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Biomedical subjects

M L de Portela

Publications and source records attributed to M L de Portela.

16 recordsLinked to original sources
PubMed2003

Bone mass changes in vivo during the entire reproductive cycle in rats feeding different dietary calcium and calcium/phosphorus ratio content.

The purpose of this study was to quantify in vivo the impact of different dietary Ca contents on the maternal total skeleton and skeletal sub-areas in adult rats during pregnancy and lactation, using DXA. Twenty-four female Wistar rats (approximately 5 months old) were mated and divided into three groups (n = 8) and fed one of the following diets, varying only in Ca content (LCD: 0.14%, NCD: 0.6% or HCD: 1.2%). Pups were adjusted to 8-9 per dam. Maternal ionic calcium and in vivo bone mineral density (BMD) were measured at the beginning, after delivery and after weaning. Regardless of the diet, ionized calcium decreased from onset to weaning ( P < 0.05). At weaning, bone mass decreased 7.3% in NCD, 15% in LCD and 10.5% in HCD from initial values. Total skeleton, whole and proximal tibia and spine BMDs only decreased at delivery in the LCD group ( P < 0.05) but, irrespective of the diet, at weaning, they were lower compared to delivery and initial values ( P < 0.05). LCD group presented the lowest BMD in the proximal tibia and spine regions ( P < 0.05). At birth, pups did not present differences, however, at weaning, LCD pups reached the lowest body weight ( P < 0.05), NCD presented the highest body Ca content ( P < 0.05) and there were no differences between LCD and HCD. This in vivo study showed that regardless of the dietary calcium content, the maternal skeleton is slightly affected by pregnancy but severely affected by lactation. However, the degree of such response appears to depend not only on dietary Ca content but also on dietary Ca/P molar ratio.

Absorptiometry, Photon↗
PubMed2000

Basal urinary zinc/creatinine ratio as an indicator of dietary zinc intake in healthy adult women.

OBJECTIVE: To study, in healthy women, the correlation between the basal urinary zinc/creatinine ratio and dietary zinc intake. SUBJECTS: A group of 36 healthy female University students was evaluated. Mean age and body weight were, respectively, 25.6+/-3.3 years and 54.4+/-7.0 kg. METHODS: Basal urine was collected; Zn was determined by AAS and Creatinine (Creat) by the Jaffe method. A nutritional survey of seven days was recorded. Mean daily dietary intake of energy (DE) and zinc (DZn) were calculated according to the INCAP and English or German Food Composition Tables, respectively. RESULTS: Mean dietary daily intake were as follows (x +/- SD): Energy (kcal): 1606+/-570; zinc (mg): 9.1+/-3.8; basal urine Zn/Creat ratio: 0.41+/-0.24. Individual values of the Zn/Creat ratio correlated with dietary Zn (r=0.481, p=0.0339); data grouped according to ranges of dietary Zn fit the following equation: Zn/Creat=0.160+/-0.034 DZn (mg/day); (r=0.870, p=0.00497). CONCLUSIONS: These results showed that the basal urinary Zn/Creat ratio could be a useful indicator of dietary Zn intake in healthy adult women.

Adult↗
PubMed1999

[Nutritional status of surgical patients without apparent nutritional compromise].

Nutritional status of 80 preoperative patients from programmed surgeries of hernias and lithiasis was studied by anthropometric and biochemical parameters. Nutritional deficiencies related to pathology were not expected in these patients. Results were as follows: 77% of the population showed overweight, being 15% obese. Prevalent protein intake, evaluated by the urea nitrogen/creatinine ratio, was adequate in 87.5% of the patients; however, patients presented 72% of albumin, 52% of prealbumin and 50% of RBP below reference values. Transferrin, ceruloplasmin, alpha 2-macroglobulin and haptoglobin were not decreased. Assessment of vitamin A, carotenes and vitamin C showed plasmatic levels below reference values in 16% of the patients for vitamin A, 5% for carotenes and 27% for vitamin C. Respect to calcium status, data of calcium/creatinine ratio show deficiency in 45% of the population. Respect to iron, the nutritional status was in general adequate, patients at risk being 5% by Htc, 11% by Hb, 5% by TS% and 12.5% by FEP, women showed over twice abnormal values than men. Although some isolated relations were observed, in this population sex, age and pathology were variable that did not affect in a relevant way the nutritional status. In spite of the individual analysis of each nutrient did not show important deficiencies, the analysis by patient showed that only a few of them (7%) presented an optimal biochemical profile with all the studied parameters within the reference values.

Adolescent↗
PubMed1999

[Investigation needs on carotenoids in the republic of Argentina].

There are no national dietary surveys regarding nutrient intake of Argentine population. On the other hand, nutrient content of foods in Argentina, as in other Latin American countries, is unknown because there are no data on food composition. Therefore, nutrient intakes must be calculated using foreign composition tables. In relation to vitamin A nutritional status, high prevalence of low vitamin A intake and low plasma retinol levels have been found in the eighties in several groups of university students. In this report, results of a 7-day dietary survey of students attending the course of Nutrition in the Universities of Buenos Aires, Luján and Tucumán are presented. Information was processed in a PC Computer (VAN Program, Lujan University, Argentina) to obtain the mean daily intake of carotenes with and without provitamin A activity, according to the German Food Composition Tables. The results showed that provitamin A carotenes provided between 40 and 82% of the vitamin A recommended allowances and that about 20% of the population had total carotene intake lower than 4 mg/day. These results are in agreement with other dietary surveys carried out in students in previous years and are a consequence of some characteristic feeding habits of the Argentine population. In order to obtain more reasonable results regarding actual intakes in our population, study of the composition of national foods would be imperative.

Antioxidants↗
PubMed1998

Influence of dietary calcium concentration on body size and bone composition in rats during recovery from malnutrition.

OBJECTIVE: The purpose of our study was to assess the influence of different levels of calcium (Ca) in a diet containing 30% protein on the rehabilitated of the body size from protein-energy malnutrition (PEM) and to establish the optimal Ca/protein ratio for attaining a normal body composition. METHODS: Weanling female Wistar rats were fed with protein-free diet up to a weight deficit of 20 +/- 1%. Then they were arranged in groups (TO) and fed diets with 30% protein and 0.0, 0.2, 0.4, 0.6, 0.9 or 1.2% Ca for 28 days (T28). Food and deionized water were given ad libitum. Body weight and length were recorded every 3 days. At T28, the animals were sacrificed to determine femur composition. RESULTS: At T13, weight-for-age (W/A) was within the normal range for rats consuming > or = 0.6% Ca. At T28 all groups showed adequate W/A. Although length-for-age was adequate during rehabilitated period, rate of weight gain improved when Ca was > or = 0.6%. Femur length did not show significant difference between groups. Total femur Ca content and mg Ca/g of dry-weight tissue increased with increments in dietary Ca concentration and tended to plateau with 0.4% Ca. Ca/P ratio reached the highest value with 0.9% Ca. CONCLUSIONS: Our findings indicate that at a dietary protein level of 30% the Ca/protein ratio is a limiting factor in attaining of normal body size; this is achievable when Ca concentration is 1.2% and the Ca/protein ratio is 0.04.

Aging↗
PubMed1993

[Free erythrocyte protoporphyrin as a function of age in growing rats].

The assessment of the iron (Fe) status is very important because its deficiency is one of the most common in both developing and industrialized countries, being particularly prevalent among infants and young children. Diagnosis is difficult in the presence of other conditions which interfere with the interpretation of laboratory tests, such as hemoglobin (Hb), hematocrit (Hct), serum iron, transferrin saturation percentage and serum ferritin. Free erythrocyte protoporphyrin (FEP) is a precursor of Heme and normally occurs in very low concentration in red blood cells (RBC); elevated values indicate early impaired iron nutritional status, providing information about gradual changes in the iron supply to the marrow. This laboratory test is a practical and convenient method because it needs a small blood sample easily preserved. Although the Second National Health and Nutritional Examination Survey (NHANES II) of USA has provided a good opportunity to define more precisely the cut-off points, it is doubtful whether the age-related differences in children represent normal development or the effects of iron deficiency. In order to provide information about these aspects the present experimental model was performed: weanling Wistar rats were fed until 95 days of age (t 95) with an isocaloric diet containing 20 or 30 g/100 g. of protein (casein) (N 20 and N 30, respectively), allowing the highest growth and erythropoiesis rates and covering the requirements of all the nutrients (Table 1). Body weight and food intake were recorded three times/week.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗
PubMed1989

[Interrelationship between vitamin D intake and absorption and retention of calcium during nutritional recovery].

We have previously reported that, in the first stages of nutritional recovery, the needs of undernourished infants, in terms of protein-calories percentage (P%) are higher than normal, producing an accelerated catch-up. Consequently, calcium (Ca) and phosphorus (P) balances increase proportionally to weight gain rate (WGR) in order to attain a normal body composition. As for the control of Ca metabolism by vitamin D, the question is whether vitamin D intake must also be increased during this accelerated catch-up growth period. In this report we have analysed retrospectively previous results in order to clarify the interrelationship between Ca absorption, Ca retention and vitamin D intake. A total of 29 undernourished infants, from 2 to 18 months of age, were fed Ad libitum with one of two proprietary milk formulas containing, per 100 g.: Ca, 0.50 and 1.17 g.; P, 0.37 and 0.50 g.; vitamin D, 350 and 400 UI (8.7 and 10 micrograms); proteins, 11.34 and 17.00 kcal/100 kcal of total diet, respectively. Recommended Dietary Allowances (RDA) of Ca and vitamin D, according to FAO/OMS and NRC, were calculated with reference to normal infants body weight and to 1000 kcal of recommended dietary energy intake. Ca intake was higher than the RDA and ranged between 60 and 413 mg/kg/day; intake of vitamin D increased proportionally to food intake; calcium absorption ranged between 40.0 and 92.0% (mean = 69.8 +/- 14.6) and CaB correlated with Ca intake (r = 0.97), being higher than normal.(ABSTRACT TRUNCATED AT 250 WORDS)

Calcium↗
PubMed1988

[Nutritional status with regard to calcium in Argentina].

Knowledge about calcium nutritional status in Argentina is scarce, due to the lack of systematic studies carried out in the country. For this reason, in the present report we have gathered information from data of food availability, nutritional surveys and the biochemical indicator Ca/Creatinine ratio in basal urine. All these data, jointly analyzed, allow certain extrapolations, based on which it is feasible to deduce conclusions as to the nutritional status in regard to such nutrient. Food availability data reveal an inadequate supply of calcium. On the other hand, the surveys, carried out for different purposes but with similar methodology, reveal a high percentage of deficient individuals, with reference to the Recommended Dietary Allowances (RDA) of the NRC (800 mg/day for adults). The use of the Ca/Creatinine ratio, in basal urine, confirms the high prevalence of Ca nutritional deficiency. Therefore, in our population which has a high protein consumption, Ca requirements are better reflected by NRC's RDA than FAO's (400 mg/day). These results clearly show that Ca deficiency is a generalized nutritional problem in the country. The causes seem to be not dependent on socioeconomic level, but would be closely related to dietary imbalance derived from the alimentary habits common to the Argentine population.

Adult↗
PubMed1984

[Calcium-creatinine in basal urine in relation to calcium intake and nutritional status in children under 3].

The calcium/creatinine ratio (Ca/Creat.) as an indicator of calcium nutritional status was evaluated in "basal urine" from 24 children comprised within the ages of three to 36 months during a 60-day period. The children were divided in normal or undernourished, according to Waterlow's classification. Children under 12 months of age were fed ad libitum with one of two commercial milk formulas, assigned according exclusively to the pediatric criterium. Children older than 12 months received milk besides the habitual hospital diet. In all cases the food intake was controlled and the calcium intake calculated. At the end of the study, basal urine was collected and calcium and creatinine determined. The results revealed that: a) In the normal children the Ca/Creat. ratio gradually decreased with age tending to a low value of 0.2 at the age of 36 months. The relationship between the Ca/Creat. ratio and the calcium intake showed a change in the slope when the requirements were met according to RNC (60 mg/kg/day); b) In undernourished children, the Ca/Creat. ratio was nearly constant whatever their age or calcium intake. The trend to approach the value of 0.2 for calcium intake (about 250 mg/kg/day), however, and the absence of the inflexion point, would suggest that the requirements of these children are far higher than the NRC recommendation, and that the change of the slope would be found for intakes over those obtained in our study. According to these findings, we conclude that the Ca/Creat. ratio in basal urine does not reflect calcium intake, but would depend on the bone calcium turnover. Consequently, it would be a simple and useful indicator of calcium nutritional status.

Calcium↗
PubMed1983

[Use of the urinary calcium/creatinine ratio as an indicator of the nutritional status of calcium].

The relationship between calcium and creatinine in basal urine for evaluating its usefulness as an indicator of calcium nutritional status was evaluated. Samples of basal urine were collected form a group of 5 to 12-year-old school children who followed a three-month program of dietary complementation. The calcium to creatinine ratio showed no correlation with daily total calcium intake. However, a correlation was found when intake was expressed in mg per kg of body weight (r = 0.67) and increased significantly when data were grouped according to growth rate (r = 0.85). On this basis, the Ca/Creat. ratio was analyzed as a function of weight gain (g/kg) for calcium intake: higher and lower than 10 mg/kg/day (4 = 0.82 and 0.89, respectively), the intercept of each line with the Y axis (null weight gain) being 0.096 and 0.068, respectively. These findings indicate the possibility of using the Ca/Creat. ratio in field studies as an indicator of nutritional status of the population in regard to calcium.

Body Weight↗
PubMed1983

[Relation between erythrocyte free protoporphyrins and usual iron intake in a group of University of Buenos Aires students].

In order to analyze the interrelationships between free erythrocyte protoporphyrins and the usual iron intake in adult students, biochemical, and hematological values, and dietary daily intake, obtained using the recall method during seven days, were studied. Hematocrit (Hto.), hemoglobin (Hb) and free erythrocyte protoporphyrins (FEP) were determined in a group of 145 female university students, healthy according to the standard parameters of the Buenos Aires University Health Department. Mean iron intake was 23.0 +/- 1.5 mg per day, about 44% being provided by animal sources; 74.5% of the population was within the recommended daily intake according to FAO/WHO; only 0.7% of the population did not cover protein requirements while 35% did not cover energy needs. Hto. and Hb were below normal levels in 7.8% of the population when compared with standards according to ICNND. To obtain information about normal values to FEP, expressed as microgram/100 ml red cells (FEP% r.c.) and FEP/Hb ratio, the group of students with adequate intake of energy and proteins who had normal values for Hb and Hto. was selected. This group, including 94 women, had a mean FEP% r.c. of 15.71 +/- 7.26 and a mean FEP/Hb ratio of 0.44 +/- 0.21. There was observed an inverse correlation between FEP% r.c. and FEP/Hb with total iron intake (r = 0.80 and r = 0.78, respectively) and between FEP% r.c. and Hb concentration (r = 0.81). These results confirm the usefulness of the free erythrocyte protoporphyrins determination as a good index of iron stores and usual intake of this population.

Adult↗