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Biomedical subjects

D Friedman

Publications and source records attributed to D Friedman.

At least 163 records · Page 9Linked to original sources
PubMed1990

A developmental study of event-related potentials during explicit and implicit memory.

Event-related potentials (ERPs) were recorded from children, adolescents and adults in response to drawings of common objects or their printed names. Explicit memory was assessed in a continuous recognition paradigm, where each item had (old) or had not (new) been presented earlier. Implicit memory was assessed in separate blocks of pictures and words where item repetition was incidental to the assigned task of identifying stimuli in a given semantic category. Accuracy measures replicated the finding that word memory decays more rapidly than picture memory. A larger anterior negativity to pictures than words in children, but not adolescents or adults, suggested the existence of separate picture/word processing mechanisms that undergo developmental change. ERP repetition effects involved at least two components: a negativity that was larger to new items in both tasks, and a subsequent centroparietal positivity, most likely P3b, that was larger in response to old items for the explicit task only. Both components did not appear to undergo developmental change.

Adolescent↗
PubMed1990

ERPs during continuous recognition memory for words.

Event-related brain potentials (ERPs) were recorded from 10 young adults during a version of the continuous recognition memory paradigm. Words were presented after lags of either 2, 8 or 32 intervening items (equiprobable) following their first presentation, and subjects were required on each trial to make a choice: new (never presented previously) or old (previously presented) response. To assess the effect of probability of new to old items, words were presented in separate blocks with ratios of new to old of 2:1 and 1:1. Reaction time increased and successful recognition decreased systematically as the lag between first and second presentations of an item increased, supporting the distinction between primary (immediate memory) and secondary memory for verbal material. However, there were no systematic effects of item lag on the ERP components. ERPs to new items were characterized by larger N300 and smaller P300 amplitudes (from about 250 to 700 ms) than those to old items. These amplitude differences between old and new ERPs were interpreted as primarily reflecting repetition as opposed to semantic priming effects. These old/new effects did not interact with probability, suggesting that frequency of occurrence is not a major determinant the ERP old/new difference. Old items elicited a late negativity following the behavioral response that was interpreted as due to the presence of a "positive slow wave," with a frontally oriented distribution to new words that was absent in the ERPs to old words. Similarly, subtraction of ERPs elicited by new items that were subsequently unrecognized from those subsequently recognized, showed that underlying the ERP subsequent "memory effect" was a "frontal positive slow wave," dissociable from P300 on the basis of differences in scalp distribution. Since positive slow wave has been interpreted as reflecting "further processing," the data suggest that such processing, possibly similar to elaboration (Graf & Mandler, 1984), enhanced the probability of subsequent recognition.

Adult↗
PubMed1990

Models of integration given multiple sources of information.

Several models of information integration are developed and analyzed within the context of a proto-typical pattern-recognition task. The central concerns are whether the models prescribe maximally efficient (optimal) integration and to what extent the models are psychologically valid. Evaluation, integration, and decision processes are specified for each model. Important features are whether evaluation is noisy, whether integration follows Bayes's theorem, and whether decision consists of a criterion rule or a relative goodness rule. Simulations of the models and predictions of the results by the same models are carried out to provide a measure of identifiability or the extent to which the models can be distinguished from one another. The models are also contrasted against empirical results from tasks with 2 and 4 response alternatives and with graded responses.

Arousal↗
PubMed1990

Five years' experience with Hickman catheters as temporary access for haemodialysis.

Two different types of Hickman catheters were used as central venous access for haemodialysis. The device was implanted in 58 patients with chronic renal failure, already undergoing haemodialysis, because of thrombosis or infection of the previous vascular access, in order to permit immediate treatment and in nine patients with acute renal failure, as a 'first choice' method suitable either for dialysis or for parenteral infusions and nutrition. The catheter was inserted, under local anaesthesia, through the external jugular vein up to the right atrium; the haemodialysis treatment was carried out by single-needle technique 3-4 times weekly and all the catheters were filled daily with heparinised saline and Miconazole solution. The mean duration was 76 +/- 93 days with an overall of 2253 treatments. The flow rate ranged between 150 and 290 ml/min, with acceptable recirculation rate and biochemistry similar to that of standard dialysis. The complication rate was 20%, including thromboses and infections; no operative mortality nor major complications were observed. Based on these data, we believe that the Hickman catheter represents the ideal method of temporary access for haemodialysis.

Adult↗
PubMed1990

Cognitive event-related potential components during continuous recognition memory for pictures.

Event-related brain potentials (ERPs) were recorded from 28 young adult subjects during a continuous recognition memory paradigm, with pictures as stimuli. Subjects were required to determine on each trial if the picture was "new" (never before presented) or "old" (seen previously). To assess differences between primary and secondary memory, old items were presented after lags of 2, 8, and 32 intervening pictures (equiprobable) following their first presentation. The results suggested that a negativity (Cz maximum) at 300 ms was the most likely candidate for the brain event reflecting the retrieval of the item from memory. Old/new effects were modulated by two types of activity, both of which were larger in the ERPs elicited by new items. The earlier of these, possibly similar to the N400, had a duration from about 250-600 ms, began with the N300 deflection, and lasted until "P300" began to decrement. The other was positive, resembled "positive slow wave," onset as P300 began to decrement, and lasted until the end of the recording epoch. There were no consistent effects of item lag on the behavioral data or on any of the ERP components, suggesting that for pictorial stimuli, the distinction between the two types of memory store, primary (i.e., immediate memory) and secondary (newly learned information), may not be relevant. In consonance with the lack of lag effects, it was suggested that the lack of a robust subsequent memory effect on the ERP waveform could have been due to the use of pictures, which may have required less elaborative processing in order to be encoded at input.

Adult↗
PubMed1990

Pictorial essay. Current evaluation of the patient with abnormal visceroatrial situs.

Patients suspected of having derangement of solitus asymmetry should be evaluated individually to determine abdominal visceral and vascular arrangement and to investigate associated problems. This evaluation should begin with plain films to assess cardiac and gastric positions and pulmonary vascularity. Assessment of the bronchial branching patterns should be attempted in all cases. Sonography will delineate the presence or absence of splenic tissue and the anatomy and relationships of the cava and the portal vein. When no spleen is found and the pulmonary vascularity appears congested, a subdiaphragmatic total anomalous pulmonary venous connection should be suspected and verified. If there are splenuli in the retrogastric area, particular attention should be paid to the status of the gallbladder, especially in children who do not have congenital heart disease. Selective spleen scans can confirm the presence of splenic tissue. The high cost and sedation requirement of MR would suggest that it be reserved for cases in which sonography is unable to answer the pertinent questions.

Heart↗
PubMed1990

Psychogenic seizures in children and adolescents: outcome after diagnosis by ictal video and electroencephalographic recording.

Psychogenic seizures in 21 nonepileptic children and adolescents, aged 8 to 18 (mean 14.5) years, were recorded by means of video recording and electroencephalography. The episodes included thrashing movements, limb jerking, or staring, with unresponsiveness. Ictal and interictal electroencephalograms showed no abnormalities after antiepileptic medication was discontinued. Fifteen patients had psychogenic seizures spontaneously during recording, and six had seizures in response to suggestion and intravenous saline injection. After the video-electroencephalographic evaluation, patients and families were told that the episodes were emotional in origin. All patients but 1 agreed to remain without antiepileptic medication, and 16 patients (76%) agreed to begin psychiatric treatment. At 6 to 66 (mean 30) months' follow-up, 14 of 18 (78%) were free of episodes. These data indicate that the majority of young patients with psychogenic seizures have a good outcome. A firm diagnosis is critical so that the episodes can be classified and emphasized as medically not worrisome, permitting a shift away from antiepileptic medication and toward psychiatric treatment.

Adolescent↗
PubMed1989

Use of a holding technique to control the violent behavior of seriously disturbed adolescents.

Therapeutic holding is a treatment technique in which a violent patient is physically contained by people rather than by mechanical or chemical restraints or seclusion. Episodes of therapeutic holding that took place on an inpatient adolescent psychiatric unit over an 18-month period were examined retrospectively through chart review and review of written audits of each episode. During that period, 22.8 percent of the patient population experienced at least one episode of therapeutic holding. Patients requiring this intervention were more likely to be younger and, when day at risk were controlled, to be male and to have had longer stays on the unit. The technique enabled patients to regain behavioral control after a mean of 21.2 minutes, a much shorter period of containment than the four to 16 hours reported in studies of seclusion.

Adolescent↗
PubMed1989

Body composition in subjects with surgically obtained stable body weight normalization.

The body composition of lean control subjects was compared with that of subjects following biliopancreatic diversion for morbid obesity, when their excess weight had been stabilized at under 40 per cent of the ideal body weight value for over two years. Lean body mass, body cell mass and fat were indirectly calculated from total body water and total body sodium, measured by isotope dilution technique. The body composition in the two groups of subjects was essentially normal, as was indicated by the percentage values of the body composition parameters and by the linear correlations between body weight and the lean body compartments size.

Adult↗
PubMed1989

Micronized emulsion for controlled release of physostigmine after oral administration. Part I. Formulation design.

Our aim was to incorporate physostigmine in a fine micronized emulsion delivery system which would prolong drug release following oral administration. Investigation of various types of equipment and experimental conditions led to a fine micronized emulsion of mean droplet size around 1 micron, which was stable at pH 5.5. The effect of physostigmine concentration and salt formation on the interfacial tension and zeta potential of the emulsion was studied. Physostigmine base markedly decreased the interfacial tension as compared to physostigmine hemisulfate and salicylate. Zeta potential was highest in the case of the salicylate. After storage at 4 37 degrees C for four months, the emulsion did not undergo any significant change.

Administration, Oral↗
PubMed1989

Micronized emulsion for controlled release of physostigmine after oral administration. Part II. Release characteristics and pharmacological evaluation.

In vitro release of physostigmine from an emulsion was more prolonged than from a tablet. This prolongation was attributed to the retention capacity of the dispersed oil droplets. Increase of the oily phase volume ratio from 20 to 50% did not substantially decrease the rate of release, and decrease of the mean oil droplet size did not affect the release profile, indicating that the drug was mainly localized in the external phase of the emulsion. The profiles agreed with those predicted from our earlier mathematical equation based on a three compartment model system. In rabbits there were no significant differences in the Tmax and AUC values obtained by use of a tablet and the emulsion form, but the emulsion form elicited less enzyme inhibition. T20 (the therapeutic occupancy time) was markedly extended following use of the emulsion form.

Administration, Oral↗
PubMed1988

Effect of endogenous and synthetic sex steroids on the clearance of antibody-coated cells.

Steroid hormones may influence the clinical expression of immunologic disease; however, their mechanism of action is uncertain. By using an experimental model, we studied the effect of sex steroids on the clearance of antibody-coated cells by macrophages in the spleen and liver. Progesterone significantly inhibited the clearance of IgG-coated E by splenic macrophages, whereas no effect was observed on the clearance of heat-altered E. This effect of progesterone was observed at serum concentrations which are attained during human pregnancy and the menstrual cycle. Furthermore, when splenic macrophages were isolated from progesterone-treated animals, they expressed decreased Fc gamma R activity. In addition, structural analogs of progesterone which have diminished glucocorticoid and progesterone activity retained this effect on macrophage Fc gamma R. In contrast, the estrogens estradiol and estriol as well as a structural estrogen analog with minimal estrogenic activity, 1,3,5(10)-estratrien-3,16 beta-diol, enhanced splenic macrophage Fc gamma R-dependent clearance. This action of estradiol could be partially inhibited by the antiestrogen tamoxifen. However, estradiol did not affect the C3-dependent clearance of IgM-coated E by hepatic macrophages. Concurrent administration of estradiol and progesterone demonstrated that the action of estradiol was predominant. These studies indicate that sex steroids alter splenic macrophage Fc gamma R function in vivo. This result may explain the alteration of disease activity in some human immunologic disorders during changes in hormonal state. Furthermore, analogs of progesterone and estrogen, as well as antiestrogens, which minimally affect the sex organs, retain the ability to alter splenic macrophage Fc gamma R function.

Animals↗
PubMed1988

The prevalence of mitral valve prolapse in patients with Down's syndrome: implications for dental management.

Eighty-three noninstitutionalized patients with Down's syndrome, aged 9 to 55 years, were randomly selected to receive echocardiograms. Forty-one patients had echocardiographic findings indicative of mitral valve prolapse, and 15 of these patients lacked associated auscultatory findings. Because mitral valve prolapse can predispose patients to bacterial endocarditis after bacteremia-producing dental procedures, these findings suggest that if auscultatory findings alone are used, a significant number of patients with Down's syndrome who are at risk for endocarditis may not be currently identified in the course of routine clinical practice.

Adolescent↗
PubMed1988

Auditory event-related potentials in children at risk for schizophrenia: the complete initial sample.

Event-related potentials (ERPs) were recorded from children of schizophrenic parents, children of parents with affective disorders, and children of parents without a history of psychiatric illness. ERPs were elicited during a modification of the "oddball" paradigm, in which two infrequents (a change in pitch and a missing stimulus) were embedded in a series of frequent background events. The data were recorded from electrodes located at midline frontal, central, parietal, and occipital scalp sites. Diagnostic assessments of the parents were performed using the Schedule for Affective Disorders and Schizophrenia-Lifetime Version (SADS-L) and Research Diagnostic Criteria (RDC). Behavioral assessments of the children were made with a modified version (BGAS) of the Global Assessment Scale. ERP amplitudes for several electrophysiological events were compared among groups for target and nontarget stimuli using analyses of of variance of both factor score and baseline to peak measures. No systematic differences suggesting waveform abnormalities in the children of schizophrenic parents (high-risk subjects) were found. However, when the results were analyzed using only those children whose parents had a "pure" diagnosis of either schizophrenia or affective disorder, the children of affectively disordered parents (psychiatric control subjects) showed significantly lower N100 amplitudes (to the frequent event only) than either the normal control or high-risk subjects. No consistent behavioral differences among the three groups emerged. Since only a small percentage of children at risk will eventually develop schizophrenia, ERP amplitude frequency distribution analyses were also performed and compared among groups. However, these did not provide evidence of an outlying subgroup in any of the three groups. There were complex relationships between ERP component amplitudes and behavioral adjustment in adolescence but, in general, these did not distinguish high-risk and psychiatric control subjects from each other. There was no evidence of a relationship between deviant attentional functioning as measured in an earlier round of laboratory testing and ERP late component amplitude.

Adolescent↗
PubMed1988

The Continuous Performance Test, identical pairs version (CPT-IP): I. New findings about sustained attention in normal families.

Thirty families, consisting of two parents and two adolescent children, were tested on a high-processing load Continuous Performance Test, the CPT-IP, which required identification of identical stimulus pairs within a continuously presented series of stimuli. The purpose of this study was to provide normative data for research concerned with the role of attention in psychopathology, especially schizophrenia and major affective disorder. Retest data collected from 23 of the 30 families showed the CPT-IP to be a reliable measure of attention. A major developmental effect was found in capacity to sustain attention to spatial vs. verbal stimuli, which suggested that spatial skills are most developed during childhood and adolescence, while verbal attentional skills tend to peak in adulthood. Factor analysis and family transmission patterns further suggested that the two types of attention (spatial and verbal) were independent and that each was heritable to some degree. Experimental distraction did not disrupt performance in any of the subjects and, in fact, tended to improve it in the adolescents, especially for spatial stimuli. We conclude that the CPT-IP is appropriate for use with families containing members differing widely in age and processing skills.

Adolescent↗
PubMed1988

The specificity of DSM-III schizotypal personality traits.

The rate of DSM-III schizotypal personality traits was evaluated in three groups of adolescent offspring (ages 15-21), defined by the psychiatric diagnosis of their parents. Parental diagnoses included schizophrenic disorder (40 adolescents), affective disorder (35 adolescents), and 'no psychiatric disorder' (normal controls) parents (82 adolescents). The presence of the eight component features of schizotypal personality disorder was assessed from video-taped semistructured psychiatric interviews, subsequently rated by trained psychiatrists, blind to the parental psychiatric status of the subjects. The effect of age, sex, and social class on the pattern of prevalence results was examined. The expected specificity of DSM-III schizotypal personality traits to schizophrenia was not supported by the prevalence pattern of the traits. Rates of 2 or more, 3 or more, and 4 or more schizotypal personality features were highest in the parental psychiatric groups. The rates of schizotypal personality traits in adolescent offspring of affective disorder parents were as high as those previously reported for relatives of schizophrenic disorder probands.

Adolescent↗