2 one hour before and 24 hours after radiation injury. The rats were sacrificed three and five days following radiation injury. Morphometric measurement of mucosal thickness, villous height, crypt of Lieberkühn height and number of mitosis per square millimeter swath of tissue were analyzed. Also, 125IUdR and 3HTdR were injected in a group of rats radiated with 15 Gy (137Cs). 125IUdR counts per minute per milligram of dry weight and 3HTdR labeled cells were counted and analyzed. The morphometric measurements and radioactive labeled tissue counts suggest that prostaglandin E2 has a cytoprotective effect upon irradiated rat ileum. Speculations about the possible mechanism and usefulness of this observation are included.

Electrocardiographic body surface potential maps of the QRS of normal children

Electrocardiographic body surface potential maps (BSPM), utilizing 180 active dry electrodes imbedded in an inflatable vest, were obtained in 40 normal children, ages 8 to 18. The potential levels of the maps are displayed as different colors. A qualitative analysis indicated that the onset of right ventricular breakthrough could always be recognized in the upstroke of the QRS by a pseudopod from a right shoulder minimum extending into an anterior maximum, at an average of 24.4 +/- 4.2 msec., for an average QRS duration of 75.0 +/- 7.1 msec. However there was considerable normal variation, particularly in the mid and late QRS. At the time of depolarization of the free walls of the ventricles, the maximum often remained anterior, with an extension posterior, even through the Frank system vectorcardiogram invariably was posterior. Most remarkable was the terminal QRS of the BSPM, where the terminal maximum may be right superior anterior, anterior superior, or right posterior, presumably reflecting the right ventricular outflow tract, the superior septum, or the posterior basal left ventricle.

Penetrating torso injuries: the role of paracentesis and lavage

Controversy still exists regarding the proper approach to patients with penetrating torso injuries. Mandatory immediate celiotomy and selective observation both have associated risks. Paracentesis with lavage is a rapid, easily performed and readily available technique which can, with a high degree of accuracy, differentiate on initial evaluation those patients with penetrating visceral injuries from those without such injuries. Complications are minimal. The use of these two procedures in evaluating penetrating torso injuries has led to improved patient care and produced major lowering of medical and socioeconomic costs.

Blood lead concentrations of children and dogs from 83 Illinois families

In comparison of blood lead concentrations (BLC) of 119 children and 94 dogs from 83 low-income suburban Illinois families, the mean BLC in the children was 8.9 mug/100 ml greater than that in the dogs. Demonstration of a BLC of diagnostic significance in a family dog increased the probability sixfold of finding a child in the same family with a BLC similarly increased. A history of pica in a family dog also increased the likelihood of finding pica in the family's children. It was concluded that family dogs may be useful sentinels of lead poisoning in children, and that veterinarians seeing dogs in clinical situations may have public health responsibilities with regard to lead poisoning.

Blood lead concentrations in three groups of dogs from a suburban Illinois community

Of 89 clinically normal dogs that were regular patients of a suburban Illinois veterinary hospital, all had blood-lead concentrations (BLC) within the range cited as normal in the literature. In contrast, 22% of 50 dogs from city pound and 15.3% of 98 dogs owned by low-income families of the community had BLC in excess of the normal limits. Additionally, 8% of dogs from the city pound and 4.1% of dogs from low-income families had BLC that are reported to the reliably associated with clinical lead poisoning. Socioeconomic characcteristics of the dog-owning family were more reliably associated with abnormally high BLC than were either history or clinical signs.

Acute drug reactions among the elderly

Research in the field of social gerontology has not examined rug use and abuse amont the aged despite the potential significance of this issue to many students of gerontology. This report, based on an analysis of the records of patients who were treated for acute drug reactions at Jackson Memorial Hospital in Miami, Florida, during 1972, examines characteristics of acute drug reactions among a sample of 60 elderly patients and compares these characteristics with those of other age cohorts. The findings show that acute drug reactions were more likely to occur among whites and females, that a substantial number of the reactions followed the ingestion of two or more substances, that roughly one-third of the admissions were directly related to suicide attempts, and that the vast majority of acute drug reactions among the elderly admissions involved the ingestion of legally manufactured and distributed drugs.