Biomedical subjects

L A Cruz

Publications and source records attributed to L A Cruz.

8 recordsLinked to original sources

PubMed1998

A multimodal assessment of sensory thresholds in aging.

Young and elderly subjects yielded forced-choice detection thresholds in each of seven sensory tasks: (1) taste of sodium chloride, (2) smell of butanol, (3) cooling, (4) low-frequency vibrotaction, (5) high-frequency vibrotaction, (6) low-frequency hearing, and (7) high-frequency hearing. Average scores across these tasks nearly perfectly separated the 22 elderly from the 15 young subjects. For individual modalities, however, separation between the groups varied from complete (high-frequency touch) to negligible (low-frequency hearing). Scores on the Boston Picture Naming Test and especially the Wechsler Logical Memory Test correlated strongly with average threshold score (Pearson r = .80) and moderately with scores on individual modalities. This sensory-cognitive link is not caused, as might be supposed, by diminishing age-related capacity to handle the detection task, because the very same task resulted in negligible age effect (low-frequency hearing) and large effect (high-frequency hearing) in the same subjects.

Adolescent↗

PubMed1996

Spatial acuity of touch: ubiquitous decline with aging revealed by repeated threshold testing.

Spatial acuity of touch, like that of vision, tends to decline eventually in nearly everybody's lifetime. This has been revealed by more thorough than customary testing of individual young and elderly subjects. Three kinds of acuity threshold were assessed repeatedly in the index finger. These measured ability to discriminate tactile (1) gaps (by a refined version of two-point threshold), (2) orientation of lines (across vs. along the finger), and (3) length of lines. These acuities relate to prominent discriminatory features of braille, and have been shown earlier to average about 1% larger per annum over the adult life span from about 20 to 80 years. Although there were reliable differences among the elderly subjects in the present experiment, all of them tested consistently worse than the least acute young adult controls. The customary single brief threshold tests heretofore applied are inadequate to capture this ubiquitous but differential individual deficit in advanced age; however, the average of six 15- to 20-min tests spread over 3 days proved more than adequate. The method of repeated threshold testing--applied earlier to olfactory and gustatory sensitivity, and now to tactile acuity--serves to dispel the notion that incidence of sensory loss with aging is highly idiosyncratic.

Adult↗

PubMed1995

Taste sensitivity and aging: high incidence of decline revealed by repeated threshold measures.

Contrary to what has often been said about the subject, decline in taste sensitivity with aging characterizes virtually everybody and is not the artificial result of averaging large losses of a minority with negligible losses of a majority. This assertion is supported by six repeated measures of sucrose thresholds in each of 15 older (over 64 years) and 15 younger (under 27 years) adult subjects. Threshold was determined by a procedure similar to past studies and with the same results: much scatter and considerable overlap between the thresholds of younger and older subjects. A quite contrasting picture emerges, however, when each subject's six threshold determinations are averaged. Averaging shrinks the individual differences among subjects, as well as the over-lap between younger and older subjects. Although virtually all elderly subjects now revealed taste weakness, reliable individual differences in degree of weakness abound among them, suggesting various individual rates of physiological aging. In contrast, young persons exhibit greater uniformity of sensitivity. These findings were brought out by inter-test correlations, which were much higher for the older subjects; i.e. an older subject who tended to score high (low) on one test tended to score high (low) on the other tests. The study confirms the tenuous nature of brief threshold tests as indices of personal sensitivity as found earlier also in olfactory thresholds and in concurrent measurement of two-point touch thresholds in the present study. This revealed correlated losses between repeated taste and touch thresholds from the same 15 older subjects, unrelated to their exact chronological age.

Adult↗

PubMed1993

[Aortic insufficiency due to quadricuspid aortic valve].

In a 45 year old patient with clinic diagnosis of aortic regurgitation the two-dimensional echocardiography demonstrated a quadricuspid aortic valve and severe aortic regurgitation by Doppler. The quadricuspid aortic valve is a rare pathology, usually not associated with other cardiovascular pathologies and in which there is evolution with aortic regurgitation due to malposition of the four cusps.

Aortic Valve↗

PubMed1991

[Assessment of third-degree congenital atrioventricular block by ergometric tests].

PURPOSE: To analyse the use of the exercise testing as the method of initial evaluation, following a prognostic indicative of patients with congenital complete heart block. METHODS: Five patients were analysed (3 men and 2 woman) with ages between 7 and 34 years (mean = 22.8). The patients were submitted to a treadmill exercise testing using the Bruce protocol 1 and symptom limited. RESULTS: In all patients the atrial frequency increased from a median of 74.40 bpm in the basal to 155.20 bpm in the maximum effort; the atrial chronotropism was a little below that calculated based on the age of the patients. The median of the ventricular frequency in the maximum effort was 94.80 bpm, very different from that foreseen and showing a deficit of ventricular chronotropism. The median consumption of oxygen was 35.68ml0(2)/Kg/min. In one patients (20%) there was not any change in the ventricular frequency with the effort, in 3 (60%) complex ventricular arrhythmia arise during the effort and in one (20%) a definitive ventricular pacemaker was implanted. CONCLUSIONS: The exercise testing is a simple method of initial evaluation, providing information as chronotropism, functional capacity and the presence of arrhythmias, that can be very useful in the evaluation of prognostic. The presence of complex ventricular arrhythmias during the exercise is indicative of a more regular follow-up.

Adams-Stokes Syndrome↗

PubMed1990

Influence of solute degradation on the accumulation of solutes migrating into solution from polymeric parenteral containers.

Solute stability in solution, in addition to solute-polymer interaction properties and the total solute available pool, impacts the interaction between a polymeric container and a parenteral product, specifically in terms of the migration of trace polymer components into the contained solution. A specific solute/polymer system has been studied with respect to properties impacting the magnitude and rate of solute migration from the polymer into solution. The solute, an alkyl ester, originates in a polyolefin composite packaging material. Solute degradation kinetics were studied as a function of solution temperature and pH. Solute-polymer interaction properties including the equilibrium binding constant and diffusion coefficient were obtained. An accumulation rate model is developed for the determination of the solution phase concentration of the liberated solute as a function of storage time and conditions. Coupling the model with the properties of the polymer-solute system studied provides a tool that accurately predicts solute accumulation behavior in a representative parenteral product configuration.

Drug Packaging↗

PubMed1990

[The endodontist and AIDS].

Results of 235 surveys applied to odontologists performing root canal treatments to ascertain their general knowledge about AIDS. Special emphasis is made on preventive measures they take in their daily practice during handling of the patient, instruments and materials. The most outstanding characteristics of the disease are mentioned and some recommendations set forth for an adequate and safe treatment of the patient at the dentist's office.

Acquired Immunodeficiency Syndrome↗

PubMedDate not supplied

Accumulation model for solutes leaching from polymeric containers.

An accumulation model for predicting the equilibrium solution concentration of leachables migrating from polymeric containers has been applied to the leaching of several solutes from a blend of a styrene-butadiene-styrene block co-polymer and polypropylene. The model considers three accumulation-limiting mechanisms: total available pool, solute solubility and solute partitioning. Equations relating a solute's solvent-water partition coefficients (Po/w and Ph/w) and its polymer partitioning properties have been developed. With these equations, one can predict leachable accumulation from the container weight, solution volume and the solute's partition coefficients. The maximal accumulation of the leachable in solution will be the lowest value predicted via the three accumulation-limiting mechanisms.

Caproates↗