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Biomedical subjects

E Vargas

Publications and source records attributed to E Vargas.

At least 73 records · Page 4Linked to original sources
PubMed1986

Preoperative clinical predictors of long term survival in mitral stenosis: analysis of 200 cases followed for up to 27 years after closed mitral valvotomy.

Two hundred patients aged 17-40 years undergoing closed mitral valvotomy during 1955-60 were studied by actuarial survival analysis. The period of follow up was 22-27 years. The following preoperative features were found to be independent predictors of long term survival: sinus rhythm (p less than 0.05); pulmonary arterial pressure below systemic pressure (p less than 0.01); absence of congestive cardiac failure (p less than 0.01) and pure mitral stenosis (p less than 0.01). A better long term survival was found for mitral valvotomy with a Tubb's dilator than finger splitting or Brock's method. The presence of calcification at the time of valvotomy adversely affected survival (p less than 0.01). Anticoagulation improved survival (p less than 0.01). It is concluded that closed mitral valvotomy gives good results if performed before the onset of established atrial fibrillation and congestive cardiac failure and that all patients should have anticoagulation. These results have important implications for selection of patients in countries with limited facilities for open heart surgery.

Adolescent↗
PubMed1986

[Chemical composition and biological value of tortillas and bread produced on the commercial level in Costa Rica].

A study was conducted to evaluate the nutritive value of tortilla, wheat bread, and tortilla meal. Six types of tortillas, five breads and two tortillas meal were thus studied. Chemical composition of each product was determined, and biological trials in laboratory rats were also carried out with each of them. Results demonstrated that the corn products had a better protein quality than the wheat products. Furthermore, little variability in nutrient content and protein quality (NPR) between the different corn and wheat products was found. The utilizable protein content of the wheat products was higher than that of the corn products, while the gross energy content was similar for both. An economical-nutritional analysis revealed that the corn-soybean tortilla meal is the most nutritive and economic product to provide basic nutrients (protein and energy) to the population.

Animals↗
PubMed1985

[A new alternative for estimating recommendations of protein intake in humans. Protein requirements of an adult population fed with a diet based on rice and beans].

This paper proposes a new approach to estimate the protein needs of a population; recommendations are also made on the protein intake of adults fed diets based on rice and beans. For this purpose, the nitrogen balance data previously reported for 40 adult human subjects who had participated in 160 nitrogen balance periods fed diets based on rice and beans, with and without animal protein and/or energy supplementation were used. The proposed method is based on the curvilinear response between nitrogen intake and its nitrogen balance. The second degree equation describing the relationship between nitrogen balance and intake is calculated. Using the mathematical concept of the first and second derivatives, the point of inflexion is obtained, and interpreted as that condition wherein the individual utilizes with maximum efficacy the ingested nitrogen; nitrogen ingestion, which corresponds to that point, is therefore taken as the dietary nitrogen recommendation for the individual. When the values obtained by means of the quadratic equation are compared to those obtained by the traditional linear equation, values were found to be statistically equal (p less than 0.05) for both calculation methods. The recommended protein intake of an adult population fed a diet based on rice and beans was 0.80 and 0.77 g/kg/day for the quadratic approach, and for the conventional method, respectively. When this diet was supplemented with 10% milk protein and with the same energy level, the calculated values were 0.64 and 0.71 g protein/kg/day for both methods, in this same order. The essential amino acid intake and absorption values were also calculated from the protein levels recommended by both methods to be in nitrogen balance, from a diet based on rice and beans. Findings revealed, in all cases, that the intakes of each and all essential amino acids met those levels indicated by FAO/WHO, with the exception of isoleucine and the sulphur-containing amino acids, which apparently limit the quality of the diet.

Adult↗
PubMed1985

[Biological evaluation of an infant food based on soybean, rice and banana].

An infant food, a mixture of soy, rice and banana was biologically evaluated in three studies carried out in Sprague-Dawley rats. In the first assay, the caloric supplementation and milk protein complementation effect on the nutritive value of the product was studied. Results indicated that an equal nutritive value as that of milk is obtained when 50% of the vegetable protein is replaced by animal protein. The fact that caloric supplementation does not exert any positive effect on the nutritive value of the infant food, under the conditions of the study, was also confirmed. In the second assay, the effect of amino acid (lysine and methionine) supplementation was evaluated. Results revealed a significant improvement of the product quality with lysine supplementation, a finding that implies thermal protein damage caused by industrial processing. In the third study, whole milk supplementation effect at the levels that the product could be offered in school lunch programs and Nutrition and Education Centers was investigated. Such values, as determined, correspond to 343 to 655 ml of fluid milk per 100 g of the cereal product. It was also found that milk complements and improves the nutritive value of the product at equal statistical (P less than 0.05) values as those of milk.

Animals↗
PubMed1984

Caudate unit activity and somal diameters in intact and nigral lesioned cats.

In a search for morphofunctional relationships in the head of the caudate nucleus (CN), we recorded extracellular unit activity in intact cats and in cats that had received bilateral injections of 6-OHDA into the substantia nigra (SN) 30 days previously. Only units firing spontaneously and continuously for 2 min were studied. In dorsal regions, potentials were small and iterative at almost constant intervals; the somal diameters were relatively small. In the ventrolateral region, potentials were bigger and appeared in bursts; somal diameters were significantly larger (p less than 0.05). For the centromedial region a histogram of numbers of neurons as a function of diameters revealed a Gaussian distribution extending from small to large neurons. Most dorsal neurons increased their firing rate to radial nerve, visual, SN, and/or nucleus centralis medialis (NCM) stimulation. Ventral neurons usually responded with excitation followed by long lasting inhibition, particularly to SN and NCM stimulation. A few neurons responded to all four inputs and some showed long-lasting potentiation in response to low frequency stimulation, suggesting a more general function. Greatest convergence (65%) was found for NCM and SN inputs. In lesioned cats, there was no SN driving, NCM's inhibitory actions almost disappeared, and the excitatory action of the other stimuli was reduced.

Animals↗
PubMed1984

Plasma arginine vasopressin in dehydrated elderly patients.

Plasma arginine vasopressin was assessed by radioimmunoassay in dehydrated elderly patients and healthy young and elderly control subjects. The elderly control subjects' AVP levels were higher than the young control subjects (Kruskal-Wallis rank sums z = 3.29; P less than 0.001). Despite similar plasma osmolalities, after correction for the osmotic contribution of urea, the patients' AVP levels were higher than the elderly controls (z = 4.16; P less than 0.001) and were in the range reported to evoke a maximal antidiuretic response. It is concluded that the dehydration which often accompanies acute illness in the elderly is not primarily a consequence of inadequate AVP release.

Adult↗
PubMed1984

The measurement of plasma noradrenaline before and after tilt in young and old healthy subjects.

Using a modified sensitive and specific radioenzymatic method we have determined the normal range for plasma noradrenaline in healthy, elderly individuals. The effects of tilt on the cardiovascular system and on plasma noradrenaline responses were found to be different compared with healthy young controls. The elderly had higher resting plasma noradrenaline concentrations with an exaggerated response to head-up tilt. In spite of this higher sympathetic drive, the cardiovascular responses in the elderly were attenuated.

Adult↗
PubMed1984

[Protein digestibility and energy in diets based on rice and beans in human adults].

Four studies were carried out for the purpose of measuring the digestibility of diets based on rice and beans (Phaseolus vulgaris), and in order to quantify the effect of their supplementation with animal protein (milk) and energy (oil), on the energy and protein digestibility of such diets in human adults. Diets were offered so that they supplied 46, 72, and 103 mg N/kg/day. When the basal diet--where rice provided 60% of the protein and beans 40%--was administered at a level of 102.5 mg of nitrogen/kg/day and 49.5 Kcal/kg/day of gross energy, an apparent and true nitrogen, energy and metabolizable energy digestibility of 59.1, 70.8, 93.8 and 92.5%, respectively, were observed. When substituting 10% of the vegetable protein by milk protein in the same diet, the same indicators revealed a digestibility of 65.3, 76.8, 93.5 and 92.1%, respectively. The information indicates that supplementation with animal protein improves nitrogen absorption at any of the energy levels studied. In contrast, caloric supplementation does not have any positive effect on nitrogen or energy absorption. It was also found that nitrogen apparent digestibility increases significantly when the N level in the diet is raised, and stabilizes when intake exceeds 100 mg nitrogen/kg/day. It is therefore proposed that for digestibility studies in diets where animal protein is utilized at a nitrogen level of around 120 mg/kg/day, true digestibility remains constant, no matter what nitrogen level is used in the diet.

Adult↗
PubMed1984

[Effect of animal protein supplementation and energy on the protein quality of diets based on rice and beans in adult males].

Four short nitrogen balance index studies were carried out in adult subjects to evaluate the biological quality of a mixture based on rice and beans, and also to measure the effect of animal protein and/or energy supplementation on the nutritive value of the mixture. In the first study, rice supplied 60% and beans, 40% of the protein's diet, which was administered at an energy level of 45.5 kcal/kg/day of metabolizable energy. A regression coefficient of 0.76 +/- 0.11 was found between ingested nitrogen and nitrogen balance, and a value for nitrogen maintenance of 96.2 +/- 13.7 mg/kg/day. When this same diet was administered in the second study at a 51.2 kcal/kg/day of metabolizable energy, the regression coefficient was 0.80 +/- 0.13, and that of nitrogen for maintenance, 90.1 +/- 8.7 mg/kg/day, without differences being significant (P less than 0.05) for any of the two measures. In the third study, 10% of the mixture's protein was substituted by milk protein, and given at a level of 45.2 kcal/kg/day of metabolizable energy. In this case, the regression coefficient found was 0.96 +/- 0.08, and that of nitrogen for maintenance, 78.6 +/- 10.2 mg/kg/day. These values do differ significantly (P less than 0.05) from those found in the two previous studies. When the diet of the third study was administered to the same subjects at a level of 48.9 kcal/kg/day of metabolizable energy, the regression coefficient of the equation was 0.86 +/- 0.17, and that for maintenance nitrogen, 82.4 +/- 10.2 mg/kg/day. These values are statistically equal to those found in the third study and do differ significantly from those of the first two studies. Information indicates that the supplementary effect of protein and milk occurs mainly at the digestive level. It is therefore concluded that when rice and beans are consumed jointly, in the adequate proportions, they constitute an excellent-quality food for adult humans.

Adult↗
PubMed1983

Indican excretion in the elderly.

It has been suggested that up to a half of elderly hospitalized patients excrete an abnormally high concentration of indican compared with young individuals. Thus, the commonly used colorimetric qualitative test for urinary indican excess may be invalid in the aged. However, of 21 young control subjects, 18 healthy elderly subjects, and 23 disabled, elderly, long-stay patients, no individual had levels of indican detectable by the standard colorimetric qualitative test. The use of a quantitative assay demonstrated that urinary indican concentration is similar in young and elderly individuals. A diurnal variation in urinary indican concentration was discovered which may affect the interpretation of the qualitative test.

Adult↗
PubMed1982

Physiological responses to postural change in young and old healthy individuals.

The cardiovascular responses to 70 degrees head-up tilt were compared in 9 healthy young, mean age 31 +/- (S.D.) 3.2 years, and 8 healthy elderly subjects, mean age 71 +/- 5.1 years. After 10 minutes tilt, qualitatively similar responses were found in the two groups. Quantitatively, however, heart rate, stroke volume, cardiac output, and peripheral resistance showed smaller differences between the supine and tilt positions in the older group. Blood pressure and plasma volume changes were similar in both groups. There is an age-associated effect in the cardiovascular response to change in posture in healthy people that resembles that found in congestive cardiac failure.

Adult↗