PubMed Health⌕ Search

Biomedical subjects

D Algom

Publications and source records attributed to D Algom.

At least 37 records · Page 2Linked to original sources
PubMed1987

Perceptual and memorial constructs in children's judgments of quantity: a law of across-representation invariance.

Children at three different ages made judgments of physically presented (perceptual estimation) or symbolically represented (memorial estimation) rectangles. Height and width were integrated according to different, age-dependent algebraic rules. Memorial data obeyed the same integration rules that operated in the original perceptual judgments even when younger children and older children used completely different combination models. Valuation operations were the same in perception and memory for the youngest group (6-year-olds) but became discriminably different at older ages (for the 8- and 10-year olds). Three additional experiments on judgments of volume, liquid quantity, and visual length yielded strong cross-validation support for the general invariance claim (with respect to integration rule theory) but less strong support for the specific invariance claim (with respect to valuation function for the 6-year-old subjects). Results are interpreted as demonstrating lawful and long-enduring ecological constraints on internal representation.

Attention↗
PubMed1987

Pain combines additively across different sensory systems: a further support for the functional theory of pain.

Subjects made magnitude estimations of noxious stimuli produced by a 6 X 6 factorial design of electric shocks (pulse trains) and loud tones. Group data and all individual results conformed to a linear additive model of pain. The estimates of pain approximated the linear sum of the pain estimates of the individual electrocutaneous and auditory components. Pain related differently to the two inducing stimuli. It grew as a mildly expansive power function of current intensity (with an exponent of about 1.2) but as a mildly compressive power function of sound-pressure level (with an exponent of about 0.8). These results replicate recent findings by the same authors in 1986 using a more aversive type of electric stimulation. They are interpreted as supportive of a new functional approach to understand pain and pain-related phenomena.

Humans↗
PubMed1986

Integration of noxious stimulation across separate somatosensory communications systems: a functional theory of pain.

Functional measurement analyses and psychophysical techniques were used to assess how separate, cross-modal, aversive events are integrated in judgements of pain. Subjects made magnitude estimations of noxious stimuli produced by a 6 X 6 factorial design of electric shocks and loud tones. Group data and most of the individual results were consistent with a model of linear pain summation: The estimates of pain approximated the linear sum of the pain estimates of the individual electrocutaneous and auditory components. The relation between painful sensation and current intensity could be described by a mildly expansive power function with an exponent of about 1.1. Auditorily produced painful sensation related to sound pressure level by a mildly compressive power function with an exponent of about 0.90 as a representative figure. Results are interpreted in terms of a functional theory of pain. Noxious events are first transformed to psychological scale values via stimulus-specific psychophysical transfer functions. The outputs of these functions are then combined with other pain-related internal representations of either sensory or cognitive origin, according to simple algebraic models.

Acoustic Stimulation↗
PubMed1985

Integration of stimulus dimensions in perception and memory: composition rules and psychophysical relations.

A series of five experiments used the method of magnitude estimation to assess how height and width are integrated in perceptual and in memorial judgments of area. Separate groups of subjects estimated the areas of perceived or remembered rectangles produced by a symmetrical 4 X 4 factorial design of height and width. Additional independent groups of observers made area judgments, based on special mixes of perceptual and memorial information referring to the height and width components of the to-be-judged rectangles. Both perceptual and memory data obeyed the bilinear interaction prediction of the normative multiplicative model. The relation between perceived and actual area as well as the relation between remembered and actual area could both be described by a compressive power function, with the exponent being reliably smaller for remembered than for perceived area. These results seem to imply a principle of integration rule invariance across perceptual and memorial estimates of a given set of stimuli, in conjunction with characteristically different valuation operations.

Adult↗
PubMed1985

Immune function in blood donors following short-term lymphocytapheresis.

Lymphocyte losses occur during repeat plateletpheresis and/or leukapheresis procedures and are potentially harmful to normal host immune function. This concern prompted us to study the effect of repeat lymphocytapheresis (lymphapheresis) on the immune system of healthy blood donors. Following a total of six lymphapheresis procedures over a 12-day period with removal of a mean of 41.6 X 10(9) lymphocytes, there were no significant changes in donor (n = 5) absolute lymphocyte counts, quantitative immunoglobulin levels or immune response capability as assessed by the following in vitro assays: percent of E, EA, and EAC rosette-forming cells, the percent of surface membrane immunoglobulin bearing cells, and the blastogenic responses to stimulation with phytohemagglutinin, pokeweed mitogen and concanavalin A. The procedures were well-tolerated without complications. During a follow-up period of 18 months, significant increases in total white cell counts (but not absolute lymphocyte counts), and in quantitative immunoglobulin levels (IgG, IgM, and IgA) were observed. The median increases in immunoglobulin levels ranged from 27.5% for IgG to 44% for IgA. We conclude that lymphapheresis as described is relatively safe and our results are reassuring in relation to lymphocyte losses that may occur during repeat cytapheresis procedures of normal blood donors.

Blood Donors↗
PubMed1985

Accuracy of remembering postdelivery pain.

Memory for pain after delivery was assessed by means of a verbal rating scale. 238 young women giving birth to healthy babies as a result of spontaneous delivery were asked to rate intensity of pain immediately following delivery. A day or two later, they were asked to remember how much pain they had experienced immediately after delivery. Analysis showed that the recall of pain was fairly accurate, irrespective of personality type, the level of education, and the number of childbirths. The findings provide some support for the reliability of pain reports from memory for a nonpatient population experiencing a rather unique pain experience.

Adult↗
PubMed1984

Visual velocity input-output functions: the integration of distance and duration onto subjective velocity.

Subjects made magnitude estimations of moving stimuli produced by a 10 X 10 factorial design of distances and durations. Both group and individual data obeyed the bilinear interaction prediction of a simple ratio model. The relation between perceived and actual velocity, as well as the psychophysical contingencies constructed from the marginal means of the design, could be described by a power function with an exponent of about 0.63 as a representative figure. Plotting subjective velocity against physical velocity with either duration or distance as the parameter resulted, respectively, in families of converging psychophysical power functions. Some implications of the results for velocity research, especially the usefulness of specifying the correct metric structure, are discussed.

Adult↗
PubMed1984

Individual differences in loudness processing and loudness scales.

Parameters of the psychophysical function for loudness (a 1000-Hz tone) were assessed for individual subjects in three experiments: (a) binaural loudness summation, (b) temporal loudness summation, and (c) judgments of loudness intervals. The loudness scales that underlay the additive binaural summation closely approximated S. S. Stevens's (1956) sone scale but were nonlinearly related to the scales that underlay the subtractive interval judgments, the latter approximating Garner's (1954) lambda scale. Interindividual differences in temporal summation were unrelated to differences in scaling performance or in binaural summation. Although the exponents of magnitude-estimation functions and the exponents underlying interval judgments varied considerably from subject to subject, exponents computed on the basis of underlying binaural summation varied less. The results suggest that interindividual variation in the exponent of magnitude-estimation functions largely reflects differences in the ways that subjects use numbers to describe loudnesses and that the sensory representations of loudness are fairly uniform, though probably not wholly uniform, among people with normal hearing. The magnitude of individual variation in at least one measure of auditory intensity processing, namely, temporal summation, seems at least as great as the magnitude of the variation in the underlying loudness scale.

Adult↗
PubMed1984

Quantitative and qualitative impairment of immunoregulatory cells in the circulation of rheumatoid arthritic patients.

T cells bearing receptors for the Fc portion of IgM or IgG, TM or TG cells respectively, in the peripheral blood of RA and OA patients were found significantly less often when compared with TM and TG cells in the peripheral blood of normal donors. Using culture combinations of TM, TG and B cells, we were able to demonstrate that the B cells in the peripheral blood of RA patients were constantly of low functional competence and the TMcells varied between highly competent and low competent. RATG cells in general suppressed normal B-lymphoblast differentiation.

Arthritis, Rheumatoid↗
PubMed1981

Ribonuclease activity in renal failure. Evidence for toxicity.

Ribonuclease isolated from human urine is a glucoprotein of molecular weight 33,000. The purified enzyme inhibits: (1) the stimulation of 3H-thymidine uptake into lymphocytes by phytohemagglutinin, pokeweed, and concanavalin A; (2) the growth of pancreatic fibroblastoid cells in in vitro cell culture, and (3) the growth of colonies in bone marrow cell cultures. Ribonuclease levels in the uremic patient vary from 9,500 to 35,000 U/ml (normal 1,041 +/- 247). Serum ribonuclease levels are unaffected by dialytic procedures. It is suggested that the ribonuclease glycoprotein may represent a large number of nondialyzable high molecular weight uremic 'toxins'.

Acute Kidney Injury↗
PubMed1980

Time-related changes in the distribution of sleep stages in brain injured patients.

The correlation between sleep pattern and cognition was studied in a follow-up of 9 patients with traumatic brain injury. The follow-up extended for a mean of 38 weeks after regaining consciousness, with 4-7 study periods for each patient. In addition to sleep pattern, 3 other variables were evaluated: independence in activities of daily living, locomotor and cognitive functions. In 7 patients there was a high correlation (r greater than 0.89) between cognition and REM sleep improvement whereas in 2 patients the correlation was lower (r less than 0.6). It is suggested that in the first group the REM mechanism was intact whereas in the latter, where a brain stem lesion was present, the REM mechanism was damaged. It is also suggested that the sleep pattern recovery time constant depends on the insult to the sleep mechanism structure whereas the REM steady-state recovery process depends on both cognitive maximal capacity and REM neural mechanism integrity.

Adolescent↗
PubMed1980

Temporal sequence discrimination of dichotic tones: the effect of frequency.

The present study was designed to investigate the effect of stimulus frequency on the ability to discriminate the temporal sequence of two 250 ms-duration dichotic stimuli. Dichotic stimulus pairs of three frequencies were tested, 493 Hz, 988 Hz and 3982 Hz, using a three-alternative forced-choice design. The results indicate that frequency does not affect the form, the slope or the location along the abscissa of the discrimination functions. All functions reached 67% discrimination level with a dichotic temporal asymmetry of approximately 40-45 ms.

Auditory Perception↗
PubMed1978

Immunocompetent cells in malignant disease in man. II. Clinical and immunologic correlates in a case of non-Hodgkin's lymphoma.

The immunocompetence of the circulating lymphocytes of a patient with non-Hodgkin's lymphoma was evaluated before, during and after treatment. The immunologic features investigated were (a) the degree of blastogenic transformation induced by phytomitogens (phytohemagglutinin-M, concanavalin A and pokeweed mitogen); (b) the formation of E, EA and EAC rosettes; and (c) antibody-dependent, cell-mediated cytotoxicity. Prior to treatment the subnormal in vitro responsiveness of the cells and the very low concentrations of circulating immunoglobulins suggested immunoincompetence. A gradual shift towards normal in vitro values was observed during treatment, which corresponded to the clinical improvement in the patient's condition.

Chemical Fractionation↗
PubMed1977

Ribonuclease activity in renal failure: evidence for toxicity.

The normal level of serum or plasma poly C-avid ribonuclease activity is 1047 +/- 247 U/mL. Serum levels increase proportionately with elevations in serum creatinine, reaching levels of 9,500-35,000 in patients undergoing dialysis. The levels can be normalised by successful renal transplantation but not by dialysis. Purified human urinary ribonuclease, a glycoprotein enzyme similar to the serum ribonuclease, was capable of: 1) inhibiting the incorporation of 3H-thymidine into mitogen-stimulated lymphocytes; 2) inhibiting the proliferation and growth of bone marrow red cell colonies; and 3) adversely affecting the growth and viability of precursor fat cells.

Cell Division↗
PubMed1976

Immunocompetent cells in man. IV. The inhibition of pokeweed mitogen-induced blastogenesis of normal human peripheral leukocytes by trypsin: a B-cell mitogen of mouse, but not of human, lymphocytes.

Normal human peripheral blood lymphocytes were tested for their blastogenic response in vitro to trypsin. Although it has been shown by other investigators that mouse B lymphocytes are stimulated trypsin to undergo blastogenesis, we have shown that human lymphocytes are not stimulated by trypsin. Paradoxically, trypsin inhibits the response of human lymphocytes to pokeweed mitogen, a B-cell stimulat, without significantly affecting the response of these cells to phytohemagglutinin, a T-cell stimulant. These results serve to underline the functional dissimilarity of mouse spleen cells and human circulating lymphocytes, at least with respect to their blastogenic responses to mitogenic agents.

Animals↗