Comparative vascular responses in elasmobranchs to different structures of neuropeptide Y and peptide YY.

The vascular responses to neuropeptide Y (NPY) and peptide YY (PYY) were tested in several species of elasmobranchs to assess whether changes in sequence in these neuropeptides from elasmobranchs to mammals are associated with different physiological responses. NPY-like immunoreactivity was detected in the gut and in nerve fibres surrounding some, but not all, blood vessels of six species. Intravenous injection of dogfish, frog and human NPY in anaesthetised fish caused similar vasopressor effects in the three species tested, except human NPY which lowered blood pressure in one of the three. Dogfish NPY and PYY were equipotent pressor agents in two species, but PYY was significantly more potent than NPY in one species. NPY and PYY both contracted isolated gut arteries from three species, but had no effect on isolated efferent arteries tested. In conclusion, differential vascular responses in elasmobranchs are not associated with changes in NPY sequence across vertebrates, but may be with changes in PYY in some species.

Vasoconstrictor effects of galanin and distribution of galanin containing fibres in three species of elasmobranch fish.

Galanin is found in perivascular sympathetic neurons in a wide range of vertebrate species. In placental mammals, galanin has either no effect on blood pressure, or weak depressor effects, but in other vertebrates it has been shown to be a potent pressor agent. To investigate how extensive the vasoconstrictor effects of galanin may be in the vertebrates, the vascular effects of galanin were tested in two species of shark, Heterodontus portusjacksoni, and Hemiscyllium ocellatum, and a ray, Rhinobatos typus. Nerve fibres showing immunoreactivity to galanin were located surrounding gut blood vessels, but were absent from branchial efferent arteries in all three species. Intravenous injection of galanin caused a significant rise in caudal arterial blood pressure in H. portusjacksoni and H. ocellatum, but no change in R. typus. Contraction of segments of pancreatico-mesenteric artery were measured in an organ bath also. Galanin (10(-6) M) caused 21-38% of the maximum K+ induced contraction in all species, but no response in efferent branchial arteries from R. typus. In conclusion, in three elasmobranchs, a galanin-like peptide is present in perivascular nerve fibres, and galanin causes differential vasoconstriction in vascular beds. These data extend the number of vertebrate groups in which galanin has been shown to be a vasoconstrictor peptide.

Characterization and elimination of AC noise in electrocardiograms: a comparison of digital filtering methods.

Diverse digital methods have been advanced previously to remove power line (AC) interference in the ECG. Representative notch filters, adaptive filters and a globally derived filter are surveyed in this study; their performances are compared on artificial signals as well as actual ECGs. The ECGs, recorded at four European medical centers, are from the Common Standards in Electrocardiography (CSE) ECG tape library. AC interference in these ECGs is shown to exhibit two qualities especially relevant to filter design: considerable deviations from a nominal 50 Hz frequency and substantial noise at higher harmonics. Some criteria and useful quantitative measures are suggested to evaluate AC digital filters.

Methodology of ECG interpretation in the AVA program.

The AVA program combines a thirty-year history with an approach that remains innovative; namely: multivariate statistical analysis on orthogonal ECG leads. Its diagnostic reference base includes only diagnoses independently verified by non-ECG criteria. The diagnostic module assesses probabilities of nine alternative disease categories, based on QRS-T parameters; or four other categories in case of conduction defects. Probabilities of left or right atrial overload are also computed. The program also recognizes wall injury, T-wave abnormalities, electrolyte disturbances, myocardial ischemia, and makes differential diagnoses between strain and digitalis effects. An arrhythmia classification module can generate any of 40 rhythm statements. Signal recognition is based on the spatial velocity function. The program has been translated to a microcomputer version.

Optimal lead subsets for reconstruction of QRS and ST-T in 35-lead precordial maps.

Precordial maps have been used for some 15 years to estimate the extent of myocardial injury in patients with acute anterior or lateral wall infarction. Estimates have been based on various QRS- and ST-T-derived parameters, including amplitude sum of ST elevations. Application of the electrodes, commonly 35, is cumbersome and time-consuming with the critically ill. A subset of 5 or 7 selected leads can be applied instead, and the remaining leads calculated from that subset with minimal loss of QRS and ST-T information. Maps were recorded from 100 patients within 72 hours of onset of anterior or lateral infarct. Optimal lead subsets for QRS and ST-T feature extraction were found by the sequential selection method of Lux. Subsets numbering between 2 and 15 leads were derived, with their lead-transform coefficients. Measures to estimate goodness of fit for reconstructed leads included correlations, error-to-signal ratios and root-mean-square errors. These measures were calculated separately over the QRS and ST-T complexes. Reconstructions from a 7-lead subset had a mean 0.92 correlation with ST-T in the original leads and root-mean-square error of only 0.04 mV. Sum of ST elevation differed by only 2% between original leads and reconstructions based on 5 or more leads. To confirm repeatability, lead-transform coefficients were also calculated from a training population of 50 patients and applied to the maps of the other 50.

A computerized data management system for head and neck oncology.

Medical information, diagnostic technology, and modes of therapeutic intervention available for treatment of head and neck cancer have increased exponentially. The concurrent explosion of microcomputer technology has created an ideal instrument for organizing, storing, and reporting the expanded data the head and neck oncologist must now consider. This paper presents the principles, design, and operation of a recently developed head and neck oncological database program (HNODB). Details of implementation on a microcomputer are also described. A historical review of currently used prominent cancer registration programs is presented. It defines the fundamental elements of cancer registration. A review of cancer registration in the United States shows that current systems have various deficiencies and have not kept pace with the evolution of diagnostics, treatments, and computer technologies. The HNODB database program, however, is a valuable model for cancer data management, for it can be applied to small or extensive data collection needs, and it provides an accurate system to identify risk factors, numbers of patients treated and types of treatment given. The program allows for rapid analysis of treatment, results, follow-up, and survival rates of patients with carcinoma of the head and neck.

Estimation and removal of power line interference in the electrocardiogram: a comparison of digital approaches.

Global filtering of AC interference in the digitized ECG is introduced as a new concept. Two different filters embodying a global approach are presented. One is based on a least-squares error fit, the other uses a special summation method. Both methods are compared with a local predictive filter by applying each filter to artificial signals and to real ECGs. A critical evaluation of the results is given.

The orthogonal electrocardiogram as risk indicator for the prediction of myocardial infarction and/or cardiac death.

In a prospective study on Coronary Heart Disease (CHD) orthogonal electrocardiograms (Frank) were recorded annually for ten years from 1,444 asymptomatic, middle-aged males with a mean age of 57.4 +/- 10.6 years. Cases with overt or suspected CHD were excluded. The purpose of the study was to identify risk indicators in electrocardiograms and to compare them with other known risk factors used for prediction of acute CHD events such as myocardial infarction (MI) and/or cardiac death (CD). Such acute events occurred in 88 cases. Pre-event ECGs of these acute events were compared with all others without events, using logistic regression analysis. Identified ECG risk indicators were then compared with other known risk factors such as smoking, blood pressure, cholesterol, age, weight, etc. The predictive power of the ECG, derived mainly from the ST-T complex, exceeded all others by a wide margin. The amplitude of the first 1/8 of the ST-T complex in lead x (similar to V5-V6) together with relative body weight proved best when one pre-event record was available. Prediction improved when ECG changes between two pre-event recordings were included. Precision of measurements by computer appeared essential for improvements in CHD prediction.

Scalar, planar, and spatial measurements of the Frank vectorcardiogram in normal infants and children.

Frank-lead vectorcardiograms (VCGs) were obtained from 1222 normal infants and children. By means of the Pipberger computer system, 176 different scaler and vector measurements obtained from each VCG were correlated with height, weight, race, sex, torso length, chest circumference, and chest diameters to determine the effect of anthropometric indices on the VCG wave forms. Because 5509 tests of statistical significance were performed, correlation coefficients and tests of statistical significance are reported only with p less than 0.001. Height, weight, torso length, and chest circumference show good correlation with QT interval, but these findings are reflective of the decrease in heart rate with age. The VCG does not show consistent correlations with constitutional variables when stratified by age, sex, or race. There were six instances of VCG parameters significantly greater in black children, and four instances of VCG parameters significantly greater in white children. All racial differences, while statistically significant, are small by clinical, hand measurement standards. There were 22 VCG values in boys which exceeded those in girls and only one VCG value in girls which exceeded those in boys. In the pediatric age group, racial differences in VCG wave forms are small and clinically insignificant. The Frank-lead system adequately corrects for constitutional variables in infants and children. Adequate evaluation of pediatric VCGs requires stratification of data according to age and sex.

Estimation and removal of baseline drift in the electrocardiogram.

Estimation procedures for baseline drift have been developed using cubic spline, polynomial, and rational functions. In a test set of 50 electrocardiograms (ECGs), each of 2.5-sec duration, baseline stability was significantly improved by application of any of these methods, except rational function approximation. Amplitude histograms of clinical ECGs after subtraction of estimated baseline distortions showed only small baseline variations over the recording period. For a quantitative validation of the estimation procedures, 10 ECGs with artificial baseline drift were constructed and analyzed by correlation and mean square error calculations. From these comparisons, the polynomial approximation emerged as the most efficient method.

Year-to-year variation of the orthogonal electrocardiogram and vectorcardiogram among 243 normal white males.

When assessing patients' serial ECG changes, the clinician implicitly compares those changes to the limits of change expected in a healthy population. Prospective epidemiological studies, too, develop their criteria from the limits of normal serial ECG changes. Surprisingly then, few studies have reported normal limits for changes between serial ECGs taken six months or longer apart, and all are based on small samples. The present study has a large sample size: 243 white middle-aged and older males, after exclusions for heart disease. Each had at least four consecutive annual examinations with ECGs. Limits of serial variability were computed for 52 measurements. The ECG measurements included durations, amplitudes, ratios, angles and spatial magnitudes. Clinical measurements included blood pressure, cholesterol relative weight and hemoglobin. Year-to-year ECG variabilities were compared to day-to-day variabilities of the same measurements reported earlier. Year-to-year variation was virtually identical to the reported day-to-day variation in most measurements. In only two measurements was year-to-year variation over 25% greater than the reported day-to-day variation.