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O de Freitas

Publications and source records attributed to O de Freitas.

5 recordsLinked to original sources
PubMed1999

Influence of formulation on the physicochemical properties of casein microparticles.

Casein microparticles (CAS/MP) have a potential clinical use for targeting drugs. However, the use of organic solvents in their preparation is undesirable. This study was designed to investigate the influence of preparation procedures in aqueous media on the formulation and physicochemical properties of CAS/MP. The first stage involved the influence of the coacervating agents (lactic acid, succinic anhydride, succinic acid and tartaric acid). The second stage studied was the influence of the ionic strength and the third, the influence of adding a thickener, hydroxypropyl cellulose or hydroxypropyl methycellulose (HPC or HPMC), and a plasticizing agent (gelatin). Some physicochemical properties of CAS/MP were evaluated. While the infrared and the thermal analysis showed that all coacervating agents were appropriate for coacervation, the scanning electron microscopy studies showed that the external morphology of the particles was more homogeneous when lactic acid was used. Utilizing lactic acid as the coacervating agent, there was a trend effect of adding NaCl implying that the increasing of the ionic strength resulted in better stability. Finally, the addition of 0.1% HPC plus either 0.25 or 0.5% gelatin resulted in homogeneous formulations. In conclusion, the use of lactic acid plus 0.1% HPC and 0.25% gelatin results in biodegradable and homogeneous CAS/MP, presenting a potentially useful drug delivery system.

Animals↗
PubMed1999

New approaches to the treatment of phenylketonuria.

Phenylketonuria (PKU) is the most common of all aminoacidopathies and is caused by autosomal recessive deficiency of the hepatic phenylalanine hydroxylase system. The diagnosis of PKU should be multifactorial and based on a protein overload test that reveals increased plasma phenylalanine levels during the ingestion of a normal diet, a phenylalanine tolerance test, and in vitro and in vivo activity of the liver enzyme. An individualized diagnosis that characterizes the severity of the disease in each patient provides objective and effective criteria for the dietary treatment of each particular case.

Animals↗
PubMed1996

Effect of chronic ethanol consumption on the activities of residual small bowel brush-border enzymes after proximal jejunum resection in the rat.

Ethanol consumption has a toxic effect on the epithelium of the small bowel, but enterocyte maturity is very difficult to measure under these circumstances. However, when ethanol intake is combined with enterectomy, enterocyte immaturity is greater, permitting an easier separation of these two effects. In a group of rats (13 male Wistar rats weighing approximately 220 g) fed a liquid diet containing 35% ethanol for 4 weeks after resection of the proximal jejunum, the residual small intestine brush border maltase, sucrase, and lactase activities were similar to those of a pair-fed control group (13 animals). However, alkaline phosphatase activity was decreased in the mucosa and in the enterocyte brush border, probably because of the lower activity of this enzyme in the jejunum-ileum remnant of the alcoholic group.

Alcoholism↗
PubMed1995

Casein, hydrolyzed casein, and amino acids that simulate casein produce the same extent of mucosal adaptation to massive bowel resection in adult rats.

We determined the effect of the extent of protein polymerization on the intestinal hyperplastic adaptation of adult male Wistar rats after 80% resection of the jejunal-ileal segment. Rats received one of four chemically defined solid diets prepared by using casein, two casein hydrolysates of different peptide size distributions, or free amino acids simulating casein and identical in all other components for 12 d, starting 3 d after surgery. Semipaired feeding was used to ensure that the same quantity of food was ingested by each group and as a consequence, nitrogen and energy intakes were reduced to 63% of that obtained with ad libitum feeding of the casein diet to intact rats. No significant differences were demonstrable in food ingestion, weight gain, nitrogen balance, or morphometric data for the remaining jejunal and ileal segments (number of cells/villus, number of cells/crypt, and crypt cell mitosis rate). These data demonstrate that the extent of polymerization of the protein nitrogen source did not affect the hyperplastic adaptative process of the rat. Additional studies in humans are necessary to determine whether intact protein diets can be used first as a nitrogen source in nutritional support of patients with a nonspecific hyperplastic response to surgical resection before the use of expensive hydrolysates and the more expensive amino acid mixtures.

Adaptation, Physiological↗