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Biomedical subjects

J Larralde

Publications and source records attributed to J Larralde.

At least 37 records · Page 2Linked to original sources
PubMed1992

Changes in serum and urinary amino acids after the administration of a mixed beta-adrenergic agonist.

The administration of the repartitioning agent metaproterenol, with affinity for beta 1- and beta 2-receptors, induced marked increases in gastrocnemius muscle and heart weights. The renal loss of essential amino acids was reduced in animals treated with beta-adrenergic agonists and a significant reduction in total serum amino acids was found as well. The assessment of urinary 3-methylhistidine suggests, that those changes were accompanied by a lower myofibrillar protein breakdown, while hydroxyproline output was increased as an indirect index of collagen turnover.

Amino Acids↗
PubMed1992

Potential induction of osteogenesis by systemic administration of bovine bone proteins.

This study shows, apparently for the first time, that the administration of bone derived proteins (putative bone growth factors) obtained from bovine demineralized maxillaries has a direct effect on osteogenesis, affecting significantly some markers of bone formation such as lactate dehydrogenase activity and serum osteocalcin. Also, collagen deposition and bone protein turnover were markedly increased by the treatment, which may have important biological and clinical applications.

Animals↗
PubMed1992

The influence of oral and subcutaneous administration of a mixed beta-adrenergic agonist on tissue and cell growth.

The non-selective beta-adrenergic agonist, metaproterenol, administered orally (2 ppm and 20 ppm) and subcutaneously (0.1 mg/Kg/d) for 21 days to young male rats induced no changes in animal growth or food intake. However, the rats treated with metaproterenol showed increased muscle gastrocnemius weight, which was accompanied by a muscle hyperplasia (DNA content increase) and a reduction in cellular size (protein/DNA ratio decrease). The beta-agonist did not affect liver growth or liver cellularity when assessed through the nucleic acid content. The increase in muscle mass was attributed, at least in part, to a reduction in protein breakdown as muscular cathepsin A activity was significantly lower in beta-agonist treated rats.

Administration, Oral↗
PubMed1991

Evidence of a short-term effect of growth hormone on in vivo bone protein synthesis in normal rats.

The growth of skeletal tissue is influenced by growth hormone (GH), whose effects are believed to be mediated, at least in part, by somatomedins or insulin-like growth factors (IGFs). This report describes an action of GH by increasing bone protein synthesis. This effect was not accompanied by changes in circulating IGFs. It is concluded that this experiment shows apparently for the first time in intact animals a short-term effect on bone turnover of GH.

Animals↗
PubMed1991

Anabolic actions of a mixed beta-adrenergic agonist on nitrogen retention and protein turnover.

Subcutaneous administration of a mixed beta-agonist induced increases in muscle (+13%) and heart (+17%) weights, which were accompanied by a reduction in back (-13%) and perirenal (-27%) fat stores in young male rats, while no changes in liver were observed. The values of nitrogen retention (mg/day) were significantly higher in the beta-agonist treated animals (+16%) as well as those of muscle DNA content (+8%). On the other hand, no statistically significant changes in muscle protein synthetic activity (g protein synthetized/g RNA) were detected (control: 13.4 vs treated: 14.6), while muscle proteolytic activity was decreased (-9%) in those rats administered with the repartitioning agent. In this context, it is suggested that the anabolic effect of metaproterenol should be attributed to a reduction in muscle protein degradation rather than to changes in protein synthesis.

Adipose Tissue↗
PubMed1991

Effects of cefroxadine on L-leucine absorption in rat jejunum.

The effect of cefroxadine, an aminocephalosporin (beta lactam antibiotic) on rat intestinal L-leucine transport has been studied. Cefroxadine inhibited the L-leucine uptake by the intestinal mucosa in a dose-dependent fashion. In vivo studies showed that cefroxadine reduced L-leucine absorption. This effect was irreversible. Only the active transport component of the absorption was inhibited. Oxygen consumption of the mucosa was reduced by cefroxadine which inhibited the activity of the basolateral (Na(+)-K+) ATPase also.

Animals↗
PubMed1991

[Homeorrhetic modifications produced by a beta-agonist in the muscle and adipose tissues of the rat].

A repartitioning effect was observed in young rats after a chronic treatment with a nonselective beta-agonist administered subcutaneously. An increase in carcass protein (P less than 0.05) accompanied by a reduction in fat stores (P less than 0.01) and an increase in back fat oxygen consumption (P less than 0.05) were found in treated animals. The muscle mass accretion should be attributed to a reduction in muscle protein degradation, based on lower activity of the proteolytic enzyme cathepsin A in treated rats, rather than to changes in protein synthesis, assessed by an amino-acid incorporation technique. The anabolic actions of this compound apparently involve changes in muscle prostaglandin E2 and reduction-oxidation state.

Adipose Tissue↗
PubMed1990

Effect of cefatrizine and cephaloglycine on L-leucine absorption in rat jejunum.

1. The oral cephalosporins: cefatrizine and cephaloglycine inhibit the L-leucine absorption in vivo on rat jejunum. 2. This inhibition is dose and time dependent and the effect is irreversible. 3. These antibiotics have a systemic effect on L-leucine absorption. 4. The inhibition of these antibiotics affect only leucine transport, without affecting the diffusion. 5. Cefatrizine and cephaloglycine inhibit the basolateral (Na(+)-K+) ATPase activity in rat jejunum.

Animals↗
PubMed1990

Repartitioning effect of a mixed beta-agonist on body composition.

Subcutaneous administration of a mixed beta-agonist to young rats induced no changes in animal growth and food conversion efficiency. However, a repartitioning effect was found with increases in lean tissue and decreases in body fat. The enhancement of muscle protein deposition was attributed to a fall in protein breakdown as muscular cathepsin A activity was lower in treated rats. A reduction of muscle reduction-oxidation state is associated to those changes in protein metabolism.

Adrenergic beta-Agonists↗
PubMed1989

Intestinal absorption of D-galactose in the presence of extracts from Phaseolus vulgaris hulls.

The relatively low nutritional value of protein from legume seeds has been attributed to the occurrence of some antinutritional factors and the poor content in sulphur aminoacids, which leads to undesirable physiological and biochemical alterations. However, the intimate nature of these processes remains unclear. In order to evaluate the influence of naturally occurring substances of legume constituents on nutrient utilization, the intestinal absorption of D-galactose in the presence of aqueous or alcoholic extracts, obtained from Phaseolus vulgaris hulls, has been measured by use of the in vivo successive absorption technique. Aqueous extracts inhibited significantly (p less than 0.01) the uptake of D-galactose at different times of exposure, while no changes in sugar transport were observed with the alcoholic solutions. Polyamide treatment (a polyphenolic complexing agent) of the aqueous extracts decreased its ability to inhibit sugar uptake. Kinetic studies showed that the aqueous fractions modify Vmax values for D-galactose absorption and also KT data. This inhibition appeared to be reversible after short periods of exposure, affecting mainly the active component of transport. Therefore, it can be suggested that some substances, contained in aqueous extracts of Phaseolus vulgaris reduce sugar absorption. Furthermore, our studies seem to indicate that polyphenols are, at least partly, involved in this phenomenon.

Animals↗
PubMed1989

A reappraisal of the nutritional utilization of legumes.

A survey of the physiological, biochemical and immunological changes found in growing mice, rats and chickens fed on raw legumes as the main source of protein from our experimental research is reported. Evidence is summarized about the fact that the inclusion of these vegetable proteins on animal diets brings about a number of undesirable effects such as stunting of growth, reduced protein deposition, altered digestibility and absorption of nutrients and impairment of the immune response, which have been attributed to the occurrence of various antinutritional factors and to a poor sulphur amino acid content. The possible role of tannins and phytates on some of those alterations is reviewed.

Animals↗
PubMed1988

Muscle and liver protein synthesis and degradation in growing rats fed a raw field bean (Vicia faba L.) diet.

Body weight gain, food intake, gastrocnemius muscle and liver weight, protein and RNA content, as well as the fractional rates of muscle and liver protein synthesis (ks, according to the method of constant infusion of L-[14C]tyrosine), growth (kg) and degradation (kd), along with RNA activity (g of protein synthesized per day/g RNA) of both organs, were determined in growing male rats fed ad libitum over a period of 10 days on 18.7% protein diets containing either casein (5% of methionine added) (control) or the raw legume field bean (Vicia faba L.) as the sole sources of protein. It has been found that as compared to control rats, those fed the raw legume diet exhibited a significant reduction in the rate of growth, muscle RNA, ks, kg, kd and RNA activity, and a significant increase in liver ks, kd and RNA activity. All differences were statistically significant at least at the 5% level. The possible nature of these findings is discussed.

Animals↗
PubMed1988

Effect of amoxicillin, cephalexin, and tetracycline-HCl on intestinal L-leucine transport in the rat in vivo.

By utilising an in vivo technique the effects of amoxicillin, cephalexin, and tetracycline-HCl on intestinal L-leucine absorption were studied in the rat. The results showed that amoxicillin caused a time-dependent and reversible inhibition of L-leucine transport while the inhibition induced by the other two antibiotics tested was not reversible. Light microscopic studies revealed that the three antibiotics were without effect on intestinal mucosal morphology.

Amoxicillin↗
PubMed1987

Iodide transport in rat small intestine: dependence on calcium.

1. The involvement of calcium in the regulation of iodide secretion was investigated in stripped sheets of rat small intestine. 2. In the absence of exogenous modifiers a net iodide absorption was observed in the rat proximal intestine, whereas the mid-intestine secreted iodide. 3. Removal of Ca2+ from the bathing solutions abolished net I- secretion in the mid-intestine. The calcium channel blocker verapamil produced similar effects on net I- secretion. 4. Theophylline increased net I- secretion both in the absence and in the presence of verapamil, but the effects of theophylline were less in the presence of verapamil or in Ca2+-free media. 5. Trifluoperazine inhibited basal iodide secretion and attenuated theophylline-induced I- secretion. 6. All the modifiers which prevented net I- secretion reduced iodide fluxes across the mucosal border and increased serosal iodide exit. The opposite was observed with theophylline. 7. It is suggested that I- secretion might result from changes in both mucosal and serosal I- permeabilities, and that both processes appear to be regulated by calmodulin.

Animals↗
PubMed1987

Response of muscle, liver and whole-body protein turnover to two different sources of protein in growing rats.

A significant impairment in growth rate, food efficiency and weight of the gastrocnemius muscle was observed in rats fed a raw legume as the source of protein compared to casein-fed animals. No appreciable differences in chemical composition of the carcass were found. The source of dietary protein did not influence the ratio protein/DNA, DNA concentration or protein-synthesizing capacity (RNA/protein). The slower weight gain of animals fed the legume diet was attributed to a lower muscle protein synthesis, mediated by a depression of muscle RNA activity (grams protein synthesized/gram RNA) rather than changes in myofibrillar protein breakdown. In contrast liver protein synthesis appeared to be slightly increased in the legume-fed animals.

Animals↗