Search PubMed⌕ Search

Biomedical subjects

S Guandalini

Publications and source records attributed to S Guandalini.

83 records · Page 5Linked to original sources
PubMed1979

Effects of heat-stable enterotoxin of Yersinia enterocolitica on ion transport and cyclic guanosine 3',5'-monophosphate metabolism in rabbit ileum.

Strains of Yersinia enterocolitica produce a heat-stable enterotoxin which is positive in the suckling mouse bioassay. Partial purification by a procedure previously worked out for heat-stable Escherichia coli enterotoxin yielded a substance which increases particulate guanylate cyclase activity and short-circuit current and inhibits active Cl-absorption in rabbit ileal mucosa. These effects of Y. enterocolitica enterotoxin are similar to those of heat-stable E. coli enterotoxin, suggesting a common mechanism of action.

Animals↗
PubMed1979

Influx of glycyl-proline and free amino acids across intestinal brush border of phenobarbital-treated rats.

In a previous study the authors have shown that treatment with phenobarbital in the rat is followed by a generalized increase of amino acid concentration in the plasma. In order to better clarify this phenomenon, the effect of phenobarbital on intestinal protein absorption was now studied by measuring the influxes of Glycyl-L-Proline, L-Phenylalanine, L-Lysine and L-Glutamic acid across the brush border of jejunum and ileum in rats treated with phenobarbital for two or four days. No significant changes of these influxes were observed in the treated animals as compared to the controls, hence suggesting that the effect of phenobarbital on plasma levels of free amino acids is not mediated by an effect on intestinal absorption. The rate of Glycyl-Proline influx as compared to those of amino acid influxes suggests the occurrence of a carrier-mediated transport process for this dipeptide in the rat intestine as previously shown in the rabbit.

Amino Acids↗
PubMed1977

Dipeptide transport in the intestinal mucosa of developing rabbits.

Influxes of glycyl-L-proline (a dipeptide which is not hydrolysed in the membrane and is transported intact across the brush border) and of glycyl-L phenylalanine (a dipeptide which has affinity for the peptide transport system and is hydrolysed at the brush border membrane) have been studied in the small intestine of fetal, newborn and suckling rabbits. For glycyl-L-phenylalanine, transport as the intact dipeptide and 'membrane hydrolysis + amino acid transport' have been measured separately by using glycyl-L-proline and L-leucine as selective inhibitors of each pathway. For comparison, uptake of free glycine and of free phenylalanine has also been studied. The intestine of newborn rabbits is shown to have a translocation process for intact dipeptides which is saturable with a low Kt and stimulated by sodium ions, and which is not shared by free amino acids. This process resembles that described in adult animals, except that the maximal velocity is much higher in newborns. The developmental pattern of this uptake process for dipeptides differs markedly from that of free glycine, thus providing a new type of evidence for the distinction between amino acid and dipeptide transport processes. The developmental pattern of the free phenylalanine uptake process also differs from the development of the 'superficial hydrolysis + amino acid transport' component of glycl-L-phenylalanine uptake. These data suggest that the advantage of mucosal uptake of peptides, compared to the uptake of free amino acids, is much greater in the early stages of postnatal life than in the adult.

Aging↗
PubMedDate not supplied

Effects of berberine on basal and secretagogue-modified ion transport in the rabbit ileum in vitro.

The antisecretory effect of berberine sulfate (BS) was determined in the rabbit ileal mucosa in vitro mounted in Ussing chambers. When present in the luminal side, the drug had no effect on potential difference (PD) or on the short-circuit current (Isc) changes induced by theophylline or prostaglandin E2 (PGE2). When present in the serosal medium at a concentration of 2 mM, however, berberine reduced PD and Isc and abolished residual ion flux (bicarbonate secretion) but had no significant affect on basal net Na and Cl transepithelial transport. BS effect on basal PD was not affected by the absence of Ca2+ in the medium; neither was it inhibited by the alpha-adrenergic blocker yohimbine. Serosally added BS effectively antagonized the secretory effect on Isc of agents that increase each of the known intracellular mediators of ion secretion: cyclic 3',5'-adenosine monophosphate (cAMP), cyclic 3',5'-guanosine monophosphate (cGMP), and Ca2+; it also inhibited the ion transport modifications evoked by PGE2. The drug had no effect on the concentration of cyclic nucleotides either under basal condition or in the presence of some secretagogues. Finally, BS did not impair the PD rise due to luminal addition of glucose.

Animals↗
PubMedDate not supplied

[Oral rehydration in infants with acute diarrhea: using a new preparation of reduced osmolarity].

Oral rehydration solutions (ORS) are widely employed in the treatment of acute diarrhea in children. Although several studies in the recent literature prove the efficacy and safety of newly formulated, reduced-osmolarity solutions, and a specific working group of the European Society for Pediatric Gastroenterology and Nutrition (ESPGAN) has made similar recommendations, such evidence in our Country is lacking. To this aim, we enrolled 38 children (age from 3 to 24 months, average: 8.2) with acute diarrhea lasting from no more than 5 days (average: 2.5). At observation, dehydration was found to be: absent in 12 (31.6%), mild in 19 (50%), moderate in 5 (13.2%), severe in 2 (5.2%). The last 2 patients were admitted and treated i.v., thus excluded from the study. In the 36 remaining children, a pathogen was identified in 25 (69.4%): Rotavirus in 18, Salmonella in 4, EPEC in 2, Cryptosporidium in 1. Stool Clinitest was positive in 7/31 children, all with Rotavirus infection. All the patients received ad libitum for the first 4-6 hours exclusively a reduced-osmolarity ORS formulated according to the ESPGAN criteria. Afterwards, they were fully re-fed and were also given the same ORS until diarrhea stopped. Most of the children accepted the ORS; those who refused it were either not dehydrated and/or older than 15 months. Thirty-three out of 36 children were fully rehydrated after 12 hours, without any side effects. We conclude that such an ORS is safe and effective in the treatment of children with acute diarrhea in our settings.

Diarrhea, Infantile↗