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Biomedical subjects

R R Engel

Publications and source records attributed to R R Engel.

At least 55 records · Page 3Linked to original sources
PubMed1994

Effects of elevated triiodothyronine on cognitive performance and mood in healthy subjects.

The acute effects of experimentally elevated triiodothyronine (T3) serum levels were investigated in 14 healthy male subjects. After oral application of 100 micrograms triiodothyronine on 3 consecutive days a battery of neuropsychological tests and rating scales for mood and bodily complaints were administered. Results show slight mood disturbances but no cognitive impairment caused by T3 level changes. Time intervals were estimated as being longer than in euthyroid state, and word production showed a trend to accelerate. It is concluded that the immediate effects of elevated circulating T3 on cognition and mood are merely discrete. More severe cognitive impairments reported in hyperthyroid patients are probably due to long-term effects on the brain.

Administration, Oral↗
PubMed1994

Verbal memory tests in the differential diagnosis of depression and dementia: discriminative power of seven test variations.

The many tasks for the assessment of verbal memory differ widely in features of presentation and retrieval. In this study, seven common memory tasks (immediate and delayed free recall, randomized presentation, selective reminding, serial recall, recognition after short and long delay) were compared for their discriminative power between depressed, demented, and healthy elderly subjects. Tasks that require little cognitive capacity were hypothesized to be particularly useful to differentiate the patient groups. Demented and depressed patients demonstrated deficits on all tests, the demented being more severe. Only recognition after long and short delay, and delayed recall distinguished demented from depressed patients. Delayed retrieval tasks were more useful to discriminate patient groups than tasks that require little cognitive capacity.

Journal Article↗
PubMed1993

Evaluating modifications in epidemic surveillance systems: a method and an application to AIDS surveillance in Switzerland.

A method is presented for evaluating the impact of a modification in a surveillance system for an epidemic disease among reporting sources susceptible to the modification. The approach requires a control series with reports from sources that are not affected by the modification. The measure of effect is the reporting odds ratio (ROR) which estimates the ratio of reporting proportions (completeness) before and after the change. The proportions themselves remain unknown. Various potential biases are identified and an investigation of one potential bias is proposed. The method may prove useful in supplementing techniques that estimate absolute values of completeness of registry systems. The application to AIDS surveillance data in Switzerland shows that the transition from voluntary to mandatory reporting had an impact that was enhanced by the 1987 revision of the Centers for Disease Control case definition for AIDS. Reporting sources were 1.9 (95% confidence interval [CI]: 1.4-2.6) times more likely to report their patients after introduction of mandatory reporting. It is estimated that 15% of all reports were attributable to mandatory reporting.

Acquired Immunodeficiency Syndrome↗
PubMed1993

The impaired response of spinal cord injured individuals to repeated surface pressure loads.

Three cyclic pressure loads (10 minutes "on" and 5 minutes "off") of 30 or 75 mmHg were applied to the flat anterior surface of the tibia on 11 able bodied (AB) and nine spinal cord injured (SCI) subjects. Transcutaneous PO2 (TcPO2) and PCO2 (TcPCO2), laser Doppler (LD) skin blood flow, velocity, and volume, and the depth of leg indentation (LI) were recorded. In the AB subjects the mean TcPO2 decreased from 31.5 to 27.2 mmHg with the 30 mmHg load. In contrast for the SCI subjects TcPO2 decreased from 32.3 to 7.3 mmHg (significantly differeNt from AB group at p < 0.05). Means of the LD values for volume, velocity, and flow were normalized, giving the highest value of each of the parameters including both the AB and SCI subject during the entire time period a value of 100%. At 30 mmHg loading, the laser LD normalized volume in the AB subjects were 72.5% and 97.0% for the on and off periods, respectively, whereas for the SCI subjects the values were 43.7% and 69.7% for the on and off periods, respectively (significantly different from the AB group at p < 0.05). At 75 mmHg loading, the volume values for the AB subjects were 59.1% and 95.3% for the on and off periods, respectively, whereas for the SCI subjects, the values were 31.6% and 65.4% for the on and off periods, respectively (significantly different from the AB group at p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Factors associated with human immunodeficiency virus seroconversion in homosexual men in three San Francisco cohort studies, 1984-1989.

A total of 83 HIV seroconversions occurred between 1984 and 1989 in three San Francisco cohorts of homosexual and bisexual men. A nested case-control analysis was performed to assess the risk of seroconversion associated with sexual practices. Strong associations were found with total number of intercourse partners and receptive anal intercourse. Weaker, but significant associations were found with receptive oral intercourse. Individuals reporting condom use with some partners were more likely to become infected than those reporting no condom use. Some of this difference was due to increased numbers of sexual partners among those reporting some condom use, but the association remained significant in multivariate analyses. This observation indicates there is some unmeasured risk associated with those using condoms, such as more HIV seropositive partners.

Cohort Studies↗
PubMed1992

Inhibition of glycerol-3-phosphate acyltransferase by analogs of glycerol-3-phosphate.

Analogs of glycerol-3-phosphate were tested as substrates or inhibitors of the glycerol-3-phosphate acyltransferases of mitochondria and microsomes. (rac)-3,4-Dihydroxybutyl-1-phosphonate, (rac)-glyceraldehyde 3-phosphate, (rac)-3-hydroxy-4-oxobutyl-1-phosphonate, (1S,3S)-1,3,4-trihydroxybutyl-1-phosphonate, and (1R,3S)-1,3,4 trihydroxybutyl-1-phosphonate were competitive inhibitors of both mitochondrial and microsomal sn-glycerol-3-phosphate acyltransferase activity. An isosteric analog of dihydroxyacetone phosphate, 4-hydroxy-3-oxobutyl-1-phosphonate, was a much stronger competitive inhibitor of the microsomal than the mitochondrial enzyme. Phenethyl alcohol was a noncompetitive inhibitor of both the microsomal and the mitochondrial acyltransferases. The product of the mitochondrial acyltransferase reaction with (rac)-3,4-dihydroxybutyl-1- phosphonate was almost exclusively (rac)-4-palmitoyloxy-3-hydroxybutyl-1-phosphonate. The microsomal acylation reaction generated both the monoacyl product and (S)-3,4-dipalmitoyloxybutyl-1-phosphonate. The apparent Km for (S)-3,4-dihydroxybutyl-1-phosphonate was 2.50 and 1.38 mM for the mitochondrial and microsomal enzymes, respectively.

Acylation↗
PubMed1992

Double-blind cross-over study of phosphatidylserine vs. placebo in patients with early dementia of the Alzheimer type.

Thirty-three patients with mild primary degenerative dementia according to DSM-III (MMS between 15 and 27) took part in a double-blind cross-over study of phosphatidylserine (Fidia, 300 mg/d) versus placebo. Both treatment phases lasted for 8 weeks with an 8 week washout phase in between and a 4 week washout phase before treatment phase one. Clinical global improvement ratings showed significantly more patients improving under BC-PS than under placebo during treatment phase one. The improvement carried over to the following wash-out and treatment phases. There were no significant improvements in GBS dementia rating scale, psychometric tests or P300-latency. 16-channel EEG mapping findings indicated that the patients initially showed higher power values in all frequency bands (except alpha), when compared to a younger, healthy control group. BC-PS reduced the higher power values compared to placebo, shifting EEG power more towards the normal level.

Aged↗
PubMed1992

Completeness of AIDS reporting in Switzerland: a study based on deaths between December 1987 and June 1990.

OBJECTIVES: To assess completeness and determinants of reporting to the AIDS registry of the Swiss Federal Office of Public Health. DESIGN AND METHODS: Death certificates indicative of AIDS or HIV for deaths occurring between December 1987 and June 1990 were reviewed and compared with reports to the AIDS registry. RESULTS: The completeness of the AIDS registry was 68%. However, almost all cases have now been ascertained, because more than 90% of unreported AIDS cases are detected when death certificates are reviewed. Thus, the ongoing review of death certificates adds to the total case ascertainment. The most important determinant of reporting was the reporting source: specialized AIDS clinics reported 85% of their cases, while all other sources reported only 48%. CONCLUSION: The investigation of the heterogeneity of reporting is important. It can wrongly suggest regional and national differences in the epidemic and lead to a decrease in completeness of reporting over time without actual changes in reporting behavior.

Acquired Immunodeficiency Syndrome↗
PubMed1992

A simple carbon monoxide breath test to estimate erythrocyte turnover.

Carbon monoxide is stoichiometrically released when heme is converted to bilirubin. This report describes and validates a novel technique that permits the estimation of heme turnover and red blood cell survival from the carbon monoxide concentration of end-expiratory breath samples. The end-alveolar Pco of a subject was corrected for environmental carbon monoxide exposure with a simple device that equilibrates with atmospheric carbon monoxide at the same rate as does the subject. The resultant value (endogenous Pco) was tested for its ability to predict heme turnover and red blood cell survival. Red cell survival times of 32 healthy subjects, as calculated from the endogenous Pco, averaged 101 +/- 19 days, a value close to the expected 110-day survival time; 13 patients with clinical evidence of shortened red blood cell survival times had measured erythrocyte life spans ranging from 10 to 59 days. The endogenous Pco of each of seven patients increased after red blood cell transfusion, demonstrating that this technique detected the known rapid turnover of a small fraction of transfused cells. A good correlation (r = 0.91) was observed between heme turnover calculated from endogenous Pco and total fecal biliary pigment output. Carbon monoxide measurements reflect red blood cell destruction in both the marrow and the circulation, therefore yielding shorter life spans than did chromium 51 survival studies. This breath test appears to yield a rapid, semiquantitative assessment of heme turnover and red blood cell survival that is not provided by any other presently available technique. This simple, noninvasive carbon monoxide breath test may find widespread use in the evaluation of anemia and jaundice.

Adult↗
PubMed1991

Fluoxetine versus placebo: a double-blind study with bulimic inpatients undergoing intensive psychotherapy.

In a double-blind trial 40 patients with bulimia nervosa according to DSM III-R criteria were randomly assigned either to a 60 mg fluoxetine group or to a placebo control group. Fluoxetine or placebo was given over a period of 35 days. Parallel to the drug trial, patients participated in an intensive inpatient behavioral psychotherapy program. There were no dropouts at all in the study. Fluoxetine was well tolerated and had only minor adverse effects. In self-ratings and expert ratings concerning attitudes towards eating, eating behavior, and general psychopathology, significant improvements over time were observed in both groups. Using analysis of variance (ANOVA), however, there were no statistically significant "group by time" differences. Results show that the intensive inpatient-care and psychotherapy program was highly effective in changing eating behavior and attitudes as well as general psychopathology. Fluoxetine showed a significant reduction in body weight, especially during the first three weeks of fluoxetine treatment. It was not possible to demonstrate a statistically significant improvement in eating attitudes, eating behavior, and general psychopathology beyond that elicited by intensive inpatient psychotherapy and general inpatient care. These results can possibly be explained by the existence of a "ceiling effect".

Adult↗
PubMed1990

Sensory gating in normals and schizophrenics: a failure to find strong P50 suppression in normals.

In a series of investigations, suppression of the auditory-evoked P50 potential to the second of two paired clicks presented 500 msec apart has been shown to be absent in schizophrenic patients, whereas normals suppress their second response to less than 20% of the first response. The phenomenon has been discussed as a possible trait marker for schizophrenia. The present study with 19 schizophrenics and 23 healthy control subjects was intended as an extended replication of the phenomenon using different stimulus parameters and a slightly different method of measuring P50 amplitudes. Replication was unsuccessful, revealing only weak suppression scores in normal subjects not significantly superior to schizophrenics. Retest sessions yielded generally stronger P50 suppression suggesting that the stability of the measure over time is questionable. The methodological changes are discussed as possible sources of this failure to replicate. It is concluded that the conditions under which P50-suppression occurs should be better clarified in order to facilitate replication.

Acoustic Stimulation↗
PubMed1990

Methodology of 3H-spiperone binding to lymphocytes.

Alterations in lymphocyte binding capacity for the dopamine antagonist 3H-spiperone may be of great interest in psychiatric and neurological disorders: an increase in capacity noted in lymphocytes of schizophrenic patients and their families may well turn out to be a phenotypic vulnerability marker. Since the 3H-spiperone binding assay with lymphocytes does not fulfill common receptor-binding assay criteria and depends more on crucial analytical conditions, shortcomings in binding assay might possibly lead to irreproducible results. A detailed methodological description of the binding assay and subsequent calculations has therefore been given in this paper.

Binding, Competitive↗
PubMed1990

Effects of single doses of alpidem, lorazepam, and placebo on memory and attention in healthy young and elderly volunteers.

The aim of the present study was to compare the effects of alpidem, a new imidazopyridine derivative with benzodiazepine-like anxiolytic effects, with those of lorazepam and placebo on memory and attention in two age groups of healthy volunteers. The study design was that of a randomized double-blind crossover trial with 12 young (18-30 years old) and 12 elderly (65-80) subjects. At weekly intervals, each subject was administered single oral doses of 25 mg alpidem, 50 mg alpidem, 1 mg lorazepam, and placebo in a randomized sequence. Computerized memory and attention tests were performed 90 minutes before and 320 minutes after drug administration. Lorazepam and alpidem 50 mg produced memory impairments: for verbal memory tests the difference against placebo was highly significant for both drugs, while for visual memory this impairment was significant for lorazepam only. No memory effects were seen with 25 mg alpidem. There were no significant drug effects on attention, suggesting a specific amnestic effect not explained by general sedation. Performance of the elderly subjects was much lower than that of the younger ones in both memory and attention tasks. It was not possible to observe any interaction effects between drug and age.

Adolescent↗
PubMed1990

Cognitive determinants of the postimperative negative variation.

This study examined cognitive determinants of the postimperative negative variation (PINV), a slow brain potential observable after the onset of an imperative stimulus in a forewarned reaction time task. Controllability of the aversive imperative stimulus by a motor reaction and predictability of the contingency were varied in a factorial design. The exogenous portion of the slow negative wave was assessed in a passive listening condition using tones of the same quality as the imperative stimuli, but presented without forewarning. Results show that PINV not only occurs when control is absent but also during unpredictably gained control. Similarly, unpredictable lack of control yields a more negative potential than continual helplessness. Negativity elicited by the aversive tone alone was not significantly different from PINV during predictable lack of control. The order of conditions, which was manipulated between groups, did not affect amplitudes. It was concluded that contingency change is a crucial cognitive determinant of the PINV, whereas the effect of lack of control is difficult to differentiate from the sensory influence of the acoustic stimulation.

Adult↗