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Biomedical subjects

B Caballero

Publications and source records attributed to B Caballero.

At least 55 records · Page 3Linked to original sources
PubMed1989

Psychobiological effects of carbohydrate- and protein-rich meals in patients with seasonal affective disorder and normal controls.

Patients with seasonal affective disorder (SAD) frequently report carbohydrate craving and note that carbohydrate ingestion energizes them. Bright artificial light has been shown to reverse the symptoms of SAD, including carbohydrate craving. In this study, 16 depressed SAD patients and 16 matched controls were fed two different isocaloric meals, one rich in protein and one rich in carbohydrates, in a crossover design. Although their biochemical response in terms of plasma large neutral amino acid concentrations was identical, SAD patients reported activation following carbohydrate ingestion, whereas normal controls reported sedation. Marked ordering effects on psychological parameters were noted, suggesting that order should be taken into account as a methodological consideration in meal studies.

Adult↗
PubMed1989

Effects of running the Boston marathon on plasma concentrations of large neutral amino acids.

Plasma large neutral amino acid concentrations were measured in thirty-seven subjects before and after completing the Boston Marathon. Concentrations of tyrosine, phenylalanine, and methionine increased, as did their "plasma ratios" (i.e., the ratio of each amino acid's concentration to the summed plasma concentrations of the other large neutral amino acids which compete with it for brain uptake). No changes were noted in the plasma concentrations of tryptophan, leucine, isoleucine, nor valine; however, the "plasma ratios" of acid patterns may influence neurotransmitter synthesis.

Amino Acids↗
PubMed1988

Plasma amino acids and insulin levels in obesity: response to carbohydrate intake and tryptophan supplements.

We assessed the plasma amino acids, glucose, and insulin responses of obese and lean control subjects to midafternoon carbohydrate snacks. After a standard 400 kcal lunch, eight lean and nine obese subjects received, at 2PM, a 30 g sucrose snack; blood samples were obtained at hourly intervals until 6 PM. Each subject participated in four similar studies in which the carbohydrate snack was consumed alone or with 250, 500, or 1,000 mg of L-tryptophan (Trp), offered as a capsule. The obese group exhibited elevated plasma levels of the branched-chain amino acids, phenylalanine and tyrosine, and the levels of these amino acids declined much less in response to carbohydrate intake than in lean controls. As a consequence, the plasma ratio of Trp:large neutral amino acids (Trp/LNAA ratio), which normally rises after carbohydrate consumption, showed virtually no change in the obese group. The plasma Trp/LNAA response of this group did not reach control values even when carbohydrate intake was increased to 50 or 75 g. Peak plasma Trp concentrations and Trp/LNAA ratios after 250, 500, and 1,000 mg Trp doses were also significantly lower in the obese. Since brain Trp uptake is strongly correlated with the plasma Trp/LNAA ratio, which in turn determines the rate of brain serotonin synthesis, the blunted Trp/LNAA response to carbohydrate intake in the obese could contribute to alterations in the serotonin-mediated regulation of food intake.

Adult↗
PubMed1988

[Interactions among the components of the diet].

A large number of dietary interactions are described in this article. Of these, only a relatively small number have been proved of relevance for human nutrition, under the conditions of real diets. These interactions most often occur at the intestinal lumen, but they may also take place during the utilization or storage of nutrients. Traditional diets of developing countries, which usually include unrefined cereals and other sources of fiber, may inhibit the bioavailability of mineral nutrients, contributing to specific deficiencies. Drug-nutrient interactions may also affect the nutritional status, particularly in population groups such as the elderly, who frequently receive prolonged medication and may have an inadequate food intake.

Biological Availability↗
PubMed1986

The composition of lunch determines afternoon plasma tryptophan ratios in humans.

It is well established that the ratio of the plasma tryptophan concentration to those of the other large neutral amino acids determines the transport of tryptophan into the brain. Brain tryptophan levels, in turn, control production of the neurotransmitter serotonin. Protein-rich meals, when consumed in the morning after an overnight fast, have been shown to decrease the plasma tryptophan ratio, while carbohydrate-rich meals have the opposite effect. We now show that these meals have similar effects when consumed for lunch, even if they are preceded by a small breakfast meal.

Adult↗
PubMed1985

Homeostatic mechanisms in the utilization of exogenous iron in children recovering from severe malnutrition.

We evaluated the role of initial iron stores on iron accumulation during recovery from severe edematous protein-energy malnutrition in children. Twenty-six preschool children were divided in two groups according to their initial iron reserves, as estimated from serum ferritin concentration, using a cutoff criterion of 30 ng/ml. The low ferritin (LF) group had a mean serum ferritin level of 12 +/- 8 ng/dl, and the high ferritin (HF) group, 86 +/- 32 ng/dl. Both groups had similar degrees of malnutrition and of anemia, as defined by hemoglobin concentration. All children received an adequate therapeutic diet and 60 mg iron daily as ferrous sulfate. The recovery of biochemical and anthropometric indicators of nutritional status, as well as of hemoglobin concentration, was similar in both groups. On the contrary, the LF group showed a marked increase in serum ferritin concentration from the onset of treatment, whereas the HF group had a net decline in this parameter by 30 days, and a stable level thereafter. The difference in serum ferritin concentration between groups was maintained until day 60, and both groups ended the study (90 days) with similar levels. Estimation of the utilization of exogenous iron from changes in total-body iron during the first 60 days of recovery showed the LF group to retain an average of 9.3% of iron intake, whereas the HF group retained only 1.4%.(ABSTRACT TRUNCATED AT 250 WORDS)

Anemia, Hypochromic↗
PubMed1984

Effects of aspartame and glucose administration on brain and plasma levels of large neutral amino acids and brain 5-hydroxyindoles.

Administration of the artificial sweetener aspartame (L-aspartylphenylalanylmethyl ester; 200 mg/kg) by gavage to rats caused large increments in brain and plasma levels of phenylalanine and its product tyrosine. Glucose administration (3 g/kg, by gavage, a dose sufficient to cause insulin-mediated reductions in plasma levels of the large neutral amino acids leucine, isoleucine, and valine) also elevated brain phenylalanine and tyrosine, and enhanced the increments caused by the aspartame, nearly doubling the rise in brain phenylalanine. Each animal's brain phenylalanine or tyrosine levels were highly correlated (r = 0.97 and 0.99, respectively) with its plasma phenylalanine or tyrosine ratios, affirming that aspartame's effects on the brain amino acids result from the changes it produces in plasma composition. As described previously, glucose consumption increased brain tryptophan levels, and consequently, brain levels of the 5-hydroxyindoles serotonin and 5-hydroxyindoleacetic acid. Aspartame alone had no effect on these compounds but completely blocked the changes in 5-hydroxyindoles caused by glucose. Each animal's brain level of tryptophan (r = 0.89) and 5-hydroxyindoles (r = 0.74) was also significantly correlated with its plasma tryptophan ratio, affirming that the effects of glucose or aspartame on these brain constituents also result from the changes they produce in plasma composition. The aspartame-glucose combination also reduced brain levels of leucine, isoleucine, and valine to a significantly greater extent than aspartame or glucose alone. These observations indicate that high aspartame doses can generate major neurochemical changes in rats, especially when consumed along with carbohydrate-containing foods. However, they should not in any way be interpreted as demonstrating that aspartame significantly affects the human brain.

Amino Acids↗
PubMed1984

The effect of dietary lactose on the early recovery from protein-energy malnutrition. I. Clinical and anthropometric indices.

To assess the advisability of using lactose-containing formulas in the rehabilitation of severely malnourished children, indices of clinical recovery, growth and restoration of body proteins and gastrointestinal function were measured longitudinally during the initial 45 days of hospitalization in 20 male, preschool children with kwashiorkor and marasmic-kwashiorkor. All patients received a diet based on cows' milk, but half were allocated to a formula pretreated with beta-galactosidase to hydrolyze the lactose, while the others received the untreated, intact milk. The groups were identical with respect to clinical criteria on admission. For the final 37 days of the protocol, the subjects received 4 g of protein and 150 kcal of energy per kg per day. More diarrhea was experienced by the intact lactose group during early hospitalization. Overall, recovery was satisfactory in both cohorts, and there were no differences in rates of growth, body protein repletion, restoration of energy reserves nor intestinal functions. In conclusion, the routine reduction of lactose content from a milk-based diet for severe protein-energy malnutrition offers no advantages.

Animals↗
PubMed1984

The effect of dietary lactose on the early recovery from protein-energy malnutrition. II. Indices of nutrient absorption.

Absorption of dietary energy, nitrogen, carbohydrates and calcium, and retention of nitrogen and calcium were studied in 20 children with protein-energy malnutrition of the edematous type, using metabolic balance techniques and breath H2 analysis, to assess the advisability of using lactose-containing formulas in the rehabilitation of severely malnourished children. Ten patients received for 45 days a diet formula based on cows' milk (intact milk) and 10 similar children received the same formula pretreated with beta-galactosidase to hydrolyze the lactose (hydrolyzed milk). Dietary intakes were gradually increased to reach, on the 8th day, 4 g of protein and 150 kcal/kg. There were no differences between groups with respect to absorption or retention of the index nutrients. Postprandial carbohydrate malabsorption was occasionally observed in two patients with servings of the intact milk formula, and in one with the hydrolyzed milk diet. When the nutritional quality of a diet is assessed, the amount of nutrients that are absorbed and utilized are more important than the small, incompletely absorbed fractions that do not have significant metabolic or clinical implications. Therefore, the use of milk as the protein source for recovery diets is not contraindicated in the routine treatment of PEM.

Animals↗
PubMed1983

Fecal reducing substances and breath hydrogen excretion as indicators of carbohydrate malabsorption.

Data from serial determinations of fecal volume, characteristics, pH, and reducing substances, and postprandial breath hydrogen (H2) concentrations in severely malnourished children receiving milk-based recovery diets were used to evaluate the quality of the correspondence among diagnostic indices for carbohydrate malabsorption, with specific emphasis on the comparison of breath H2 excretion and fecal reducing substances. Only postprandial breath H2 results for subjects with a proven capacity to mount an H2 response to the nonabsorbable disaccharide, lactulose, were included. There was a poor correlation between the diagnostic indication provided by the breath test and fecal reducing sugars. Biological considerations about the metabolism of unabsorbed carbohydrates in relation to colonic transit time and fecal flora may explain the poor degree of correlation. The two indices should not be considered interchangeable, but should be used selectively in accordance with the clinical situation.

Breath Tests↗
PubMedDate not supplied

Epidemic optic and peripheral neuropathy in Cuba: a unique geopolitical public health problem.

During 1992 and 1993 an epidemic of optic and peripheral neuropathy affected over 50,000 Cubans. This occurred in the unique setting of a communist country which had a widespread health care network and wherein sudden changes in the economy affected most of the population. Although nutritional factors appeared to play a key role in the pathogenesis of the epidemic neuropathy, viral, toxic, and genetic factors were investigated by Cuban and North American scientists. The authors, representing different disciplines and different groups that visited Cuba during the epidemic, review and reflect on the clinical and laboratory findings which became available through their own experience and through reviewing the literature. The recent Cuban epidemic is compared to similar outbreaks of optic and peripheral neuropathy which have occurred in the past.

Alcohol Drinking↗