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Biomedical subjects

A Ohman

Publications and source records attributed to A Ohman.

At least 19 recordsLinked to original sources
PubMed1992

Sequence specific 1H-NMR assignments and secondary structure of a carboxy-terminal functional fragment of apolipoprotein CII.

The structural properties of a synthetic fragment of human apolipoprotein CII (apoCII) has been studied by circular dichroism and proton nuclear magnetic resonance. The fragment corresponds to the carboxy-terminal 30 amino acid residues and retains the ability of apoCII to activate lipoprotein lipase. Like native apoCII, the fragment has a tendency to self-associate in pure aqueous solution. Addition of 1,1,1,3,3,3-hexafluoro-2-isopropanol to aqueous solvent dissolves the aggregates and leads to an increase in the alpha-helical content of the peptide, probably by stabilizing transient helical structures. The resonances in the 1H-NMR spectrum of the fragment in 35% (CF3)2CHOH were assigned through standard procedures from nuclear Overhauser enhancement spectroscopy, correlated spectroscopy and total correlated spectroscopy experiments. The NMR data indicates the formation of a stable alpha helix spanning Ile66-Gly77. Another alpha helical turn may be formed between Lys55 and Ala59 and possibly span even further towards the carboxyl terminus. These structural elements are different from those previously predicted for this part of the sequence of apoCII.

1-Propanol↗
PubMed1992

Symptomatology and electrodermal activity as predictors of neuroleptic response in young male schizophrenic inpatients.

This study examined whether the response to treatment with neuroleptic medication in 21 schizophrenic patients could be predicted from symptomatology, electrodermal activity, and premorbid adjustment. Positive symptoms and high levels of electrodermal activity were associated with a good response to conventional neuroleptic drugs. However, multivariate analysis indicated that symptomatology was the only independent predictor of treatment response.

Administration, Oral↗
PubMed1992

Social interaction, cardiovascular activation and the Type A behavior pattern.

The purpose of the study was to explore the relationship between social interaction and cardiovascular activity during a conflict-inducing communication task in Type A and B subjects. One of the subjects, the leader, was instructed to lead the other subject, the follower, through defined routes on a city map merely by help of instructions. The subjects were facing each other on each side of a screen which allowed eye contact but shielded the maps from view. 40 male students (mean age 24 years) exhibiting Type A or Type B behavior according to the Videotaped Structured Interview participated in the study. The results demonstrated large cardiovascular increases during task performance, particularly for leaders, in systolic blood pressure and heart rate. There were no main effects of Type A vs. Type B, but dyads composed of two Type As showed larger increase in diastolic blood pressure during the conflict phase of the task compared to dyads composed of Type Bs.

Adult↗
PubMed1992

Electrodermal orienting response and central nervous system dopamine and serotonin activity in schizophrenia.

The present study was designed to examine the relationship between electrodermal activity and the levels of the dopamine metabolite homovanillic acid (HVA) and the serotonin metabolite 5-hydroxyindoleacetic acid (5-HIAA) in cerebrospinal fluid. Lumbar cerebrospinal fluid from 36 unmedicated and six medicated schizophrenic patients and 23 controls was analyzed by gas chromatograph-mass spectrometer. The schizophrenic patients and a group of 14 normal controls were presented with a series of orienting tones (1000 Hz, 80 db, 2-second duration) while electrodermal activity was monitored. For the patients, this occurred during an acute episode of schizophrenia. The results suggest an inverse relation between electrodermal activity and the CSF-level of HVA. Although the picture is not entirely consistent, electrodermal nonresponders appear to have normal HVA levels, while electrodermal responders have decreased levels compared with normal controls. There is also a relation between electrodermal activity and 5-HIAA, but this association is not as clear-cut as the one between electrodermal activity and HVA.

Acoustic Stimulation↗
PubMed1991

Electrodermal orienting response, maternal age, and season of birth in schizophrenia.

Consistent with earlier research, male schizophrenic patients born during the season of excess risk for schizophrenia (January-April) showed significantly lower electrodermal responsivity than controls born during the season of excess risk, and patients and controls born during the season not associated with increased risk (May-December). No support for maternal age as an explanation for the season-of-birth effect was found.

Adult↗
PubMed1990

Season of birth and electrodermal unresponsiveness in male schizophrenics.

The present study was designed to examine differences in the electrodermal activity of schizophrenics born in the season of excessive risk (January-April), and those born in the season of nonexcessive risk (May-December). Thirty-two male schizophrenics were presented with a series of orienting tones (1000 Hz, 80dB, 2 sec duration) while electrodermal activity was monitored. They were subdivided according to season of birth and compared in three electrodermal variables, and also in some background and clinical parameters. We found that schizophrenics born in the season of excessive risk were characterized by significantly lower electrodermal activity and more negative symptoms than those born in the season of nonexcessive risk.

Adolescent↗
PubMed1990

Do instructions modify effects of beta-adrenoceptor blockade on anxiety?

To study the interaction between physiological and cognitive factors in anxiety, 44 subjects with public speaking anxiety were allocated to four different groups. Two groups received either beta-adrenoceptor blockade (100 mg of atenolol) or placebo orthogonally crossed with an instruction that heart rate would decrease or an instruction that did not mention cardiovascular effects. During the delivery of a speech, measures of heart rate, systolic and diastolic blood pressures, and self-reported anxiety were obtained. All variables increased during an anticipation period before speech, and heart rate, systolic blood pressure, and self-reported anxiety increased further during speech. Regardless of instructions, atenolol decreased heart rate and systolic blood pressure during both anticipation and speech, whereas no differences were found in self-reported anxiety. This lack of a relationship was seen in spite of the correctly perceived heart rate reduction in the atenolol-treated group receiving an instruction that heart rate would decrease. Cardiac aware subjects, according to the Autonomic Perception Questionnaire, showed higher levels of heart rate and self-reported anxiety at rest than did cardiac unaware subjects. During speech, even though heart rate was similar in atenolol treated groups, self-reported anxiety was higher in cardiac aware than in cardiac unaware subjects. The lack of a relationship between heart rate and self-reported anxiety is discussed in terms of primary and secondary emotions. It is suggested that the perception of external rather than internal cues determines situationally elicited anxiety.

Adult↗
PubMed1989

Electrodermal nonresponding, premorbid adjustment, and symptomatology as predictors of long-term social functioning in schizophrenics.

The hypothesis that electrodermal nonresponsiveness to orienting stimuli delineates a core group of "Kraepelinian" type schizophrenics was tested by following up social functioning outcome over a 2-year period in 37 schizophrenics. Good social functioning outcome required both some self-supporting ability in the job market and a minimal social life. The prior assessments included monitoring of electrodermal responses to a series of moderately intense tones, ratings of reported and observed symptoms during an interview, and ratings of premorbid adjustment on the basis of an interview with a close relative. Electrodermal nonresponding, poor premorbid adjustment, and negative symptomatology predicted poor social functioning during the second follow-up year, but the relationship to nonresponding pertained exclusively to a group of 15 first-episode patients. Discriminant analysis showed that electrodermal nonresponding and symptoms were the only independent predictors of outcome.

Adolescent↗
PubMed1989

Orienting in schizophrenia: habituation to auditory stimuli of constant and varying intensity in patients high and low in skin conductance responsivity.

Groups of schizophrenics and normal controls were exposed to different series of tones of constant (80dB) and variable intensity (60, 80, and 100 dB). Measurements included bilateral skin conductance, finger pulse volume, and heart rate. Both groups were split on the common median in skin conductance response to constant intensity tones to form matched patient and control groups of low and high responsivity. The low and high responsive schizophrenic groups were more clearly separated than the two control groups in rate of spontaneous skin conductance fluctuations, skin conductance magnitudes, and skin conductance levels, primarily because of generalized hyperactivity in high responsive patients. This pattern was clearest for the most intense tone and left hand recordings. High responsive schizophrenics also showed larger response amplitudes, shorter rise and recovery times, and a smaller ratio of elicited to spontaneous responses, than high responsive controls. Finger pulse volume responses recorded from the left hand were smaller in the patient groups, whereas patients and controls did not differ in right hand recordings. High skin conductance responsive subjects showed more heart rate deceleration than low responsive subjects, and schizophrenics had more decelerative responses than controls.

Adult↗
PubMed1989

Components of type A behavior and task-induced cardiovascular activation.

The present study sought to determine whether there are subcomponents of the Type A behavior pattern that are more closely related to cardiovascular reactivity than others. The components studied were factor analytically derived subscales of the Jenkins Activity Survey denoting Irritation and Impatience, on the one hand, and Hard-Driving and Competitive, on the other. Heart rate, pulse transit time, forearm electromyography, and palmar skin conductance were measured while the subjects performed a continuous perceptual motor task, as well as during baselines before and after the task. The Irritation and Impatience dimension was consistently related to task-induced changes in heart rate, both in regression analyses and in extreme group analyses of variance. A significant relation was also observed for pulse transit time but not for electromyography. The Hard-Driving and Competitive dimension, on the other hand, was not related to any psychophysiological measures. These results were interpreted to mean that Irritable and Impatient subjects showed a cardiovascular reaction pattern indicative of active coping processes during task performance.

Adult↗
PubMed1988

Nonconscious control of autonomic responses: a role for Pavlovian conditioning?

This paper reviews data demonstrating nonconscious control of autonomic responses and emotional processes. After briefly having considered theoretical attempts to encompass such processes within Pavlovian conditioning frameworks, it goes on the examine theories and evidence for nonconscious control of emotional processes. The phenomena covered include affective discrimination, neurophysiological mechanisms in the control of conditioned emotional responses, and attentional biases in anxiety disorders. The main section of the paper examines evidence for nonconscious, automatic control of autonomic responses. Such control is demonstrated by data on skin conductance responses to nonattended stimuli, by skin conductance responses in prosopagnosic patients, and by skin conductance responses to masked conditioned stimuli. There are also some data suggesting that responses can be learned to nonconsciously presented in stimuli. In the discussion, it is argued that controlled processing may be dissociated from awareness. That is to say, stimuli may be processed at a controlled level without being accessible for conscious awareness. The relevance of these findings for Pavlovian conditioning is discussed.

Arousal↗
PubMed1987

The personality of the cardiac responder: interaction of seriousmindedness and type A behavior.

Forty healthy university students were recruited from a larger sample to form subgroups of seriousminded and playful Type A and Type B individuals according to their responses to the Telic Dominance Scale and Jenkins Activity Survey. The experiment made use of a factorial design and tested the hypothesis that cardiovascular reactivity during a continuous perceptual motor task is highest in individuals who are characterized by a combination of seriousmindedness and Type A behavior pattern. Relatively low levels of sympathetic reactivity were expected in playful Type B individuals. Heart rate (HR) and pulse transit time (PTT) scores from baseline and task performance periods supported the conclusions that: (1) Cardiovascular activation appeared during task performance; and that (2) seriousmindedness and Type A behavior exerted particularly significant additive effects upon HR, whereas Type A behavior showed a stronger association than did seriousmindedness with PTT scores. Analyses using pre-task score as covariate to task-scores, indicated stronger reactivity for HR in Type A than in Type B subjects.

Achievement↗
PubMed1986

Angular cheilitis: a clinical and microbial study.

The purpose of this prospective study was to re-examine the relative importance of various factors in the pathogenesis of angular cheilitis. Sixty-four patients with cheilitis were examined clinically and microbiologically. In addition, a subsample of 23 patients was examined for serum iron and transferrin. The clinical appearance of the lip lesions fell into 4 categories. A ground rhagad at the corner of the mouth involving adjacent skin, was the most frequent type among dentate patients, whereas among denture wearers a deep lesion following the labial marginal sulcus was frequently observed. Dentate patients and denture wearers with cheilitis often had atopic constitution or cutaneous diseases. Pathogenic microorganisms were cultured from the lesions in all 64 patients; Staphylococcus aureus in 40 patients and Candida albicans in 45. The results of this study indicate a correlation between angular cheilitis and pathogenic microorganisms. Furthermore, among dentate patients, a correlation exists between cutaneous discomfort and angular cheilitis. Other etiological factors suggested for this disorder were found to be of subordinate importance.

Adolescent↗