Biomedical subjects

J S Marchini

Publications and source records attributed to J S Marchini.

At least 37 records · Page 2Linked to original sources

PubMed1995

Iron from complex salts and its bioavailability to rats.

Complex iron compounds are being used as iron suppliers. Bioavailability of their iron was tested through several parameters. A biological iron prophylactic study in rats was simultaneously carried out with three of these iron complexes products: ferric orthophosphate, iron sodium EDTA and iron glycine chelate. Their iron biodisponibility was compared to that of ferrous sulfate. Five low iron diets were prepared according to AOAC method. Four of them were enriched to a level of 20 mg Fe/kg, with ferrous sulfate and the 3 iron complexes salts under study. These diets were offered to 5 groups of 6 weanling rats each in an iron prophylactic test. Food intake was measured during 5 weeks, weight checked weekly, blood and liver collected for analyses. Weight gain, hemoglobin, hematocrit, transferrin saturation, iron hemoglobin, biodisponibility and relative iron biological values were calculated. The prophylactic iron rat assay proved to be a feasible and practical model to test and compare iron salts biodisponibility. NaFeEDTA and iron aminochelate produced similar results as ferrous sulfate and their iron has a high biological value for the rats. Orthophosphate iron had lower biological value when compared to the reference standard ferrous sulfate and the other complex products studied.

Animals↗

PubMed1994

Drinking water as an iron carrier to control anemia in preschool children in a day-care center.

OBJECTIVE: Several foods have been used as iron (Fe) carriers to fight widespread global Fe deficiency and anemia. This paper describes the longitudinal effect of Fe-fortified drinking water given to a group of Brazilian preschool children. DESIGN: The experimental design included 31 preschool children who attended a day-care institution. Hemoglobin and serum ferritin were the blood parameters used to check the Fe status. Fe++ sulfate (20 mg Fe/L) was added daily to their drinking water container and measurements were obtained before the addition, 4 and 8 months later. RESULTS: The number of Fe-deficient children decreased drastically after they started drinking the Fe-enriched water. Mean hemoglobin values increased from 10.6 to 13.7 g/dL and serum ferritin from 13.7 to 25.6 micrograms/L. There were no problems related to the salt addition or to the children drinking the Fe-enriched water. CONCLUSION: Fe-enriched drinking water was shown to be a practical alternative to supply Fe to children attending a day-care institution.

Anemia, Hypochromic↗

PubMed1994

Effect of local diets with added sucrose on glycemic profiles of healthy and diabetic Brazilian subjects.

OBJECTIVE: We set out to determine the daily glycemic profile of healthy and non-insulin-dependent diabetes mellitus (NIDDM) persons and to test the hypothesis that small amounts of sucrose added to NIDDM meals would not change their responses. METHODS: Thirteen NIDDM and six healthy volunteers participated in the study. They initially consumed a diet similar to their home diet and later a diabetic hospital dietary regimen, with and without 30 g/day sugar replacing equivalent food energy. The hospital diet included their usual foods: bread, milk, rice, beans, meat, vegetables and fruits at breakfast, lunch and dinner. To follow their glycemic profile we drew several blood samples during a 22-hour period. RESULTS: The day-long plasma glucose profile of the NIDDM and healthy subjects showed similar patterns, increasing after the meals and returning later to baseline levels. The extra amount of sucrose consumed did not change the daily glycemic profile or the calculated glycemic area under the 22-hour glycemic curves. These results call attention to the importance of the 22-hour glycemic profile compared to other shorter glycemic indexes. CONCLUSION: The 22-hour profile has obvious advantage for planning day-long diabetic diets, taking in consideration local daily foods and usual eating habits. Maintenance of a small and traditional amount of food, e.g., sucrose, without harmful effects to the subjects, is another advantage of this proposition. It improves patient compliance as well as social daily life.

Adult↗

PubMed1994

Source and amount of dietary nonspecific nitrogen in relation to whole-body leucine, phenylalanine, and tyrosine kinetics in young men.

We studied the effects of amount and source of nonspecific nitrogen (NSN) on the oxidation of leucine and hydroxylation of phenylalanine. In phase 1, seven adult males received for 6 d diets providing indispensable amino acid intakes to meet the 1985 FAO/WHO/UNU (FAO) requirements or our proposed requirement values (MIT). During one diet period with each diet, the NSN of the basal diets (total nitrogen intake: 107 mg N.kg-1.d-1) was increased to a total of 160 mg N.kg-1.d-1. On the morning of day 7, an 8-h constant intravenous tracer-infusion protocol (3-h fast; 5-h fed state) was conducted with L-[1-13C]leucine, L-[ring-2H5]phenylalanine, and L-[3,3,2H2]-tyrosine as tracers. In phase 2, six subjects were given three diets for 6 d, supplying 107 mg N.kg-1.d-1; NSN was a mixture of dispensable amino acids in which glutamine accounted for 0%, 12.5%, and 100% of total NSN. Leucine oxidation and phenylalanine hydroxylation rates and whole-body leucine and phenylalanine balances were unaffected by addition of supplemental NSN to the diets in phase 1 or by amino acid source of NSN in phase 2. Leucine and phenylalanine balances were lower (P < 0.05) for FAO compared with MIT diets.

Adult↗

PubMed1994

Phenylalanine and tyrosine kinetics for different patterns and indispensable amino acid intakes in adult humans.

In a previous paper (Am J Clin Nutr 1993;58:670-83) we described results for plasma amino acid changes, leucine kinetics, and body leucine and nitrogen balance in 20 young men receiving diets for 3 wk. The diets were based on the 1985 FAO/WHO/UNU amino acid requirement pattern (modified FAO diet; n = 7), the Massachusetts Institute of Technology (MIT) requirement pattern (MIT diet; n = 7), or the egg-protein pattern (Egg diet; n = 6). It was concluded, in comparison with the MIT and Egg diets, that the modified FAO diet was not capable of maintaining body amino acid homeostasis or balance. Here we report results from tracer studies with L-[O-2H5]phenylalanine and [2H2]tyrosine that were carried out within the same experiment. The modified FAO diet failed to maintain a mean body phenylalanine balance as determined from rates of phenylalanine hydroxylation (corrected for deuterium-isotopekinetic effects); balance was achieved with the MIT and Egg diets. These results further underscore the inadequacy of the internationally proposed amino acid requirement pattern for healthy adults. We recommend interim use of the MIT, tentative amino acid requirement values in all considerations of adult human amino acid requirements and nutrition.

Adult↗

PubMed1994

Plasma proline and leucine kinetics: response to 4 wk with proline-free diets in young adults.

The effects of removing proline from the diet on plasma leucine and proline kinetics were investigated. After a 1-wk control period, during which young adult men received a diet containing a complete L-amino acid mixture, seven subjects were given for 4 wk a diet devoid of proline (group 1); six received a diet devoid of proline, arginine, aspartate, glutamate, and serine (group 2); and seven continued with the complete diet (group 3). At the end of the control and 4-wk periods subjects were given a continuous, (3-h fast, 5-h fed) intravenous infusion of L-[1-13C]leucine and L-[5,5-2H]proline. Plasma proline was reduced significantly, especially during the fed state, in groups 1 and 2 after the 4-wk diet periods. Small but statistically significant (P < 0.05) reductions occurred in nonoxidative leucine disappearance and leucine appearance during the fasted state in group 2. Proline fluxes decreased by approximately 50% in fasted and fed states in groups 1 and 2. Mean de novo proline synthesis during the fasted state declined markedly (P < 0.05) after 4 wk in groups 1 and 2.

Adult↗

PubMed1994

Methionine and cysteine kinetics at different intakes of cystine in healthy adult men.

We investigated plasma methionine and cysteine kinetics in eight healthy adult men receiving for 6 d each of five L-amino acid diets supplying 13 mg methionine.kg-1.d-1 without cystine or 6.5 mg methionine.kg-1.d-1 plus 0, 5.2, 10.5, or 20.9 mg cystine.kg-1.d-1. On the morning of day 7, primed, constant intravenous infusions of L-[2H3-methyl, 1-13C]methionine and L-[3,3-2H]cysteine were given for 8 h (for the first 3 h subjects remained in a fasted state and for the next 5 h received small, equal meals at hourly intervals to achieve a fed state). Methionine and cysteine fluxes and rate of methionine oxidation were estimated from plasma methionine and cysteine labeling and 13C in expired air. Methionine oxidation declined (P < 0.05) with lowered methionine intake. Cysteine flux was similar across diets and dietary cystine did not affect tracer methionine oxidation. If there is a sparing effect of dietary cystine on the methionine requirement in adults, it probably takes place during the "first-pass" removal of these amino acids within the splanchnic region.

Adult↗

PubMed1994

[Calculation of recommendations regarding protein intake: their application to preschool, school students and adults taking Brazilian foods].

The recommendations for protein consumption depend on the essential amino acid and total nitrogen content of a diet, and food digestibility. International recommendations are based on egg or milk proteins. However, populations eat different food mixtures. Brazilians use rice and beans as their main protein food source. This study presents different Brazilian diets, with variable amount of rice and beans. The results show that for each diet there is a different amount of protein recommended. Pre-school children, for example, must receive from 1.15 to 1.77 g/protein/day, depending on the mixture of their dietary protein intake. Besides the diet protein's quality and quantity, the total food intake and presence of other essential nutrients, such as iron, calcium and vitamin C has also to be considered. The correct protein recommendation with respect to a diet or a mixture of food, should take into consideration: digestibility, total nitrogen, essential amino acids, presence of others nutrients and weight of food consumed.

Adult↗

PubMed1994

Phenylalanine and tyrosine kinetics in critically ill children with sepsis.

To better understand the impact of severe illness on the amino acid economy and nutritional needs of pediatric patients, we studied plasma phenylalanine and tyrosine kinetics in eleven critically ill patients (six full-term newborns and five young infants). Within 48 h of the diagnosis of sepsis they were given primed constant i.v. infusions of L-[1-13C]phenylalanine and L-[3,3,2H2]tyrosine for 4 h. Routine nutritional support continued during this period by parenteral administration of dextrose, lipid emulsion, and an amino acid mixture low in tyrosine. Phenylalanine and tyrosine fluxes and rate of phenylalanine hydroxylation did not differ significantly between the two age groups, and so the data were combined for evaluation. For the entire group, values (mumol.kg-1.h-1; mean +/- SD) for phenylalanine and tyrosine fluxes and rate of phenylalanine hydroxylation were 132 +/- 24, 66 +/- 16, and 29 +/- 12, respectively. Plasma phenylalanine to tyrosine concentration ratio was 1.67 +/- 0.6. From a comparison of the rate of phenylalanine hydroxylation with measured phenylalanine intakes, it was concluded that their routine, clinical nutritional support was inadequate to achieve body phenylalanine balance. In comparison with published data, the relative rate of phenylalanine hydroxylation appears to be high. We speculate that tyrosine is a conditionally indispensable amino acid under these conditions; it would be desirable to establish the intake levels and ratio of phenylalanine to tyrosine that effectively support aromatic amino acid balance in these critically ill patients.

Bacterial Infections↗

PubMed1993

Phenylalanine conversion to tyrosine: comparative determination with L-[ring-2H5]phenylalanine and L-[1-13C]phenylalanine as tracers in man.

The in vivo rate of conversion of phenylalanine to tyrosine (PheOH) can be estimated using combinations of stable isotope-labeled phenylalanine and tyrosine. We have compared in four healthy adult men the rates of phenylalanine conversion to tyrosine based on the following pairs of primed, continuous tracer infusions administered simultaneously: (1) L-[ring-2H5]phenylalanine and 2H2-tyrosine with a 2H4-tyrosine prime, and (2) L-[1-13C]phenylalanine and 2H2-tyrosine with a 1-13C-tyrosine prime. Phenylalanine oxidation was determined from measurement of 13CO2 excretion in expired air. Tracers were given for 8 hours, with subjects being in the postabsorptive state during the first 3 hours and in the fed state during the remaining 5 hours. Mean (+/- SD) rates (mumol.kg-1.h-1) of phenylalanine conversion to tyrosine for fasted and fed states, respectively, were 5.1 +/- 2.9 and 6.8 +/- 3.4 with 2H5-phenylalanine and significantly higher (P < .05) at 11.1 +/- 5.6 and 12.7 +/- 7.7 with 13C-phenylalanine as tracer. Phenylalanine oxidation was 9.9 +/- 2.0 and 13.5 +/- 2.6, respectively, for fasted and fed states, and these mean values did not differ (P > .1) from the rate of phenylalanine conversion to tyrosine determined using 13C-phenylalanine. These results indicate the need for caution in interpreting kinetic aspects of phenylalanine metabolism when based on isotopic data from multideuterated phenylalanine.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1993

Requirements for indispensable amino acids in adult humans: longer-term amino acid kinetic study with support for the adequacy of the Massachusetts Institute of Technology amino acid requirement pattern.

Twenty young men received an L-amino acid diet, supplying 140 mg N.kg-1 x d-1 and patterned as in the Egg diet for 1 wk, and then for 3 wk either a pattern based on international recommendations (modified FAO diet; n = 7), our new amino acid requirement pattern (MIT diet; n = 7), or the egg pattern (Egg diet; n = 6). At the end of the initial week, at 1 and 3 wk with the three experimental diets, and after 3 d after return to the Egg diet, an 8-h continuous intravenous infusion with [1-13C]leucine (3 h fast, 5 h fed while subjects received hourly meals supplying the equivalent of one-twelfth the daily intake) was conducted. After 3 wk with the different diets, mean daily leucine balances were lower (P < 0.01) with the FAO diet (-160 mumol.kg-1 x d-1) than with the MIT diet (-15 mumol.kg-1 x d-1). Together with changes in plasma amino acid profiles [eg, methionine increased (P < 0.05) during feeding with the FAO and Egg diets but not with the MIT diet; increased proline concentrations during the fed state (P < 0.05) with the FAO diet but not with the MIT or Egg diets] we interpret these findings to indicate that the FAO diet is not capable of maintaining amino acid homeostasis, as is the case with the MIT and Egg diets.

Adult↗

PubMed1993

Vitamin C load test in elderly subjects.

Ascorbic acid fasting serum levels and levels after a test dose were carried out in a group of elderly subjects: nine men with 70 +/- 6 years and six women 74 +/- 7 years old. They live in the same old folks home and ate similar food. Their ascorbic acid intake was found to be around 20 mg/day. Fasting serum levels found lower values in the women. A load test showed a small increase in the hourly samples, supporting low tissue reserves of the vitamin. Factors such as low intake, absorption, metabolism, body mass and/or excretion of the vitamin in elderly population could explain these results. A marginal vitamin C deficiency is believed to be present in the group and extra ascorbic acid food supply seems to be recommended for these subjects.

Aged↗

PubMed1992

Phenylalanine and tyrosine kinetics in relation to altered protein and phenylalanine and tyrosine intakes in healthy young men.

Plasma phenylalanine (Phe) and tyrosine (Tyr) turnover and the rate of conversion of phenylalanine to tyrosine (Phehyd) and of phenylalanine oxidation (Pheox) after reduced intakes of Phe and Tyr were determined in a metabolic study involving five healthy young adult men. In a pilot study, six postabsorptive young men received either 12- or 4-h infusions of [2H2]Phe and [1-13C]Tyr or [1-13C]Phe and [2H2]Tyro. From these results a primed 8-h constant infusion of [1-13C]Phe and [2H2]Tyr and [2H3]leucine was used in the metabolic study (first 3 h fasted, the 5 h fed) at the end of 1-wk periods during which subjects received an adequate nitrogen L-amino acid based-diet followed by a restricted intake of Phe and Tyr. This procedure was again repeated after 1 and 3 wk when subjects were given a diet low in both nitrogen and Phe and Tyr. Phe and Tyr fluxes were not significantly affected by diet during the fasted metabolic state but Tyr fluxes were lower when the restricted intakes were given. Compared with the rate during the fasting state, Pheox was significantly higher (P less than 0.01) when the adequate diet was consumed; Pheox and Phehyd for fed and fasted states were similar when Phe and Tyr were restricted.

Adult↗

PubMed1991

Plasma amino acid patterns in alcoholic pellagra patients.

Plasma amino acid concentrations in 33 male alcoholic patients with pellagra (age 20-68 years) were compared with those in 17 healthy male subjects (age 20-45 years). Pellagra diagnosis was made on the basis of the typical clinical skin picture, and low urinary excretion of N'methylnicotinamide and N'methyl-2-pyridone-5-carboxamide (reduced by 70 and 80%, respectively, compared with controls). There were significant differences in body mass index, creatinine/high index and serum albumin between the two groups, indicating that besides pellagra the alcoholic patients had some degree of malnutrition. Of 17 plasma amino acids measured, the following had significantly lower concentrations in the pellagrins: tryptophan (3.65 vs 5.93 mumol/dl, pellagrin vs control), isoleucine (6.31 vs 11.13), leucine (11.54 vs 24.19), lysine (16.25 vs 34.47), methionine (2.61 vs 4.22), phenylalanine (5.71 vs 9.23), threonine (13.29 vs 26.81), valine (17.60 vs 41.06), alanine (42.54 vs 70.87), arginine (5.87 vs 10.09), tyrosine (5.57 vs 9.30). Glutamic acid was significantly higher in the pellagrins (18.45 vs 9.49). There was no difference between the groups of aspartic acid, glycine, histidine, proline and serine concentrations. It is concluded that pellagra is an important factor influencing the amino acid profiles in these patients. This finding should be taken into account when using plasma amino acid levels to assess the clinical status of the pellagrin.

Alcoholism↗

PubMed1990

Zinc acutely and temporarily inhibits adrenal cortisol secretion in humans. A preliminary report.

Hypo- and hyperzincemia has been reported to cause alterations in the adrenal secretion. To determine the acute effect of zinc on cortisol levels, we studied 27 normal individuals of both sexes aged 20-27 y after a 12-h fast. The tests were initiated at 7:00 AM when an antecubital vein was punctured and a device for infusion was installed and maintained with physiological saline. Zinc was administered orally at 8:00 AM. Subjects were divided into an experimental group of 13 individuals who received doses of 25, 37.5, and 50 mg of zinc and a control group of 14 individual who received 20 mL of physiological saline. Serial blood samples were collected over a period of 240 min after basal samples (-30 and 0 min). We detected an acute inhibitory effect of zinc on cortisol secretion during 240 min of the study period in the experimental group.

Adrenal Cortex↗

PubMed1990

Mechanisms and nutritional significance of metabolic responses to altered intakes of protein and amino acids, with reference to nutritional adaptation in humans.

Altered intakes of protein and amino acids modulate the rates of the major systems (protein synthesis, protein degradation, and amino acid oxidation) responsible for the maintenance of organ and whole-body protein and amino acid homeostasis. The cellular mechanisms responsible for such changes at low intakes are discussed. For oxidation amino acid availability is a primary determinant and protein synthesis is affected particularly at the initiation phase. Much remains to be learned about amino acid-dependent changes in mRNA synthesis, processing, turnover, and translation. The relationships between protein and amino acid intake and components of whole-body protein and amino acid kinetics are considered with reference to nutritional adaptation and accommodation. The limit of adaptation to protein intake cannot be lowered substantially beyond that for healthy adults whose habitual protein intake is generous. Metabolic control theory should be considered in the interpretation of results of studies dealing with amino acid requirement estimations.

Adaptation, Physiological↗

PubMed1990

Assessment of protein nutritional status.

An evaluation of protein status can be approached by use of anthropometric, clinical, and biochemical data, either singly or in combination, and further aided with dietary data. Each of these approaches has advantages and limitations. Biochemical evaluation has the potential of being the most objective and quantitative. Indicators that have been or might be used include plasma hormone responses to reduced protein intake, plasma levels of specific proteins or specific amino acids, urinary excretion of specific amino acids and other nitrogen-containing compounds, anthropometric and physical measurements of body muscle mass, and functional tests of muscle strength. Several measurements can be combined to produce nutritional indices of broader potential value. The importance of concomitant infection and inflammation, with its many effects on protein metabolism, cannot be ignored in making these assessments. Unfortunately, no single test or group of tests can be recommended at this time as a routine and reliable indicator of protein status. Nonetheless, our increasing knowledge of the metabolism and functions of proteins, together with the recent use of noninvasive stable isotope techniques and of sophisticated physicochemical measurements, provides encouragement that more appropriate indicators are in the offing.

Amino Acids↗

PubMed1990

Liver and kidney nitrogen uptake in rats fed beans enriched with 15nitrogen through (15NH4)2SO4 used as soil fertilizer.

This study was conducted to determine the incorporation of 15nitrogen (15N) into liver and kidney of a group of rats (N = 17) fed a mixture of cooked rice and beans for 4 weeks. The beans (Phaseolus vulgaris), grown in soil cultivated with (15NH4)2SO4, had 1.5% 15N enrichment. Three or four rats were sacrificed weekly and a control group (N = 13) received an isonitrogen and isocaloric reference casein diet. The amount of nitrogen transferred from the beans to the liver at the end of the first, second, third and fourth weeks was 17, 11, 27 and 29% of the total nitrogen, respectively. For the kidney, the respective values were 10, 9, 25 and 27% of the total nitrogen. The total nitrogen content of the liver and kidney of rats receiving the reference casein control diet was similar to that of the rice/beans animals. Weight gain was similar for the two groups, indicating the well-balanced biological value of the experimental diet. The present study shows that it is possible to monitor 15N incorporation into beans and subsequently into rat liver and kidney, in contrast to classical methods for protein metabolism evaluation which measure only total body nitrogen intake and excretion or weight gain.

Animals↗