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Biomedical subjects

N Domingo

Publications and source records attributed to N Domingo.

50 records · Page 3Linked to original sources
PubMed1977

A comparative in vivo study of intestinal absorption of biliary phosphatidylcholines and micellar phosphatidylcholines in the rat.

An in vivo study was performed using rats with the purpose of comparing the absorption of native biliary and purified phosphatidylcholines. The latter were purified from bile and solubilized in the form of mixed micelles of bile salts-phosphatidylcholines-cholesterol. The animals all bore bile duct diversions, and were divided into two groups: one had a normal pancreatic secretion while in the other group the pancreatic duct was ligated. Animals with normal pancreatic secretion showed comparable rates of absorption of micellar and biliary phosphatidylcholines. In the absence of normal pancreatic secretion, the rate of absorption of biliary phosphatidylcholines was unchanged, whereas that of micellar phosphatidylcholines markedly decreased. The results are consistent with the concept that some biliary phosphatidylcholines are absorbed independently of pancreatic secretion in an unhydrolyzed form.

Animals↗
PubMed1977

Zone electrophoresis study of the bile lipoprotein complex.

Sucrose gradient column electrophoresis was performed with human hepatic and gallbladder bile. It is shown that bile phosphatidylcholines exhibit a more rapid anodic mobility than do bile salts and serum albumin. This high mobility of bile phosphatidylcholines is not due to the negatively charged lipids which are present in bile, i.e. bile salts or free fatty acids. It is demonstrated that phosphatidylcholines are associated with anionic polypeptides. Electrophoresis of reassociations between these purified polypeptides and dilaurylphosphatidylcholine showed that these anionic polypeptides are primarily responsible for the high anodic mobility of the bile lipoprotein complex. This work describes a procedure for the purification of the bile lipoprotein complex which can be useful for the study of other kinds of lipid-polypeptide associations.

Amino Acids↗
PubMed1976

The effects of acute and chronic ethanol administration on canine bile secretion.

In 9 conscious dogs (4 of whom were alcohol-fed for 24 months with 50% intragastric ethanol), provided with gastric and duodenal fistulae (Thomas cannula), the effects were studied of an acute iv ethanol infusion (1.3 g/kg) on hepatic bile secretory plateau levels after emptying of the gallbladder was induced by a continuous perfusion of secretin (0.5 CU/kg/hr) plus CCK-PZ (8 Crick-Harper-Raper U/kg/hr) and sodium taurocholate (0.62 mumol/kg/min). Acute iv ethanol infusion in nonalcoholic dogs reduced hepatic bile flow rate (29%), bile salt concentration (55%) and output (67%). In alcohol-fed dogs, acute iv ethanol reduced only the rate of flow (25%). Hepatic bile salt concentration and output plateau values were significantly higher in the alcohol-fed than in the nonalcoholic dogs. There were no significant differences between the two groups of dogs in the rate of evacuation, bile salt output, or lipid composition of gall bladder bile following a single iv injection of CCK-PZ.

Animals↗
PubMed1975

Diurnal changes of bile lipid concentration in hepatic bile of cholecystectomized man.

Diurnal variations of bile lipid concentration were studied in ten patients with a tube in the main bile duct following a cholecystectomy. 5-6 bile samples per 24 h were collected from each patient during 3-40 days. The enterohepatic cycle was not significantly modified since total bile samples did not exceed 40 ml/day. Significant diurnal variations were observed in cholesterol concentration. Changes in lecithin concentration seemed to be similar in seven patients but did not reach the level of significance in any individual patient. Maximal values were observed between 4 and 8 a.m. and minimal values at 4 p.m. Bile salt concentration varied without any circadian periodicity. Mean bile lipid concentration was calculated for each patient. The patients with highest cholesterol concentrations have also the highest mean lecithin concentration. Mean bile salt concentration does not differ much from one patient to another.

Adult↗
PubMedDate not supplied

Intralipid 10%: physicochemical characterization.

OBJECTIVES: Parenteral fat emulsions contain two populations of particles: artificial chylomicrons rich in triacylglycerols (TAG), and liposomes (bilayer of phospholipids [PL] enveloping an aqueous phase). Centrifugation permits isolating the liposomes in the infranatant called mesophase. The aim of the present work was to better characterize this mesophase chemically and to view the particles it contains by electron microscopy. METHODS: Electron microscopy (Philips 410) was performed after cryofracture on native 10% Intralipid, mesophase (centrifugation for 1 h at 27 000 g), and a liposome-enriched fraction (ring of density 1.010-1.030 g/l obtained after centrifuging mesophase in a KBr density gradient at 100 000 g for 24 h). The TAG and protein content of the mesophase was analyzed and the proteins partially characterized by immunodetection (Western-blot). RESULTS: This electron microscope study of 10% Intralipid gives evidence for the coexistence of artificial chylomicrons (mean diameter, 260 nm) and liposomes (43 nm), the latter being smaller than expected and containing 8% w/w TAG after purification. The solubilization of TAG in PL bilayers (reported to be < or = 3.1% w/w) might have been increased in parenteral emulsions by the manufacturing process or/and the high TAG/PL ratio. Minute amounts of proteins have also been detected and partially characterized using a specific antibody raised against the human 7 kDa Anionic Polypeptide Factor (APF), known to strongly interact with PL in bile. CONCLUSIONS: This work has shown that the size (mean diameter, 43 nm) of the liposomes present in 10% Intralipid is smaller than that usually assumed. Traces of hydrophobic proteins in the emulsion may account for certain allergic reactions sometimes observed in infused patients.

Blotting, Western↗
PubMedDate not supplied

Effects of dexamethasone and linoleic acid on hepatic secretion of biliary lipids and anionic polypeptide factor: In vivo and in vitro studies.

Synthetic glucocorticoids, such as dexamethasone, and diets enriched with unsaturated fatty acids have been shown to stimulate hepatic bile salt synthesis. This fact led us to investigate the effects of dexamethasone and linoleic acid supplementation on bile secretion. Cholesterol (Ch) and phospholipid secretions are bile acid dependent. Ch and phospholipid in bile are also highly bound to a small apoprotein, the anionic polypeptide factor (APF). In bile, APF may play a physiological role in stabilizing cholesterol:phospholipid vesicles and might also be important in the regulatory process of bile lipid secretion. In order to study the factors influencing bile secretion, the biliary secretion rates of bile lipids and APF were experimentally modulated in perfused rat liver (PRL) and HepG2 cells. As expected, dexamethasone induced an increase in the biliary secretion rate of bile salts (BS) in the two models (PRL: 34 up to 67 nmol/l/min/g liver; HepG2 cells: 234% vs. 100% in controls). The bile secretion rates for phospholipids (PRL: from 5 down to 1.5 nmol/l/min/g liver; HepG2 cells: 93 vs. 100% in controls) and APF (PRL: from 0.34 down to 0.12 microg/l/min/g liver; cells: 86 vs. 100% in controls) rapidly decreased independently from those of BS. The data from experimental cell models supplemented with linoleic acid indicated a correlation between the BS and APF levels (APF: 71 and 63%; BS: 161 and 197% vs. 100% in controls). The phospholipid level was regulated independently from that of APF and BS and increased (106 and 111% vs. 100% in controls), while Ch remained nevertheless unchanged. Our data showed that dexamethasone induced changes in bile and that linoleic acid clearly impaired the regulation exerted by the dexamethasone on bile lipids.

Animals↗