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Biomedical subjects

B Lombardi

Publications and source records attributed to B Lombardi.

At least 73 records · Page 4Linked to original sources
PubMed1979

Acute hemorrhagic pancreatic necrosis in mice: lack of a pathogenetic role for complement.

Feeding a choline-deficient diet containing 0.5% DL-ethionine induces an acute hemorrhagic pancreatitis in 100% of young female mice. Evidence for deposition of the third component of complement (C3) on acinar cell plasma membranes was sought, during the inductive stages, by a sandwich immunofluorescence technique. Such a localization could not be demonstrated even though the method is capable of detecting less than 8 x 10(-5) microgram of protein/mm2 of cell membrane. Artifactual binding of immunoglobulin reagents was encountered when goat antisera, with high levels of circulating immune complexes, formed the middle layer in the sandwich technique. This was attributed to the appearance of Fc receptors on the plasma membrane of degenerating acinar cells, and could be avoided by ultracentrifuging acinar cells, and could be avoided by ultracentrifuging the goat antisera prior to sue. In view of the fact that C3 cleavage represents an amplification loop in both the calssical and alternate pathways of complement activation, the lack of demonstrable C3 staining in tbe present experiments strongly suggests that complement plays no role in acinar cell necrosis in this model of pancreatitis.

Acute Disease↗
PubMed1978

Isolation and characterization of nascent albuminyl peptides synthesized in vivo from rat liver.

A procedure is described for the isolation of nascent albuminyl peptides from rat liver polysomes which is based on the isolation of total peptidyl tRNA by ion-exchange chromatography on ECTEOLA cellulose followed by immuno-affinity chromatography employing monospecific anti-albumin antibodies immobilized on Sepharose 4B. Identity of the isolated nascent albuminyl peptides was assayed by tryptic peptide fingerprint analysis. Quantitation and determination of the specific activity of the nascent albuminyl peptides, labeled in vivo with l-[14c]leucine, were made by subjecting the peptides to acid hydrolysis, dansylation and resoultion of the amino acids by thin-layer chromatography, and determination of the specific activity of dansyl leucine.

Albumins↗
PubMed1978

Effects of dietary choline and N,N-dimethylaminoethanol on lung phospholipid and surfactant of newborn rats.

Pups delivered by rats fed during pregnancy a choline-deficient (CD) diet containing 1% N,N-dimethylaminoethanol (DME) die within 36 hr of birth. The concentrations of sphingomyelins, phosphatidyl cholines, and disaturated phosphatidyl cholines in the lungs of these pups are lower than those in the lungs of pups delivered by dams fed a choline-supplemented diet (CS). The amount of surfactant isolated from the lung of the pups was also reduced. These changes were accompanied by alterations in the activity of enzymes (choline kinase, EC 2.7.1.32; choline phosphotransferase, EC 2.7.8.2) involved in the synthesis of lung lecithins. These results strongly suggest that pups delivered by dams fed a CD diet containg 1% DME die of respiratory distress syndrome due to altered metabolism of lung surfactant.

Animals↗
PubMed1978

Enhancement of DL-ethionine-induced liver carcinogenesis in rats fed a choline-devoid diet.

The effects of a choline-devoid (CD) or a choline-supplemented (CS) diet on the induction of liver tumors in rats by DL-ethionine were investigated. Groups of male outbred Sprague-Dawley rats were fed a plain CD or a plain CS diet, or the same diets containing 0.05% DL-ethionine. Hepatocellular carcinomas developed in 50% of the rats fed the CD+ethionine diet for 14 weeks and in about 80% of the rats fed the same diet for 22-30 weeks. No hepatocellular carcinomas developed in rats fed the CS+ethionine diet, the plain CD diet, or the plain CS diet up to 30 weeks. The findings suggest that a CD diet alters the response of rat liver to DL-ethionine and leads to an early and enhanced induction of hepatocellular carcinoma.

Animals↗
PubMed1978

Acute hemorrhagic pancreatic necrosis in mice bile acids in gallbladder bile, serum and pancreas.

Mice develop acute hemorrhagic pancreatic necrosis with fat necrosis after 4 days of feeding on a choline deficient-ethionine supplemented (CDE) diet. The diameter, weight and histopathology of the gallbladder were determined in mice fed laboratory chow (LC), a choline-supplemented (CS) diet, a choline-deficient (CD) diet, or the CDE diet for 1, 2 or 3 days. A progressive distension of the gallbladder due to accumulation of bile, was observed in mice fed the CS, CD and CDE diets. An analysis of the bile acid composition of the pancreas, serum and gallbladder bile of mice fed the same diets for 3 days was performed. No differences between control and experimental animals were seen in the concentration and distribution of bile acids in the pancreas. It is concluded that: 1) alterations in bile acid constituents are produced by the diets; and, 2) regurgitation of bile into the pancreas of mice fed the CDE diet does not occur. Thus, bile acids do not seem to initiate or participate in the extensive cellular damage that precedes and accompanies the onset of acute hemorrhagic pancreatic necrosis with fat necrosis in mice fed the CDE diet.

Animals↗
PubMed1978

Early histological and functional alterations of ethionine liver carcinogenesis in rats fed a choline-deficient diet.

The effects of feeding a choline-deficient (CD) or a choline-supplemented diet upon the early stages of DL-ethionine carcinogenesis in rat liver were investigated. Low levels of DL-ethionine (0.05 and 0.10%) when fed with a CD diet were found to induce within 4 weeks a massive proliferation of oval cells without significant cell necrosis or presence of inflammatory cell infiltrates. The same levels of ethionine when fed with a choline-supplemented diet caused no significant histological alteration of the liver. In rats fed the CD plus ethionine diets concomitant with the proliferation of oval cells, there was a marked elevation in the content of alpha1-fetoprotein in both liver and plasma. After specific immunofluorescence staining, oval cells stained intensely for albumin and alpha1-fetoprotein. Hepatocytes stained only for albumin, and bile duct cells stained for neither albumin nor alpha1-fetoprotein. These results indicate that a diet deficient in choline markedly alters the response of rat liver to carcinogenetic doses of ethionine. Thus, ethionine hepatocarcinogenesis in rats fed a CD diet may be a useful model for the exploration of the mechanism(s) whereby a dietary factor influences hepatocarcinogenesis.

Alanine Transaminase↗
PubMed1977

Method for the isolation of surfactant from homogenates and lavages of lung of adult, newborn, and fetal rats.

A method is presented for the isolation of pulmonary surfactant from rat lung homogenates and lavages using differential discontinuous density gradient centrifugation. The isolated surfactant was characterized by electron microscopy, assay of enzyme markers for different subcellular organelles, and its chemical composition. Surfactant that was isolated from lung homogenates appeared to be free of other contaminating cellular organelles. Electron microscopic examination of surfactant isolated from whole homogenates showed the presence of lamellar bodies and tubular myelin figures and, hence, represented total lung surfactant. On the other hand, surfactant prepared from lung lavages had mostly tubular myelin figures and, thus, represented extracellular surfactant. Both preparations were rich in phospholipids, especially lecithins and phosphatidylglycerol, and showed high phospholipid to protein ratios. The method was used to study the quantity and composition of surfactant during lung development in rats. Surfactant was isolated from lung homogenates of fetuses at days 19 to 21 of gestation and from newborn and adult rats. During the period of 19 to 21 days of gestation, there is a 10- and 20-fold increase in the amount of protein- and phospholipids (milligrams per gram of wet lung), respectively. A further 2-fold increase occurs after birth. Phosphatidylcholines account for 65% of the total phospholipids at day 20, 71% on day 21, and 81% at term. A progressive increase in the phosphatidylcholine to sphingomyelin ratios and in the amount of phosphatidylglycerol occurs during this period. The amount of disaturated lecithins (expressed as percentage of total phosphatidylcholines) in the lung surfactant increases from 49% at day 20 to 53% at birth. There is no change in the amount of disaturated lecithins after the newborn stage. The present method for the isolation of lung surfactant is reproducible, is less time consuming, and can be used to isolate quantitatively surfactant from small lung aliquots.

Age Factors↗
PubMed1976

Stimulation of antibody synthesizing lymphocytes in the rat by antigen reactive cells sensitized in vitro.

Lymphocytes obtained from rat spleens were sensitized in vitro to sheep erythrocytes. The sensitized lymphocytes did not synthesize antibody but when injected into unimmunized rats did stimulate antibody production to sheep erythrocytes. Analysis of the location of 7 and 19 S plaque-forming cells in the recipient rats indicated that these two antibody synthesizing cell populations arise from different lymphocytes. It was also found that the sensitized lymphocytes could react only with a limited number of antibody synthesizing cells.

Animals↗
PubMed1976

Acute hemorrhagic pancreatic necrosis in mice. Intraparenchymal activation of zymogens, and other enzyme changes in pancreas and serum.

A new experimental model has been found whereby acute hemorrhagic pancreatic necrosis with fat necrosis is induced in 100% of young female mice fed a choline-deficient diet supplemented with 0.5% DL-ethioine. The onset of the pancreatic necrosis has been shown to follow accumulation, and subsequent activation, of pancreatic zymogens with intraparenchymal formation of significant amounts of elastase, chymotrypsin, and trypsin. Evidence was obtained that the proteolytic enzymes are released also in the circulation and cause a significant drop in the content of the serum protease inhibition alpha 1-antitrypsin and alpha2-macroglobulin. Increased levels of plasma amylase were found to accompany the onset of the pancreatic necrosis.

Acute Disease↗
PubMed1976

Influence of dietary factors on the pancreatotoxicity of ethionine.

Choline deficiency enhances greatly the pancreatotoxicity of DL-ethionine. Mice fed DL-ethionine with a choline-deficient diet develop a fatal acute hemorrhagic pancreatic necrosis with fat necrosis (AHPN) in 5 days. Induction of the AHPN is completely prevented by dietary methionine and drastically reduced by dietary methionine and drastically reduced by dietary choline. The amount of proteins, carbohydrates, and fat in the diet influences its consumption by the animals and thus the severity of the pancreatic pathology. The histogenesis of the process is characterized by widespread alterations of the membranous organelles of the acinar cells, especially the endoplasmic reticulum and the zymogen granules. The onset of the hemorrhagic necrosis of the pancreas is due to an endogenous intraparenchymal activation of the zymogenic proteases, including proelastase. The new experimental model of AHPN appears to mimic very closely the clinical course, the anatomic pathologic lesions, and the postulated pathogenesis of the corresponding human disease.

Acute Disease↗
PubMed1975

Reduced response to phenobarbital by the liver of rats fed a choline-deficient diet.

1. The response of the liver to phenobarbital administration was compared in rats fed either laboratory chow, a semipurified choline-supplemented diet or a semipurified choline-deficient diet. 2. The liver contents of proteins, lipids and cytochrome P-450, as well as the activity of aminopyrine and ethylmorphine demethylases, were measured after 5 days of feeding and five daily injections of phenobarbital. Liver sections were examined electron microscopically. 3. In rats fed the choline-supplemented diet, phenobarbital administration caused increases in cellular constituents, enzyme activities and smooth endoplasmic reticulum membranes as great as those seen in rats fed laboratory chow. However, in rats fed the choline-deficient diet, the response of the liver to phenobarbital administration was severely reduced in comparison to that in rats fed the other diets. 4. It is concluded that dietary choline and an adequate synthesis of lecithins are necessary for the induction of microsomal mixed-function oxidases and the concomitant accumulation of smooth endoplasmic reticulum in hepatocytes.

Animals↗
PubMed1975

Acute hemorrhagic pancreatitis (massive necrosis) with fat necrosis induced in mice by DL-ethionine fed with a choline-deficient diet.

Female, albino mice were fed a choline-deficient diet containing 0.5% DL-ethionine. All animals died within 5 days due to the development of an acute hemorrhagic pancreatis with fat necrosis throughout the peritoneal cavity. The apancreatitis was characterized by a massive necrosis of the exocrine parenchyma with intense hemorrhage and inflammatory reaction of the stroma. The sequence of histologic and ultrastructural alterations occurring in the acinar cells of the pancreas were studied in mice fed the diet for 1, 2, and 3 days. Major findings consited of accumulation of zymogen granules, vacuolation due to foci of cytoplasmic degradation, and alterations in the morphology of the zymogen granules. The pancreatitis appears to be due to intraparenchymal activation of zymogens, resulting from a synergistic action of choline deficiency with the basic toxicity of ethionine toward the acinar cells of the pancreas. The experimental model simulates closely the acute hemorrhagic pancreatitis with fat necrosis occurring in humans and may prove useful for exploring the pathogenesis of this condition.

Acute Disease↗
PubMed1975

Acute hemorrhagic pancreatic necrosis in mice. Influence of the age and sex of the animals and of dietary ethionine, choline, methionine, and adenine sulfate.

The influence of several factors on the development of acute hemorrhagic pancreatitis (pancreatic necrosis) with fat necrosis in mice fed DL-ethionine with a choline-deficient diet has been investigated. The results showed that: a) the incidence of the induced disease is dependent upon the age and sex of the animals and the dietary level of ethionine; b) 100% of young female mice fed 0.5% ethionine develop acute hemorrhagic pancreatitis and die within 5 days; c) the incidence is only 10 to 20% when 0.5% ethionine is fed with either a choline-supplemented diet or with laboratory chow; and d) development of pancreatic pathology is completely prevented by the inclusion in the diet of 0.5% methionine but not by the inclusion of 0.5% adenine. Possible mechanisms whereby choline deficiency potentiates the pancreatotoxicity of ethionine in mice are discussed.

Acute Disease↗