On physician payment reform.
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Cardiology↗
Biomedical subjects
J Ross
Publications and source records attributed to J Ross.
Prevalence and severity of mitral regurgitation in the mitral valve prolapse syndrome: a Doppler echocardiographic study of 80 patients.
Doppler echocardiography was performed in 80 consecutive patients (22 men, 58 women), aged 38 +/- 16 years, who had mitral valve prolapse diagnosed by two-dimensional echocardiography. Of the 80 patients, 16 (20%) were asymptomatic and 11 (14%) had a normal physical examination (no click or murmur). The M-mode echocardiogram was negative for mitral valve prolapse in 11 patients (14%) and equivocal or nondiagnostic in 19 patients (24%). Mitral regurgitation was evaluated using pulsed mode Doppler echocardiography and was quantified by the mapping technique as minimal or mild when a holosystolic regurgitant jet was recorded just below the mitral valve into the left atrium, and as moderate or severe when the jet was detected at the mid- or distal left atrium. Mitral regurgitation was found in 55 (69%) of the 80 patients and it was minimal or mild in 47 patients (59%) and moderate or severe in 8 (10%). In 20 (36%) of the 55 patients with mitral regurgitation by Doppler technique, a systolic murmur was not detected and each of the 20 had only mild mitral regurgitation. Left atrial and left ventricular size were significantly smaller in patients with mild or no regurgitation as compared with the eight patients with moderate or severe regurgitation. These eight patients were all men (six over 50 years of age) who usually presented with dyspnea and a holosystolic murmur; the mitral valve prolapse was holosystolic by M-mode and involved both leaflets by two-dimensional echocardiography.(ABSTRACT TRUNCATED AT 250 WORDS)
Adolescent↗
Experimental exercise-induced ischemia: drug therapy can eliminate regional dysfunction and oxygen supply-demand imbalance.
The purpose of this study was to test the hypothesis that moderately severe exercise-induced regional myocardial ischemia can be prevented by combined pharmacologic intervention. Eight chronically instrumented dogs were studied using an ameroid constrictor to produce critical stenosis of the left circumflex coronary artery. The dogs were studied during steady state treadmill exercise that induced regional myocardial dysfunction (reduced systolic wall thickening; sonomicrometers) and ischemia (reduced subendocardial blood flow; microspheres). During a control exercise run, wall thickening in the ischemic posterior wall decreased from 21.4 to 13.3% whereas subendocardial blood flow failed to increase normally (36% of that in the normal zone). In the control anterior wall, both wall thickening and subendocardial blood flow increased significantly during the control run. Wall thickness-left ventricular pressure loop areas were calculated as an index of regional work; this index increased abruptly with the onset of exercise in both regions but became significantly depressed in the ischemic region during the steady state exercise. Therapy with a combination of atenolol (0.3 mg/kg body weight orally), diltiazem (0.3 mg/kg intravenously) and isosorbide dinitrate (2.0 mg/kg orally) effectively prevented regional myocardial ischemia and regional dysfunction. After drug therapy, wall thickening in the posterior wall increased from 17.3% at rest to 18.8% during exercise, and the regional transmural blood flow pattern was markedly improved. The initial overshoot of the regional work index during exercise was blunted by the drug therapy, and at steady state no differences between the ischemic and control regions were detected. Thus, combined drug therapy can eliminate exercise-induced regional myocardial ischemic dysfunction and appears to normalize the oxygen supply-demand imbalance.
Adrenergic beta-Antagonists↗
Diastolic mitral regurgitation in patients with atrioventricular conduction abnormalities: a common finding by Doppler echocardiography.
M-mode and Doppler echocardiography were performed in 16 patients with first degree atrioventricular (AV) block, 1 patient with second degree (Wenckebach type) and 3 patients with third degree AV block; 20 individuals with a normal PR interval served as control subjects. The time from the onset of the P wave to the mitral valve closure by M-mode and to the end of mitral flow by Doppler echocardiography were obtained. In 20 normal subjects, the P wave to mitral valve closure interval measured 220 +/- 30 ms by M-mode and to the end of mitral flow 225 +/- 29 ms by Doppler technique (p = NS). In patients with first degree AV block, these intervals measured 242 +/- 41 and 249 +/- 36 ms, respectively (p = NS). Late diastolic (before the onset of the QRS complex) mitral regurgitation was detected by pulsed mode Doppler imaging in 9 (56%) of the 16 patients with first degree AV block but in none with a normal PR interval. In the four patients with advanced AV block, intermittent mid or late diastolic mitral regurgitation was found to depend on the position of the P wave in diastole. With early diastolic P waves, the end of mitral valve flow by Doppler technique occurred 230 to 250 ms after the onset of the P wave and was followed by mild diastolic mitral regurgitation of variable duration. With P waves falling in systole, the mitral valve remained open throughout diastole; during most of diastole, however, there was neither forward mitral flow (diastasis) nor diastolic mitral regurgitation detected by Doppler technique.(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗
Cardiac efficiency and coronary heart disease.
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Coronary Disease↗
A spatial illusion from motion rivalry.
A new dynamic visual illusion is reported: contrast reversal of a horizontal and vertical plaid pattern (produced by adding two orthogonal sinusoidal gratings) causes the pattern to appear as an array of lustrous diamonds, cut by sharp lines into a diagonal lattice structure. On the basis of computer simulations it is suggested that the illusion results from rivalrous interaction of motion detectors tuned to opposing directions of motion.
Humans↗
Adult consumption of alcohol in Victoria, 1967-83.
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Adult↗
Histone mRNA degradation in vivo: the first detectable step occurs at or near the 3' terminus.
The first detectable step in the degradation of human H4 histone mRNA occurs at the 3' terminus in a cell-free mRNA decay system (J. Ross and G. Kobs, J. Mol. Biol. 188:579-593, 1986). Most or all of the remainder of the mRNA is then degraded in a 3'-to-5' direction. The experiments described here were designed to determine whether a similar degradation pathway is followed in whole cells. Two sets of short-lived histone mRNA decay products were detected in logarithmically growing erythroleukemia (K562) cells. These products, designated the -5 and -12 RNAs, were generated by the loss of approximately 4 to 6 and 11 to 13 nucleotides, respectively, from the 3' terminus of histone mRNA. The same decay products were observed after a brief incubation in vitro. They were in low abundance or absent from cells that were not degrading histone mRNA. In contrast, they were readily detectable in cells that degraded the mRNA at an accelerated rate, i.e., in cells cultured with a DNA synthesis inhibitor, either cytosine arabinoside or hydroxyurea. During the initial stages of the decay process, as the 3' terminus of the mRNA was being degraded, the 5'-terminal region remained intact. These results indicate that the first detectable step in human H4 histone mRNA decay occurs at the 3' terminus and that degradation proceeds 3' to 5', both in cells and in cell-free reactions.
Base Sequence↗
Point mutation associated with hereditary persistence of fetal hemoglobin decreases RNA polymerase III transcription upstream of the affected gamma-globin gene.
A base substitution in the 5'-flanking region of a human fetal globin gene is associated with abnormal fetal hemoglobin production. It also reduces by 5- to 10-fold in vitro transcription of the gene by RNA polymerase III. We discuss potential links between polymerase III transcription and abnormal hemoglobin production.
Amanitins↗
Preload reserve and mechanisms of afterload mismatch in normal conscious dog.
Preload reserve and mechanisms of afterload mismatch were examined in 10 normal conscious dogs. The left ventricular (LV) pressure, wall thickness, and external major and minor axis diameters (sonomicrometry) were measured during sinus rhythm, and beat-averaged pressure-volume loops were generated. With maximum angiotensin II infusion, LV end-diastolic volume (EDV) increased by 13 +/- 2% (SEM), LV peak pressure (LVSP) increased by 44 +/- 6%, and stroke volume decreased by 12 +/- 3% (P less than 0.01), demonstrating an apparent descending limb of LV performance. With volume load alone, EDV increased by 9 +/- 2% from control (P less than 0.01), and stroke volume increased by 13 +/- 2%; mean wall stress during ejection was not increased, and heart rate and end-systolic pressure-volume relations showed no changes. To test whether the descending limb of function was due to maximum use of preload reserve or to inadequate venous return, angiotensin infusion was repeated during volume load. The descending limb relating LVEDV to stroke volume was always shifted upward and to the right after volume load, and the stroke volume at a comparable wall stress was 12 +/- 3% higher than during control angiotensin infusion (P less than 0.01). During pressure loading plus volume loading, the maximum EDV increase was 16 +/- 2%, and assuming unchanged afterload and end-systolic volume, an average maximum stroke volume reserve of 31 +/- 4% is calculated. 1) We conclude that sizable preload and stroke volume reserves exist in the normal resting dog; and 2) we describe a mechanism for the descending limb of LV performance curves produced by pressure loading in the intact circulation, which is related to inadequate venous return.
Angiotensin II↗
Exercise-induced regional dysfunction with subcritical coronary stenosis.
The hypothesis was tested that regional myocardial contractile dysfunction can detect subtle regional coronary blood flow maldistribution induced by exercise. In seven dogs, left ventricular pressure (micromanometer), regional systolic wall thickening (WTh, sonomicrometry), and myocardial blood flow (MBF, microspheres) were measured when mild degrees of coronary artery stenosis were produced during treadmill exercise. During exercise without coronary stenosis, WTh increased by 21 +/- 12% (SD), and transmural MBF increased uniformly. In each dog, two levels of coronary stenosis were produced during exercise by adjusting the coronary hydraulic cuff: (1) St-Ex I, where WTh during exercise failed to increase significantly (average change 0 +/- 7%), and (2) St-Ex II, where WTh during exercise decreased moderately from the resting control value (average -20 +/- 8%). In the potentially ischemic zone coronary hyperemia occurred with each run: resting subendocardial MBF was 1.09 +/- 0.30 mg/g/min, and it was 3.04 +/- 0.83 during control exercise, 2.48 +/- 0.75 during St-Ex I, and 1.55 +/- 0.59 ml/g/min during St-Ex II (p less than .01 compared with control exercise and control area). The subendocardial-subepicardial blood flow ratio fell from 1.32 +/- 0.27 during control exercise to 1.07 +/- 0.20 (p less than .05) during St-Ex I, and to 0.64 +/- 0.15 (p less than .01) with St-Ex II. Changes in the subendocardial electrogram and reactive hyperemia occurred more consistently during St-Ex II than St-Ex I. Thus, failure of regional function to increase during exercise detected slight maldistribution of regional MBF, whereas reduction of regional function during exercise of 10% or more below the resting value was a reliable marker of a regional flow defect and was always associated with other evidence of ischemia. Therefore, regional dysfunction during exercise can detect subcritical but functionally significant coronary stenosis, which may allow regional wall motion to be used for detecting coronary artery disease at a relatively early stage.
Animals↗
Myocardial infarction in young patients: an analysis by age subsets.
We examined, in age subsets, 2643 patients with acute myocardial infarction. Clinical features and 1 year morbidity and mortality were compared in 203 young patients (less than 45 years), 1671 patients 46 to 70 years old, and 769 elderly patients (greater than 70 years). Ninety-two percent of young patients were men, and a family history of premature coronary artery disease was more common in young patients (41% compared with 28% of middle-aged and 12% of elderly patients). More young patients were currently smoking cigarettes (82% compared with 56% of middle-aged and 24% of elderly patients), and only 8% of young patients had never smoked. Previous myocardial infarction and history of angina pectoris or congestive heart failure were less common (p less than .001) in the young patients than in middle-aged and elderly patients. In-hospital mortality was only 2.5% for young patients, compared with 9.0% in middle-aged and 21.4% in elderly patients (both p less than .001). Postdischarge 1 year mortality was also strikingly low in young patients, at 2.6% compared with 10.3% in middle-aged and 24.4% in elderly patients. The incidence of reinfarction during the 1 year of follow-up was similar in all subsets. The statistical significance of 65 variables as predictors of 1 year mortality and reinfarction was tested and the following found to be significant (p less than .05): hospital discharge on antiarrhythmic drugs, digoxin, or diuretics; history of previous myocardial infarction or congestive heart failure; chest x-ray findings of heart failure; low ejection fraction; and atrial fibrillation. Thus, young patients entering the hospital have an excellent 1 year prognosis, but those with prior infarction in whom there are selected abnormal findings at hospital discharge comprise a subgroup that may benefit from early aggressive management.
Adult↗
Assessment of ischemic regional myocardial dysfunction and its reversibility.
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Animals↗
Ischemia of the dog heart induces the appearance of a cardiac mRNA coding for a protein with migration characteristics similar to heat-shock/stress protein 71.
Recent evidence indicates that different forms of stress, including hypoxia, can induce specific proteins called heat-shock or stress proteins in various types of mammalian cells. These studies examined whether myocardial ischemia can result in increased levels of proteins with molecular weight and isoelectric point characteristics similar to those described for heat-shock or stress proteins. The left anterior descending coronary artery of the dog heart was completely occluded; normal and ischemic myocardial samples were obtained 6 hours after occlusion; and total cardiac proteins and RNA were prepared. Ribonucleic acid was translated in vitro in a modified rabbit reticulocyte lysate system, and [35S]-methionine-labelled translational products as well as unlabelled cardiac proteins were separated by two-dimensional gel electrophoresis. Total proteins were visualized by silver staining and in vitro translation products quantified by fluorometry. A translatable mRNA coding for a 71,000 dalton peptide with an isoelectric point of 5.8 was markedly increased in the ischemic myocardium after 6 hours of ischemia. A protein with similar migration characteristics was detected in ischemic myocardium but not in normal myocardium. These results indicate that an mRNA coding for a translational product with similar migration characteristics of heat-shock protein 71 is induced by ischemia in the dog heart.
Animals↗
A study of seasonal trace element intakes and hair trace element concentrations in selected households from the Wosera, Papua New Guinea.
The trace element status of nine households from the Wosera subdistrict of Papua New Guinea was assessed. Individual weighed three-day dietary intakes were carried out in April during the hungry season when yams were not eaten and in July when yams were available. Representative staple food items analyzed 'as eaten' for energy, protein, Ca, Mn, Cu and Zn and mean daily energy and nutrient intakes calculated. Hair samples were also collected in July, washed, and analyzed for Zn, Cu and Mn by INAA. Seasonal differences in energy, protein, Ca, Fe and Mn intakes were related to changes in yam consumption. The Zn status of the male (M) and female (F) adults and children (Ch) was sub-optimal based on low median hair Zn levels (microgram/g): -F = 78, n = 8; M = 108, n = 8; Ch2-4yrs = 79, n = 8; Ch5-10yrs = 94, n = 7 and inadequate intakes of readily available Zn (mean + SD): - April M + F = 7.0 + 1.6 mg/day; July M + F = 8.2 + 1.5 mg/day; less than three percent Zn from animal products. In contrast their Mn status, as indicated by elevated median hair Mn levels (microgram/g) (F = 25.1; M = 26.3; Ch2-4yrs = 21.5; Ch5-10yrs = 15.2) was high, attributed to elevated Mn intakes (April M + F = 11.0 + 2.2 mg/day; July M + F = 7.5 + 1.4 mg/day). Median hair Cu levels (microgram/g) (F = 7.6; M = 7.5; Ch2-4yrs = 8.6; Ch5-10yrs = 7.8) and mean Cu intakes (April M + F = 2.2 + 0.4 mg/day; July M + F = 3.0 + 0.6 mg/day) were within the range noted for persons consuming predominantly plant-based diets.
Adult↗
The effect of UV-irradiation on viral infections of the skin.
The effect on the skin of exposure to relatively small doses of ultraviolet light has long been thought beneficial and socially desirable, leading to a 'healthy tan'. However it is less well known that similar (if not smaller) doses of UV-B radiation can have transient but profound depressive effects on the immune response to antigens or pathogens encountered by the skin. The result of this on the immunopathology of both primary and recurrent episodes of persistent viral infections of the epidermis is discussed.
Animals↗
Clinical aspects of adult epiglottitis.
Epiglottitis in adults has been considered a medical rarity. Recent evidence suggests that this disorder is seen in adults regularly, though uncommonly, in clinical practice. We present 14 cases of adult epiglottitis. Most cases were blood culture-negative; Hemophilus influenzae was isolated from blood cultures in two cases and Hemophilus parainfluenzae in one case. There were no deaths. Epiglottitis in adults differs from pediatric epiglottitis in the mode of presentation, bacterial cause and clinical course.
Acute Disease↗
Regional myocardial blood flow and function in experimental myocardial ischemia.
Experiments are reviewed in conscious dogs instrumented with ultrasonic crystals for measuring systolic wall thickening and myocardial blood flow (microsphere technique), and studied under a variety of conditions during acute or chronic circumflex coronary stenosis. With acute progressive stenosis, a nearly linear relation was found between normalized subendocardial flow and function. There were no consistent ST segment changes in the body surface electrocardiogram if wall thickening was less than 25%, although changes occurred in the subendocardial electrogram. The regional flow-function relation was then examined during exercise with various degrees of coronary stenosis; the mean flow-function relation was shifted to the right of the resting relation, but when subendocardial flow was expressed per beat and function normalized as a fraction of that in normal wall the relationship was superimposable upon the resting relation, suggesting that ischemia is absolute (not relative) in the subendocardium during steady state conditions. When the normal increase of wall thickening during exercise was prevented by mild coronary stenosis ischemia could not be clearly detected, but when function during exercise averaged 20% below the resting value, subendocardial blood flow changes and other evidence of ischemia were readily apparent, indicating the sensitivity of wall motion for detecting subcritical coronary stenosis. The regional flow-function relation was also studied in chronic single vessel coronary artery stenosis (ameroid constrictor), in which function was normal at rest (collateral development) but exercise produced large decreases in both regional flow and function. At matched levels of treadmill exercise, a calcium channel blocker (diltiazem) together with beta blockade (atenolol) produced an additive effect that was greater than with either drug alone, with substantial increases in both subendocardial flow and regional function. Finally, studies showing reversible post-reperfusion dysfunction after 15 minutes or two hours of coronary occlusion are reviewed. Partial ischemia for 5-hours, followed by reperfusion also produced regional dysfunction which persisted for at least 3 days but reverted to normal by one week, with little or no histologic damage of the free wall. These studies on regional flow and function during ischemia may carry implications for a number of important clinical phenomena.
Animals↗