Biomedical subjects
Publications and source records attributed to D L Roberts.
Three men working as mouldmakers in the pottery industry acquired a contact allergic dermatitis to a releasing oil. All three were shown to be sensitized to the biocide (1,2-benzisothiazolin-3-one) in the oil.
Three patients with a generalized eruption caused by carbamazepine are described. Two reactions were eczematous, and one was lichenoid in nature. Oral challenge with the drug reproduced the skin disorder in each of these patients. Immunofluorescence microscopy studies demonstrated that in four out of six subjects taking carbamazepine, there were deposits of immunoglobulins in the skin.
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The undoubted clinical usefulness of salicylic acid contrasts markedly with its barely detectable action on normal skin. In this study we have attempted to extend our understanding of the action of salicylic acid by monitoring its effect on the stratum corneum using newly developed techniques for assessing desquamation, as well as using conventional methods for measuring other aspects of epidermal activity. Our findings have succeeded in demonstrating that salicylic acid enhances the shedding of corneocytes and we suggest that this compound in some way decreases corneocyte to corneocyte cohesion. We have confirmed that salicylic acid has no effect on the mitotic activity of the normal epidermis.
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Three hundred patients with ulcerative colitis, 200 with Crohn's disease and matched control subjects completed questionnaires about atopic disease. They were asked whether they had ever suffered from asthma, hay fever, allergic rhinitis or eczema; in ulcerative colitis all of these features occurred with twice the frequency, but in Crohn's disease only eczema was more common than in controls.
A quantitative soil debris isolation method (all debris from known weight of soil plated) and a garden beet seed saprophytic colonization method were compared over a 1-year period for assaying Rhizoctonia solani population. Four fields of different soil textures were selected. Within each field four areas of healthy and four areas of diseases (rhizoctonia root and crown rot) sugarbeets were sampled bimonthly from August 1976 until June 1977. The maximum numbers of R. solani colonies obtained by the debris method were 2 per gram of soil in areas of healthy beets, and 11 per gram of soil in areas of diseased sugarbeets. At such high inoculum densities the beet seed colonization method underestimated R. solani populations, because the inoculum per unit of soil exceeded the numbers of beet seeds per unit of soil available for colonization. Modifications of the beet seed method did not significantly alter results of colonization assays. Ranked correlation comparisons of assay methods yielded r = 0.81 for all data.
Both debris isolation and beet seed colonization methods were used to ascertain Rhizoctonia solani populations in areas of healthy (AH) and rhizoctonia crown rot diseased (DA) sugarbeets within four fields differing in soil texture over a 1-year period (August 1976 to July 1977). Inoculum densities were initially (August-October) higher in DA than in AH, but declined over the winter to levels similar to AH by June. As ascertained by the debris isolation method, AH populations remained low (mostly less than 30 colonies/50 g soil) throughout the year. High (90-422 colonies/50 g soil) DA inoculum densities were apparently sustained by active parasitism. Seasonal R. solani populations were postulated to consist of groupings of propagules differing in capacities for survival. Inoculum densities in AH and DA were similar in June indicating that factors other than inoculum density per se may initiate DA within beet fields. Soil textural differences did not adversely affect R. solani populations. Assays based on debris isolation depicted populations more accurately than did beet seed colonization assays. Most colonies developing in debris isolation plates originated from sclerotia.
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We report a case of miliary tuberculosis with symptoms and signs of an intracranial mass. These were found to be multiple tuberculomas by computerized axial tomography (CT scan). We review the pathophysiologic features of intracranial tuberculomas. The CT scan allows a rapid and sensitive diagnosis of intracranial tuberculosis without utilizing invasive neurodiagnostic techniques. The value of using CT scans following treatment was confirmed.
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The fractions of left anterior descending (LAD) and circumflex (LC) inflow drainage into the canine great cardiac vein (GCV) and coronary sinus (CS) have been quantitated by use of a right heart bypass preparation in which GCV outflow was isolated from the remainder of CS outflow. Following direct LAD injection of indocyanine green dye (ICG), 63 +/- 8% (SD) of the total amount of dye recovered appeared in GCV outflow and the remainder in CS outflow. CS recovery of ICG was decreased appreciably by ligation of epicardial venous connections between the LAD and LC beds, but was not affected by selective reductions of LAD or LC inflow. Only 3 +/- 3% of ICG injected into the LC was recovered in GVC outflow under basal conditions, and these low values were not affected measurably by selective reductions of LAD or LC inflow. CS drainage of LAD inflow could be augmented by selective increments of GCV pressure exceeding 7-10 mmHg. Increments of LC drainage in GCV outflow required CS pressures that exceeded GCV pressures by greater than 10 mmHg.
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A constant current variable frequency pulsed electron capture detector has been incorporated into the gas chromatographic analysis of trace amounts of sulfur hexafluoride (SF6) in water and blood. The resulting system offers a broader effective operating range than more conventional electron capture units and has been utilized for measurements of cardiac output employing constant-rate infusion of dissolved SF6. The SF6 technique has been validated against direct volumetric measurements of cardiac output in a canine right-heart bypass preparation and used subsequently for rapidly repeated measurements in conscious animals and man.
The present review has attempted to summarize the classic symptoms and signs of aortic valve stenosis, especially in an adult. It is emphasized that all the classic signs rarely are present and their absence may mislead an unwary clinician. The diagnostic help provided by noninvasive tests, including echocardiography and phonocardiography, has been emphasized. A need for cardiac catheterization and angiography in most patients prior to corrective surgery is stressed. The natural history of the disease without operative intervention is dim and a significant risk of sudden death exists. The current surgical approach with immediate and long-term results is summarized. Finally, attention has been drawn to the special clinical circumstances when the aortic valve stenosis provides a strinkingly different clinical picture. We cannot find a better way to end this review than by quoting a warning note given by Thomas Lewis in 1920: "It is the faint cry of an anguished and fast failing muscle, which, when it comes, all should strain to hear, for it is not long repeated. A few months, a few years at most, and the end comes."
Pulmonary extravascular volume or lung water (PEV), arterial blood gases, and cardiac hemodynamics were measured in 88 patients with acute myocardial infarction. A progressive increase in PEV and a decrease in arterial oxygen tension (PaO2) were observed from Class I (uncomplicated) patients to Class III (frank pulmonary edema) patients. Heart rate and pulmonary wedge pressure (Pw) rose and cardiac index declined with increasing severity of heart failure by clinical classification. There was a significant correlation between PEV and Pw independent of clinical class (r = 0.47, p less than 0.01). PaO2 had a negative correlation with Pw (r = -0.28, p less than 0.01) as well as PEV (r = -0.26, p less than 0.02). We conclude therefore that increased pulmonary hydrostatic pressure secondary to pulmonary venous hypertension in patients with acute myocardial infarction is a major determinant of interstitial edema. At higher values of PEV, PaO2 was lower. The mechanism of hypoxemia in the presence of excessive lung water may be due to multiple factors, including small airway dysfunction and intrapulmonary shunting.
Study was made of 95 survivors of aortic valve replacement during the early years of this procedure (1964 to 1970). The average follow-up time was 50.2 months. Survival was not related to hemodynamic parameters, such as cardiac index or left ventricular pressure, and did not appear to be influenced by the type of preoperative valve lesion. A history of angina pectoris and a New York Heart Association Class IV grouping were associated with shorter survival. Associated coronary artery disease was a leading cause of death in those patients surviving less than 2 years and angina pectoris the leading cause of morbidity in the long-term survivors. Sudden death occurred in five patients. Once a patient survived 36 months after the operation, the prognosis was excellent.