Canada could learn some health care lessons from Third World, conference told.
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Canada↗
Biomedical subjects
D Faulkner
Publications and source records attributed to D Faulkner.
Age differences in source forgetting: effects on reality monitoring and on eyewitness testimony.
Age differences in memory for the source of memories were investigated using two different experimental paradigms. Experiment 1 used a reality monitoring paradigm. A series of actions were either performed, imagined, or watched, and subjects were later tested for their ability to recognize the actions and identify their origins. Elderly subjects made more false positive responses than did young subjects, and they made more source confusion errors, attributing actions to the wrong sources. Both new and imagined actions were most often misclassified as watched. Experiment 2 used an eyewitness testimony paradigm. After watching a film, subjects read a written version of the story. A recognition test showed that elderly subjects were more often misled by false information in the story than were the younger subjects, and were more confident that their erroneous responses were correct. The findings suggest that a decline in memory for sources may diminish the accuracy of elderly witnesses.
Adult↗
Identification of M1 muscarinic receptors in pulmonary sympathetic nerves in the guinea-pig by use of pirenzepine.
1. The effect of pirenzepine, a muscarinic antagonist considered to be selective for M1 receptors, was studied on bronchoconstriction and bradycardia elicited by preganglionic stimulation of the parasympathetic vagal nerves and by i.v. injections of acetylcholine (ACh) in anaesthetized guinea-pigs. 2. Pirenzepine was equipotent in the heart and lung as an antagonist of the effects of i.v. ACh at postjunctional muscarinic receptors. Doses of pirenzepine in excess of 1 mumol kg-1 abolished all muscarinic responses consistent with non-selective blockade of M3 receptors on airway smooth muscle and M2 receptors on atrial cells. 3. In the lung, low doses of pirenzepine (1-100 nmol kg-1) increased vagally-induced bronchoconstriction despite concurrent partial blockade of the postjunctional receptors. This suggests blockade of neuronal muscarinic receptors. 4. Propranolol (1 mg kg-1) increased control bronchoconstrictor responses elicited by ACh and vagal stimulation but did not alter the potency of pirenzepine for postjunctional receptors in heart or lung. However, pirenzepine-induced enhancement of vagally-induced bronchoconstriction was abolished by propranolol, suggesting that pirenzepine may be an antagonist for muscarinic receptors located in the sympathetic nerves innervating airway smooth muscle. 5. These results confirm that bronchoconstrictor stimuli indirectly initiate activation of an opposing sympathetic reflex in the guinea-pig lung. This response is facilitated by muscarinic receptors located in the sympathetic nervous pathway. 6. The high potency of pirenzepine for the neuronal receptors in the sympathetic nerves suggests that these are M1 receptors. In contrast, the parasympathetic nerves innervating airway smooth muscle in this species contain M2 receptors which inhibit neurotransmission.
Animals↗
Effect of pirenzepine and gallamine on cardiac and pulmonary muscarinic receptors in the rabbit.
1. The effect of muscarinic antagonists considered to be selective for M1 receptors (pirenzepine) and for M2 receptors (gallamine) were studied on bronchoconstriction and bradycardia elicited by stimulation of the vagal nerves and by i.v. acetylcholine (ACh) in anaesthetized rabbits. 2. Pirenzepine was equipotent as an antagonist of ACh-induced responses at postjunctional muscarinic receptors in the heart, lung and blood vessels, whereas gallamine was at least ten times less potent at pulmonary and vascular muscarinic receptors. Thus, gallamine never caused complete inhibition of bronchoconstrictor or hypotensive responses to i.v. ACh, whereas doses of pirenzepine in excess of 1 mumol kg-1 abolished all muscarinic responses. 3. In the lung, both antagonists inhibited bronchoconstriction caused by vagal stimulation and ACh-induced bronchoconstriction to the same extent (pirenzepine, mean ED50 65 +/- 22 and, 130 +/- 28 nmol kg-1 respectively; gallamine, ED50 greater than 10,000 nmol kg-1 for both responses). Enhancement of vagally-induced bronchoconstriction was never observed. 4. In the heart, however, both pirenzepine and gallamine were ten times less potent as antagonists of vagally-induced bradycardia than of ACh-induced bradycardia. This differential blockade was unaltered by propranolol (1 mg kg-1) pretreatment. 5. It is concluded that there is no evidence for M1 or M2 muscarinic receptors in the pulmonary innervation of the rabbit and the potency of the antagonists in abolishing in abolishing vagally-induced bronchoconstriction was consistent with blockade of M3 muscarinic receptors on airway smooth muscle. 6. The results suggest that M2 muscarinic receptors may exert an inhibitory effect on transmission in the parasympathetic nerves innervating the heart in the rabbit. Blockade of such neuronal receptors would increase transmitter output to the atrial cells and explain the low potency of both antagonists in abolishing vagally-induced bradycardia in the rabbit.
Animals↗
Bayesean-deblurred Planar and SPECT nuclear bone imaging for the demonstration of facial anatomy and craniomandibular disorders.
Ambiguities in diagnoses can often be resolved when images from different imaging modalities are compared, and when images are processed with algorithms that improve resolution and contrast. Bayesean deblurring algorithms were developed and applied to Planar and SPECT images of the maxillofacial and temporomandibular joint regions. The combined use of Planar and SPECT imaging with Bayesean deblurring were complementary and provided more diagnostic information than either modality individually. A facial imaging protocol using Planar and SPECT imaging and Bayesean deblurring is described. SPECT maxillofacial anatomy is presented, as well as the application of the imaging protocol of craniomandibular dysfunction. Although not recommended for all patients with craniomandibular disorders, combined use of Planar and SPECT images and Bayesean deblurring techniques appears to be useful in diagnostically difficult or refractory cases.
Adult↗
Emission imaging of patients with craniomandibular dysfunction.
Signs and symptoms of craniomandibular dysfunction in 37 patients were compared with the results of corrected cephalometric tomography and an emission imaging protocol consisting of both planar and single photon emission computed tomography (SPECT) (7500 ZLC Orbiter) images. The planar images and the single photon emission computed tomography projection views were processed with a bayesian deblurring algorithm to improve image quality. The correlation of emission imaging with craniomandibular dysfunction, as indicated by temporomandibular joint pain and joint noise, showed a high sensitivity (93%) and a high specificity (86%), whereas the correlation of corrected cephalometric tomography with temporomandibular joint pain and joint noise showed a relatively high sensitivity (89%) but a low specificity (27%). These results indicate that emission imaging is a sensitive and accurate indicator of craniomandibular dysfunction.
Adult↗
The molecular biology computer research resource.
Described is a new National Institutes of Health supported Molecular Biology Computer Research Resource located at the Dana-Farber Cancer Institute in association with Harvard University, Boston, Massachusetts.
Animals↗
Postganglionic muscarinic inhibitory receptors in pulmonary parasympathetic nerves in the guinea-pig.
The location of neuronal inhibitory muscarinic receptors in pulmonary parasympathetic nerves was investigated in vivo and in vitro. The effects of an agonist for neuronal muscarinic receptors (pilocarpine) and an antagonist (gallamine) were tested on contractions of airway smooth muscle induced by pre- and postganglionic cholinergic nerve stimulation. In anaesthetized guinea-pigs, gallamine potentiated constriction of the tracheal tube and smaller airways induced by preganglionic stimulation. Gallamine also potentiated postganglionic stimulation induced by transmural stimulation of the tracheal tube and by 1-1-dimethyl-4-phenylpiperazinium iodide in the rest of the lung. Bronchoconstriction and contraction of the tracheal tube induced by intravenous acetylcholine were not potentiated by gallamine, indicating that postjunctional muscarinic receptors in airway smooth muscle were not involved in the potentiation. The muscarinic agonist, pilocarpine, had the opposite effect to gallamine and inhibited contractions of the tracheal tube induced by both types of nerve stimulation. In vitro, the inhibitory effect of pilocarpine was demonstrated in the tracheal tube preparation stimulated both pre- and postganglionically. The effect of pilocarpine was antagonized by gallamine. Because gallamine and pilocarpine affected the responses to postganglionic stimulation, the inhibitory muscarinic receptors must be located on the postganglionic neurones of the parasympathetic nerves innervating the trachea and the smaller airways. However, these experiments cannot exclude the possibility that muscarinic receptors may also be located on the soma of the ganglion cells.
Acetylcholine↗
Interaction of "supplementary" scintigraphic indicators of ischemia and stress electrocardiography in the diagnosis of multivessel coronary disease.
Lung uptake, ventricular cavitary dilation and basal myocardial uptake represent abnormalities that have been associated with myocardial ischemia on stress thallium-201 images, but that are supplementary to the conventional assessment of perfusion distribution. These "supplementary" indicators of ischemia were related to the coronary distribution of perfusion abnormalities, the results of electrocardiographic stress testing and to the findings on coronary angiography in 73 patients. Forty patients had multivessel coronary disease; 19 of these had three vessel disease. Perfusion abnormalities were seen in 39 of these 40 patients but were indicative of multivessel coronary disease in only 28 and of three vessel disease in only 6. However, supplementary indicators were present in 33 of 40 patients with multivessel disease and in 15 of 19 with three vessel disease. Furthermore, they were seen in 16 of 22 patients with multivessel disease in whom conventional perfusion abnormalities underestimated the extent of disease, but in only 4 of 12 patients in whom the extent of disease was overestimated. The presence of either perfusion abnormalities in a multivessel distribution or supplementary indicators identified 38 (95%) of 40 patients with multivessel disease. A markedly positive electrocardiographic treadmill test was a less sensitive indicator of multivessel disease, appearing in only 15 of 40 patients. However, it was present in only 4 of 33 patients without multivessel coronary disease and was more specific for that diagnosis than were supplementary scintigraphic indicators (88 versus 67%, p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗
The etiology and implications of dense cavitary "photopenia" on myocardial perfusion scintigraphy.
Dense cavitary "photopenia" was observed on 21 of 200 consecutive stress perfusion scintigrams. A prominent finding in many cases, it sometimes occupied only a portion of the region overlying the ventricular cavity, was often seen in some projections and not others, and was frequently adjacent to myocardial perfusion defects. To distinguish an etiology among reduced cavitary radioactivity, relatively increased background radioactivity, or reduced radioactivity in overlying myocardium, quantitative analysis of cavitary, lung and myocardial radioactivity was performed in patients with dense cavitary "photopenia," with and without lung uptake, and compared with results from studies showing increased lung uptake without cavitary photopenia and with normal studies. The results showed that dense cavitary photopenia was related to reduced radioactivity in overlying myocardium. Correlative imaging studies performed with echocardiography and contrast ventriculography confirmed this relationship to myocardial scar in 15 of 21 patients in whom associated akinesis or dyskinesis was seen. Hence, dense cavitary photopenia on stress perfusion scintigraphy is due to a dense myocardial perfusion abnormality, and is often indicative of related scar and an associated severe contraction abnormality.
Adult↗
Phase image characterization of localized and generalized left ventricular contraction abnormalities.
To evaluate their phase image characteristics, 61 patients with varying left ventricular contraction abnormalities were studied. In 16 normal patients, the left ventricular phase image revealed a homogeneous pattern, a narrow bell-shaped histogram and an orderly spatial progression of phase angle (phi). In 16 patients with segmental abnormalities, the left ventricular phase image showed a region of uniformly delayed phase angle corresponding to the site of segmental abnormality, a discrete secondary histogram peak and a discontinuous, but orderly, spatial progression of phase angle. The mean phase angle (phi) (23.6 +/- 15.7 degrees) and its standard deviation (17.6 +/- 7.2 degrees) differed from the normal group (7.6 +/- 11.1 degrees, p less than 0.002 and 8.9 +/- 2.8 degrees, p less than 0.001). The percent of end-diastolic volume involved in the segmental abnormality, calculated using phase data in 13 of these and in 11 additional patients with a left ventricular aneurysm on ventriculography, correlated well with the percent akinetic segment on scintigraphic (r = 0.78) and angiographic (r = 0.84) study. In 18 patients with generalized abnormalities, the left ventricular phase image revealed multiple regions of inhomogeneous phase angle, a grossly irregular histogram and a disorderly spatial progression of phase angle. The mean phase angle (56.4 +/- 23.9 degrees) and standard deviation (27.3 +/- 7.1 degrees) differed from values in the normal group and from patients with segmental contraction abnormalities (both p less than 0.001). The mean phase angle and its standard deviation in scattered regions with abnormally prolonged phase angle differed significantly from abnormal regions in patients with segmental abnormalities (both p less than 0.001). These patterns of left ventricular phase angle demonstrate characteristics that may help differentiate between ventricles with segmental and generalized contraction abnormalities. Their relation to underlying pathophysiology and potential clinical implications should be considered.
Adult↗
Phase image evaluation of patients with ventricular pre-excitation syndromes.
To localize bypass pathways, left and right ventricular regions were analyzed at rest by phase image analysis in 18 patients with ventricular pre-excitation syndromes. These were compared with image findings in 18 normal subjects. In each of 17 patients with pre-excitation, the site localized on electrophysiologic study correlated closely with the region of earliest ventricular phase angle. This site could be objectively separated from that in normal subjects in each of eight patients with an active left-sided pathway and in both patients with a right-sided pathway. Those with a septal pathway revealed earliest septal phase angle, but could not be separated from normal subjects. In the eight patients with an active left bypass tract, the onset, upstroke and peak of the left ventricular phase histogram preceded those of the right ventricular histogram. Those with a left-sided pathway demonstrated a mean left ventricular phase angle, a difference between mean left and mean right ventricular phase angle and a difference between earliest left and right ventricular phase angles which was significantly less than that in normal subjects (p less than 0.05). These variables presented characteristic converse changes in those with a right-sided pathway. Sequential phase changes in 10 studies suggested "fusion" of normal septal with lateral bypass fronts. Electrocardiographic and electrophysiologic localization of the bypass pathway agreed in only 8 of 14 patients with a recognized delta wave. The phase image represents a new, noninvasive method of evaluating ventricular pre-excitation. The method may provide useful information complementary to that of electrocardiographic and electrophysiologic analysis.
Adolescent↗
A new method with high sensitivity and specificity for localization of abnormal parathyroid glands.
A novel method for localization of abnormal parathyroid glands involving color-processing of nuclear scintigrams of the neck after injection of Thallium-201 and Technetium pertechnetate is presented with surgical correlation. Preoperative localization of single parathyroid adenomas was successful in 88% of previously unoperated patients and in 85.7% of those with adenomas not located at previous surgery. Eighty-three per cent of glands with secondary hyperplasia, 66% of glands with primary hyperplasia, and one carcinoma were localized. No abnormal studies were seen in non-hyperparathyroid hypercalcemia, and no false positive studies were seen. Localization appeared related to larger adenomas (300-5000 mg), although one of 60 mg was localized. Color-comparison dual-isotype scintigraphy was useful for localization of parathyroid adenomas and hyperplastic glands and exceeded the reported sensitivity of either ultrasonography or computerized tomography. It deserves wider evaluation in preoperative management of at least hyperparathyroidism of the primary or persistent types.
Adenoma↗
Age differences in performance on two information-processing tasks: strategy selection and processing efficiency.
Matched groups of old and young adults were compared in two information-processing tasks. In the rotated figures task the participant had to decide whether a figure displayed upright or inverted, faced forwards or backwards, held a ball in its right or left hand. In the sentence verification task the individual had to decide whether an affirmative or negative sentence was true or false as a description of a pattern. From the pattern of reaction times and from the respondents' verbal reports it was possible to identify the strategies used by individuals on each task. The numbers of participants selecting each of the different strategies were similar for old and young groups, but age differences were greater with some strategies than with others. The age difference was minimized when older adults adopted strategies that reduced the amount of processing. The older adults, however, were more disadvantaged when employing strategies that imposed greater processing demands or a heavy memory load.
Adult↗
Word recognition: age differences in contextual facilitation effects.
A series of experiments compared contextual facilitation of word recognition in old (63-80) and young (19-34) subjects. Visual word recognition was examined in a lexical decision task. Sentence contexts or no context preceded words or non-words. Both groups responded faster when context was supplied. For high predictability words, there was no age difference in the magnitude of the contextual facilitation effect. For low predictability words and non-words, the old showed greater contextual facilitation than the young. Auditory word recognition was tested with target words spoken with or without sentence context in a background of white noise. Old subjects, again, showed superior contextual facilitation. It was concluded that old people compensate for deterioration in stimulus quality by more effective use of contextual information.
Adult↗
Submaximal exercise testing after acute myocardial infarction: myocardial scintigraphic and electrocardiographic observations.
The relation between global and regional left ventricular function and electrocardiographic signs of ischemia at rest and during submaximal supine exercise was studied in 27 patients 2 to 3 weeks after acute myocardial infarction. Dynamic myocardial scintigraphy was performed at rest and during submaximal exercise utilizing an in vivo method of labeling red blood cells with technetium-99m pertechnetate. Gated radionuclide blood pool scintigrams were obtained in a modified left anterior oblique, and in some patients also in the right anterior oblique projection, to measure left ventricular ejection fraction and segmental wall motion. Electrocardiographic monitoring of heart rate and rhythm was provided during the exercise. The submaximal exercise test was terminated when the patient's heart rate reached 125 beats/min or if angina, malignant ventricular ectopy or electrocardiographic evidence of myocardial ischemia developed before this rate was reached. The data demonstrate that patients with a recent anterior myocardial infarct, in contrast to patients with a recent inferior or nontransmural infarct, manifest a significant reduction in left ventricular ejection fraction with submaximal exercise. Of the eight patients with an anterior infarct, seven had segmental wall motion abnormalities at rest. Four of these eight manifested more severe abnormalities with submaximal exercise; three had abnormalities at rest that did not change with exercise. Four of the eight had a positive electrocardiographic response during exercise (two were taking digoxin). Of these four, only two had more marked wall motion abnormalities with effort. Of the 13 patients with an inferior infarct, 11 had apparently normal wall motion in the modified left anterior oblique projection at rest, including 2 who manifested segmental wall motion abnormalities with submaximal exercise; the 2 remaining patients had wall motion abnormalities at rest that, on exercise, became more marked in one and were unchanged in one. Four of the 13 had a positive electrocardiographic response with exercise (one was taking digoxin); only one of these had a detectably more severe wall motion abnormality with exercise. Of the six patients with a nontransmural infarct, four had no identifiable wall motion abnormalities at rest; in one of these, an abnormality developed with exercise. The remaining two patients had wall motion abnormalities at rest; in one, a positive electrocardiographic ischemic response developed with exercise. Patients with an anterior infarct appear to have a different functional ventricular response to submaximal exercise at the time of hospital discharge than patients with an inferior or nontransmural infarct. To identify ischemic responses with submaximal exercise in these patients one should ideally use both electrocardiographic monitoring and dynamic myocardial scintigraphy.
Adult↗