Biomedical subjects
Publications and source records attributed to D Epstein.
This article discusses the differential diagnosis of abnormal radiographic patterns most commonly seen in emergency department patients with chest disease. Conditions associated with trauma are also described.
The relationship between the amplitude of accommodation and low-luminance myopia was studied in subjects whose ages ranged from 20 to 65. The correlation coefficient values obtained indicate a strong positive correlation between these two factors. The results are discussed in the context of previously-published experimental evidence pointing to accommodation as the primary cause of low-luminance myopia.
Explore the source record for details and available documents.
Thirty-six of 119 patients with myasthenia gravis examined by computed tomography for possible thymic mass had a thymectomy. The computed tomographic findings were compared to the findings of chest x-ray and linear tomography and then correlated with the surgical histopathologic results. Computed tomography detected all cases of thymoma or thymic enlargement due to hyperplasia. Chest x-ray correctly demonstrated 50% of thymomas present while linear tomography demonstrated 88%. Computed tomography was not able to distinguish between enlargement due to thymoma or hyperplasia unless calcification was present. The role of computed tomography is detailed and discussed in relationship to the other diagnostic modalities.
Explore the source record for details and available documents.
Low-luminance myopia of subjects with one normal eye and one aphakic eye was measured with a laser optometer. Low-luminance myopia was registered in the normal eyes, but no such myopia could be found in the aphakic eyes. The same subjects' aphakic eyes were further tested with miotic and dilated pupils. Miosis or mydriasis did not significantly alter the results as compared with measurements obtained with normal pupil size. These results would appear to be the first direct experimental evidence that accommodation is the primary cause of low-luminance myopia.
A right-handed 42-year-old man with bipolar II disorder according to the Research Diagnostic Criteria was tested during two depressive phases, a hypomanic phase, and after a series of left ECT treatments. While drug free he was given a set of tasks sensitive to asymmetry in hemispheric activation. The results indicated hyperactivation of the right hemisphere during the hypomanic episode and of the left hemisphere during the depressive episodes. After left ECT, the patient evidenced greater symmetry. The authors suggest that this case is an instance of reversed lateralization in the regulation of positive and negative mood states.
Every individual exhibits unique perceptual, behavioral, and physiological responses within and across a variety of settings. Despite the idiosyncratic nature of responses, we seek to establish theories that generalize across a large number of individuals. A strict idiographic method intensively examines the response patterns of a small number of individuals, whereas a nomothetic approach focuses on common responses across a large number of individuals. In the present investigation, we seek to learn how individuals perceive and report physical symptoms and sensations. We offer a methodology that capitalizes on the unique physiological responses of individuals but, at the same time, assumes that the underlying perceptual processes relevant to symptom reporting are comparable across individuals. Our approach, then, is both idiographic and nomothetic. As will be discussed, this integrative approach has the potential to be applied to a multitude of behaviors and processes that are of interest to social and personality psychologists.
The technical details of producing an NMR image are briefly explained, followed by a discussion of what relaxation times mean and how tissue properties affect the NMR image. The rest of the article is devoted to the NMR imaging of the thorax.
Night myopia can now be measured accurately with a laser optometer. An increasing number of reports, based on work with this optometer, have supported the hypothesis that night myopia is caused by accommodation. In this study subjects with one phakic and one aphakic eye were tested with respect to the magnitude of night myopia developed in each eye. The results appear to represent the first direct experimental evidence for the hypothesis that accommodation is the primary cause of night myopia.
Iodide uptake by functioning rat thyroid (FRTL) cells is increased by mouse interferon. The effect is detectable using purified interferon; it is not accompanied by an increase in intracellular cyclic AMP levels, is measurable within 20 min, and is prevented by cholera toxin, an agent which inhibits interferon's antiviral activity. The effect of interferon is biphasic with maximally increased iodide uptake (approximately 2-fold) evident at about 300 international mouse units per ml (U/ml) and lesser effects evident at higher concentrations (greater than 1000 U/ml). The effect of mouse interferon on iodide uptake is accompanied by an extremely sensitive antiviral response. Thus, significant antiviral protection is evident at 1 U/ml with FRTL cells, as opposed to 1000 U/ml for nonfunctioning rat thyroid (FRT) cells. Functioning FRTL thyroid cells are also more sensitive to mouse interferon (10-fold) with respect to 2',5'-polyadenylate (An) synthetase activity or to 125I-thyrotropin binding to membrane preparations than are nonfunctioning FRT cells. Antiviral protection in FRTL cells is evident as early as 1 h after exposure to mouse interferon, and is accompanied by a nearly 100-fold increase in the measurable titer of 2'5'-An synthetase activity. Actinomycin D blocks the antiviral effect of interferon, but not its effect on iodide uptake. The results are discussed with respect to the unusually sensitive response of heterologous (rat) cells to mouse interferon: a possible relationship between thyrotropin and interferon receptors; and, the difference in interferon sensitivity exhibited by differentiated (functioning) as opposed to undifferentiated (nonfunctioning) thyroid cells.
This paper has identified nurse practitioners, physician's assistants and, potentially, nurse-midwives, as nonphysician health care providers who might have a significant impact on physician manpower requirements in pediatrics in the United States. These providers are capable of providing well child care, as well as care for minor illnesses. Patient acceptance and the quality of care rendered by these providers appear to be high. Physician acceptance is also high, especially when the physician has actually employed a nonphysician provider. State legislation and reimbursement procedures may interfere with the full utilization of nonphysician providers, but when nurse practitioners and physician assistants are employed in pediatric care, they deliver a wide range of services efficiently and economically. There are estimated to be a total of approximately 5,500 nonphysician providers specializing in pediatric care, but other nonphysician providers who may also care for children are discussed. The total number of these providers for 1980 is estimated at 7,232 and for 1990, at 15,512.
A new instrument was conceived and designed for quantitative measurement of chromophoric areas or colored spots such as are produced in (e.g.) thin-layer chromatography. The areas to be measured are subdivided grid-like into small subunits, and the absorbance of each of these is measured. The sum of absorbances for all subunits is directly proportional to the total amount of light-absorbing substances in a spot. The absorbances of the subunits are measured with a photodetector that contains hundreds of microscopically small photodiodes, arranged in a precise geometric array. The photodiode array is interfaced with a computer via an analog-to-digital converter for numerically integrating the individual signals from each photodiode. With this analytical system, quantitation of light-absorbing substance is accurate and precise for areas of different sizes, shapes, and internal irregularity.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
The modes of action of insulin and of inhibitors of protein synthesis on the degradation of labeled cellular proteins have been studied in cultured hepatoma (HTC) cells. Protein breakdown is accelerated upon the deprivation of serum (normally present in the culture medium), and this enhancement is inhibited by either insulin or cycloheximide. An exception is a limited class of rapidly turning over cellular proteins, the degradation of which is not influenced by insulin or cycloheximide. Alternative hypotheses to explain the relationship of protein synthesis to the regulation of protein breakdown, viz., control by the levels of precursors of protein synthesis, regulation by the state of the ribosome cycle, or requirement for a product of protein synthesis, have been examined. Protein breakdown was not influenced by amino acid deprivation, and measurements of valyl-tRNA levels in HTC cells subjected to various experimental conditions showed no correlation between the levels of charged tRNAVal and the rates of protein degradation. Three different inhibitors of protein synthesis (puromycin, pactamycin, and cycloheximide) suppressed enhanced protein breakdown in a similar fashion. A direct relationship was found between the respective potencies of these drugs to inhibit protein synthesis and to block enhanced protein breakdown. When cycloheximide and insulin were added following a prior incubation of HTC cells in a serum-free medium, protein breakdown was maximally suppressed within 15-30 min. Actinomycin D inhibited protein breakdown only after a time lag of about 90 min. It is suggested that the regulation of protein breakdown in hepatoma cells requires the continuous formation of a product of protein synthesis, in a manner analogous to the mode of the control of this process in bacteria.