Biomedical subjects
Publications and source records attributed to M Guay.
45 older adults were tested twice per year for three years in a 9 (psychomotor) by 30 (health status, well-being) matrix of variables. That only 84 significant correlations were found suggests no relationship between psychomotor performance and health status.
The main purpose of this research was to determine the numeric values of Weber's fraction when subjects were required to estimate temporal durations of 1, 3, 5, 7, and 9 sec. under the method of reproduction. The results provided evidence in support of a constant coefficient of proximity for time estimation of approximately 14.5%.
The purpose of this research was to determine the retroactive interference effects of a single interpolated task (i.e., one temporal duration) on the retention of a criterion duration. This research is of interest because the mnemonic structure of temporal information of different durations is uncertain. Previous research has indicated that there might be a difference in structure for durations of 1 and 4 sec., although the results are inconsistent. Thus, two criterion durations of 1 and 4 sec. and five interpolated durations (i.e., 60%, 80%, 100%, 120%, and 140% of the duration of the criterion) were utilized under the method of reproduction. In addition, subjects were instructed to use either a counting strategy or none (referred to as conscious time estimation) to facilitate the retention of the temporal information. Recall was less variable when using a counting strategy than not and when estimating 1 sec. than 4 sec. However, there was no effect of interpolated activity when comparing performance across different interpolated conditions (no interpolated activity). Apparently, one interpolated duration is not sufficient to produce structural interference with a single criterion duration.
This report describes the use of photolysis and ozonolysis as a means of achieving complete cleavage of the pyridinium ring of (iso)desmosine in crosslinked elastin peptides. Although photolysis leads to the opening of the ring with concomitant formation of lysine, the peptide chains remain attached. Subsequent ozonolysis is able to completely achieve the cleavage of the rest of the ring skeleton, thus leading to the separation of the peptide chains. Formation of new amino acids, i.e. alpha-aminoadipic and glutamic acids, is emphasized. Localization of these amino acids within the released peptides should be of help in structural investigations on the crosslinking zones involving either isodesmosine or desmosine. However, other amino acids such as tyrosine and phenylalanine are sensitive to this procedure and side reactions occur which are responsible for peptide bond cleavage with the formation of breakdown products.
The main purpose of the present research was to investigate the role of self-pacing trial procedures in time estimation. Auditory durations of 1, 4, and 8 sec. were estimated by 12 subjects under the method of reproduction. Different features of performance were investigated using several dependent variables. When left to themselves, subjects chose a relatively short intertrial interval, the duration of which did not differ across the three criterion durations. This finding seemed best explained as an attempt by the subjects to minimize boredom and maximize alertness. Also, subjects waited for a short time before reproducing the criterion duration, and again this period did not differ across the three criterion durations. A significant relationship was found between the duration of the self-paced intertrial interval and self-paced retention interval for all criterion durations. It appeared that subjects were attempting to maximize their time-estimation performance by either minimizing the retention interval or by developing a trial-interval rhythm. Finally, subjects were more variable in their estimates as the criterion duration increased.
The purpose of the present research was to examine proactive interference in general and assimilation effects (i.e., shifts in constant error caused by prior responses) in particular, when subjects used covert counting to aid their retention of the temporal information. Visually presented durations of 1, 4, and 8 sec. were estimated by 18 subjects under the method of reproduction. Three retention intervals (i.e., immediate, 15, and 30 sec.) and three intertrial intervals (i.e., immediate, 15, and 30 sec.) were employed. Analysis of constant error provided no indication that proactive interference was operating in the retention of temporal information as there was no increase in error across trials, no increase in error for longer retention intervals, and no interaction between trials and retention intervals. Also, there was no change in variable error as the retention intervals lengthened for any temporal duration except for the 4-sec. criterion. Finally, the rate of counting (counting units/sec.) was different across the durations to be remembered. The major conclusion of the present research was that counting greatly facilitates retention of temporal information as compared to retention without such a time-aiding strategy.
The main purpose was to examine the role of proactive interference in temporal short-term memory when subjects experienced time under a conscious cognitive strategy for time estimation, made without time-aiding techniques. Visual durations of 1, 4, and 8 sec. were estimated by 18 subjects under the method of reproduction. Three retention intervals were used: immediate reproduction, 15, and 30 sec. of rest. The three intertrial intervals were immediate, 15, and 30 sec. Constant error was used as an index of bias. The constant errors provided no indication that proactive interference was operating in temporal short-term memory. The lack of proactive interference was not associated with intertrial intervals; even when the intertrial intervals were shortened to 1 sec. no proactive interference was observed. Variable error was used to evaluate effects of forgetting. The variable errors for the 4- and 8-sec. durations seemed amenable to a trace-decay explanation.
Nineteen patients with Down's syndrome participated in a double blind study of the clinical effects of pharmacological doses of vitamin B6 administration, starting under 8 weeks of age and continuing until 3 years of age. Ten patients received the vitamin and nine the placebo. In Part 1 of this study, no statistically significant differences were found between the two groups in mental age, height, weight, cranial circumference or tongue protrusion. A study of side effects conducted on a larger open population found vitamin B6 to be relatively safe when administered over long periods of time with photosensitive blisters as the major complication.
This paper describes the combined effects of photolysis and ozonolysis upon the main interchain crosslinks of elastin, desmosine and isodesmosine. Photolysis of purified (iso)desmosines in solution leads to the cleavage of the pyridinium rings to give lysine and an analogue of glutaconic aldehyde which is deformylated to a stable compound absorbing at 242 nm. This photoproduct is subsequently fragmented by ozone into glutamic, alpha-aminoadipic and possibly alpha-amino-delta-oxocaproic acids. However the yields of these different compounds are very low because we observed that numerous competing side reactions (polymerisation, recyclisation) accompany the photoozonolytic decomposition of the pyridinium rings of free (iso)desmosines. The results are clearer when reticulated elastolytic peptides are photoozonolysed. The (iso)desmosines, covalently linked in these peptides, are cleaved into lysine, glutamic and alpha-aminoadipic acids (in a ratio 2:1) with yields corresponding to 80-90% of those expected from the decomposition of the (iso)desmosines originally present in the peptide fraction. We have also observed that ozonolysis alone degraded another crosslink present in these peptides, the aldol condensation product, resulting in the production again of glutamic and alpha-aminoadipic acids in amounts consistent with the known concentrations of this particular crosslink in elastin. Finally we noted that the complete photoozonolytic degradation of the (iso)desmosines present in a semi purified reticulated elastolytic fraction resulted in a shift of the size distribution of these peptides toward lower values. It is not certain however that this shift, indicative of a freeing of the polypeptide chains from their original three dimensional network, is due uniquely to the cleavage of the (iso)desmosines. Indeed we have observed that tyrosine and phenylalanine were also degraded during photoozonolysis. Not knowing the mechanism of this degradation it is impossible to rule out the possibility that concomitant cleavages of peptide bonds did occur.
Explore the source record for details and available documents.
Foeto-placental anasarca was diagnosed at 34 weeks gestation in a patient with acute hydramnios. Foetal tachycardia at 300 bpm was recorded. This obstetrical problem led to the birth of a premature baby with generalised oedema, for which the only apparent cause was the tachycardia. This was identified as a paroxysmal junctional reciprocating tachycardia, initiating on atrial extrasystolic echos, terminating on R waves, with lengthening of the PR interval at the onset of tachycardia, without acceleration of the sinus rate and P'R = RP'. Paroxysmal junctional reciprocating tachycardia in utero was responsible for congestive cardiac failure and foeto-placental anasarca. The cardiac failure was treated by foetal delivery, artificial respiration and digoxin. The association of digoxin-disopyramide reduces the frequency of attacks of tachycardia and treatment may be stopped after one year's follow-up.
Explore the source record for details and available documents.
It is known that the pyridinium ring of a model compound such as N-methyl pyridinium chloride is cleaved by U.V. radiation at 254 nm. At acid pH the products obtained are methylamine and glutaconaldehyde. Under the same conditions desmosine and isodesmosine are degraded into lysine and probably into the homologous substituted ketone of glutaconaldehyde. At pH 6.0-7.0, a transient open-chain aminoaldehyde intermediate is observed which can either reform the original compound or be cleaved as at low pH. When intact elastin is photolysed for 20 minutes in water, approximately 75% of the (iso) desmosines are destroyed, accompanied by an increase of free lysine residues. No change in the concentration of the other amino acids, including tyrosine, are noted. It is therefore likely that the crosslinks engaged in peptide links are also cleaved photochemically.
Journal articles and several other types of publications concerned with human time estimation are divided into the following three chronological sections: 1960-1964, 1965-1969, and post 1969. Each section includes experimental, theoretical, and methodological papers.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.