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E Kaplan

Publications and source records attributed to E Kaplan.

At least 181 records · Page 10Linked to original sources
PubMed1984

The receptive field organization of X-cells in the cat: spatiotemporal coupling and asymmetry.

The visual responses of retinal X-cells, recorded as s-potentials in the lateral geniculate nucleus (LGN), and geniculate X-cells, recorded as action potentials in the LGN, were studied in urethane anesthetized cats. We tested two widely held hypotheses: that the receptive field is (1) separable into spatial and temporal factors, and (2) even symmetric in space. The tests were applied to the amplitudes and phases of responses to sinusoidal gratings which drifted across the receptive field. The X-cell responses failed the test for spatiotemporal separability, and cases of spatial asymmetry were observed. A modified "Difference of gaussians" (mod DOG) model proved useful in the interpretation of the amplitude and phase data. Application of the mod DOG model to the amplitude and phase data revealed the existence of three forms of spatiotemporal coupling. Changes in the temporal frequency of the stimulus can change (1) the ratio between center and surround strengths, (2) the difference between center and surround phases, and (3) the spatial extent of the surround mechanism. Our results led us to a new view of receptive field organization in the X-cell: the center mechanism is spatially homogeneous in its dynamics whereas the surround mechanism is spatially inhomogeneous.

Action Potentials↗
PubMed1984

Phase II study of doxifluridine in advanced squamous cell carcinoma of the head and neck.

We conducted a phase II trial with 5'-deoxy-5-fluoridine (doxifluridine) in advanced squamous cell carcinoma of the head and neck. The drug was given at the dose of 4 g/m2 daily X 5 every 3 weeks. Twenty eligible patients entered this trial, 12 being evaluable for response to doxifluridine. The majority of these patients received previous treatment for cancer. One complete and two partial remissions were observed (25%). Drug-induced toxicity consisted mainly of myelosuppression, mild nausea and vomiting, stomatitis and central nervous system side-effects. Other dosages or schedules for doxifluridine administration might be explored in poor-risk patients.

Aged↗
PubMed1984

Visual-spatial processing in deaf brain-damaged signers.

Sign language displays all the complex linguistic structure found in spoken languages, but conveys its syntax in large part by manipulating spatial relations. This study investigated whether deaf signers who rely on a visual-spatial language nonetheless show a principled cortical separation for language and nonlanguage visual-spatial functioning. Four unilaterally brain-damaged deaf signers, fluent in American Sign Language (ASL) before their strokes, served as subjects. Three had damage to the left hemisphere and one had damage to the right hemisphere. They were administered selected tests of nonlanguage visual-spatial processing. The pattern of performance of the four patients across this series of tests suggests that deaf signers show hemispheric specialization for nonlanguage visual-spatial processing that is similar to hearing speaking individuals. The patients with damage to the left hemisphere, in general, appropriately processed visual-spatial relationships, whereas, in contrast, the patient with damage to the right hemisphere showed consistent and severe visual-spatial impairment. The language behavior of these patients was much the opposite, however. Indeed, the most striking separation between linguistic and nonlanguage visual-spatial functions occurred in the left-hemisphere patient who was most severely aphasic for sign language. Her signing was grossly impaired, yet her visual-spatial capacities across the series of tests were surprisingly normal. These data suggest that the two cerebral hemispheres of congenitally deaf signers can develop separate functional specialization for nonlanguage visual-spatial processing and for language processing, even though sign language is conveyed in large part via visual-spatial manipulation.

Adult↗
PubMed1984

Radionuclide detection of blood-retinal barrier disruption in diabetes mellitus.

Diabetic retinopathy is one of the leading causes of blindness in the United States today. Because early treatment of proliferative retinopathy offers the best chance for visual salvation, there is an essential need for methods of identifying eyes at high risk. Recent research has shown that subclinical leakage from retinal blood vessels is one of the earliest signs of retinopathy. The feasibility of using radionuclide techniques to quantitate blood-retinal barrier disruption is demonstrated by a study in which 23 diabetics and 7 nondiabetics were imaged with an Anger camera in the anterior Waters projection at 2 hours after the administration of Tc-99m DTPA. In the digitized images, regions of interest were placed over each orbit and over one of the cerebral hemispheres. Orbital counts were then compared to cerebral counts on a per pixel basis. Eye to brain ratios were found to be lowest for nondiabetics and highest for patients with proliferative retinopathy. Additionally, the dynamic analysis of the same radiopharmaceutical may allow investigators to further study the pathophysiology of the diabetic eye.

Adult↗
PubMed1984

A comparison of dobutamine infusion and supine bicycle exercise for radionuclide cardiac stress testing.

We have compared the inotropic drug dobutamine to supine bicycle exercise as a means of inducing stress in radionuclide ventriculography studies. Dobutamine has the following properties, making it favorable for widespread usage: 1) ability to be given safely in a peripheral vein, 2) rapid onset, and 3) short duration of action. Each patient underwent supine bicycle progressive resistance testing of 2 minutes per stage followed 30 minutes later by dobutamine administration. Accuracy of diagnosis was 0.93 and sensitivity was 0.89 with dobutamine, while with bicycle the accuracy was 0.93 and sensitivity was 0.94. While not designed to replace supine bicycle testing, incremental infusions of dobutamine appear to be nearly equal in accuracy and sensitivity, providing a satisfactory technique for cardiac evaluation of previously excluded patients.

Catecholamines↗
PubMed1984

Tc-99m PYP localization in calf muscle necrosis.

Tc-99m pyrophosphate (PYP) can localize in an acute myocardial infarct and other extraosseous lesions, including soft tissue necrosis and severe cellular injury A case of Tc-99m PYP uptake in calf muscle necrosis following transfemoral cardiac catheterization is presented. This was incidentally detected on Tc-99m PYP imaging performed for an acute myocardial infarction. Repeat Tc-99m PYP imaging one month later was normal, implying resolution of the ischemic muscle necrosis.

Diphosphates↗
PubMed1984

Sensory nerve action potentials of the medial and lateral plantar nerve.

A simple, reliable method of recording sensory nerve action potentials (SNAP) from the medial and lateral plantar nerves was established using 30 healthy adults as subjects. Potentials were recorded with surface electrodes both antidromically and orthodromically. The mean latency and amplitude of the SNAP of the medial plantar nerve using antidromic stimulation were 2.5msec (+/- 0.32) and 16.3microV (+/- 6.5), respectively. Orthodromically, the latency was 2.5msec (+/- 0.35) and the amplitude 16.5microV (+/- 7.14). For the lateral plantar, antidromically the nerve latency was 2.5msec (+/- 0.35) and the amplitude 14.8microV (+/- 4.41). With the orthodromic procedure, the latency remained unchanged but the amplitude was 11.0microV (+/- 5.59). In the case of the lateral plantar nerve, the antidromic technique consistently resulted in higher amplitude responses.

Adolescent↗
PubMed1984

Nuclear scintigraphy as a diagnostic tool in venous aneurysms.

Aneurysmal dilatation in the low pressure system of internal jugular vein is rare. A case of an aneurysm of the right internal jugular vein, is presented, which was initially diagnosed by nuclear scintigraphy and confirmed by angiography. Clinical presentation, classification, etiology, pathogenesis, and diagnostic modalities of the disease are also reviewed.

Aneurysm↗
PubMed1983

Circadian variation in the urinary excretion of electrolytes and trace elements in men.

Three-hour urine specimens were collected over a period of 27 hours from 11 healthy adult male subjects. Each specimen was analyzed for Na, K, Ca, Mg, and Zn using atomic absorption spectrophotometry. Each sample was also dialyzed, pH 7.35, and subsequently analyzed for Na, K, P, Ca, Mg, Zn, Fe, Pb, Al, Ni, Cu, Mo, Hg, Cr, Cd, and Mn using a multielemental argon-plasma emission system. The data were evaluated on conventional time plots (chronograms) and as computer-determined "cosinor" plots. A population circadian rhythm with a statistical significance was detected for total Na, K, Ca, and Mg, and for nondialyzable Na, K, P, Ca, Zn, and Mo. For almost every element studied the increase from lowest to highest 3-hour group mean along the 24-hour time scale was more than 100%. The 24-hour excretion of Na, K, Ca, Mg, and Zn appeared in good agreement with the so-called "normals." The nondialyzable levels of Fe, Pb, Al, Ni, Cu, Mo, Hg, Cr, Cd, and Mn were similar to the total urinary excretions reported in the literature.

Adult↗
PubMed1983

The use of radionuclide retinal scintigraphy for the assessment of retinopathy in diabetes mellitus.

A computerized radiotracer technique for the detection of loss of retinal vascular integrity secondary to diabetes is presented. Radionuclide retinal scintigraphy with Technetium-99m DTPA was performed on 40 insulin-dependent diabetics and 10 nondiabetics. A ratio of eye to brain activity was used to eliminate errors associated with absolute counting. Ratios were found to be significantly higher in diabetics, especially those with active neovascularization. This technique may prove useful in the assessment and staging of eyes prone to retinopathy.

Adult↗
PubMed1983

Serum theophylline assay by rate nephelometric inhibition immunoassay: a comparison with high-performance liquid chromatography.

The reliability of two clinical laboratory methods for assaying theophylline in serum is compared. Analysis of serum-based standards and 70 patient specimens by rate nephelometric inhibition immunoassay (NIIA) and by high-performance liquid chromatography (HPLC) demonstrates that both methods have comparable random analytical variation. The results indicate that NIIA is a reliable method for measuring serum theophylline and may serve as a practical alternative to the HPLC method.

Chromatography, High Pressure Liquid↗
PubMed1982

Glutathione peroxidase in human cerebrospinal fluid.

Glutathione peroxidase activity was investigated in human cerebrospinal fluid. CSF was obtained from 23 male adult patients with dementia, cerebrovascular disease and multiple sclerosis. The mean glutathione peroxidase activity in the CSF was 6.2 nmol NADPH oxidized min-1 . mg-1 protein +/- 0.6 S.E.M. No differences in the activities were observed in these neurological diseases suggesting that this value may reflect normal glutathione peroxidase activity in human CSF. The age or the protein concentration in CSF did not correlate significantly with glutathione peroxidase activity in CSF.

Adult↗