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Biomedical subjects

E Federico

Publications and source records attributed to E Federico.

18 recordsLinked to original sources
PubMed2000

Endotoxin priming and liver damage by experimental duodenal obstruction in the rat.

To verify whether endotoxin (LPS) might act as a priming cofactor of liver injury caused by obstructing the duodenum, four groups of male Wistar rats were studied. The first two groups comprised rats in which a closed duodenal loop (CDL) was created: CDL, n = 6 and CDL + LPS, n = 7; the next two groups comprised sham-operated animals: Sham n = 6 and Sham + LPS, n = 6. LPS, 400 microg/kg bodyweight, was administered i.p. to the rats belonging to groups CDL + LPS and Sham + LPS, 24 h before laparotomy. Twenty-four hours after laparotomy the animals were killed. Damage to bile ducts, extent and grading of coagulative and lytic spotty necrosis in liver tissue were evaluated morphologically. Coagulative necrosis was severe in four of seven rats of the group CDL + LPS, mild in six of six rats of group CDL, and absent in four of six and five of six rats of groups Sham and Sham + LPS (chi2 32.8, P = 0.0001). The animals of group CDL + LPS had more frequently diffuse lytic spotty necrosis than the animals in the three other groups (chi2 9.57 P<0.01). The results of our study indicate that, in rodents subjected to a closed duodenal loop, priming with LPS exacerbates liver injury due to cholate stasis.

Alanine Transaminase↗
PubMed2000

Evaluation of circulating activin-A as a serum marker of hepatocellular carcinoma.

Because in experimental hepatocarcinogenesis apoptosis increases from normal to preneoplastic to carcinoma tissue, proapoptotic factors, such as activin-A, may represent useful markers for hepatocellular carcinoma (HCC). In this study, serum activin-A was measured in 99 cirrhotic patients, of whom 55 had HCC. Activin-A concentrations were higher in HCC patients (median, 2.33 ng/ml; range, 0.41-8.12) than in patients with nonmalignant cirrhosis (1.28 ng/ml; range, 0.35-6.25) (P < .05). All 12 patients with activin-A greater than 3 ng/ml and serum alpha-fetoprotein greater than 30 ng/ml had HCC, in comparison to 32 of 41 patients who had only one and to 11 of 46 patients who had both markers below these cutoffs (P < .0001). No correlation was found between activin-A and alpha-fetoprotein in the two groups, whereas in patients with HCC, activin-A was strictly correlated with serum aspartate aminotransferase (P < .001). Activin-A mRNA for inhibin betaA subunit was expressed both in tumor and nontumor liver tissues in a case of HCC superimposed on cirrhosis and was not expressed in a case of HCC without cirrhosis. In conclusion, cirrhotic patients with HCC have high serum activin-A, to the production of which both the cirrhotic liver and the liver tumor are likely to contribute.

Activins↗
PubMed1999

Effect of eating on plasma radical-trapping antioxidant activity (TRAP) in patients with cirrhosis.

OBJECTIVES: To ascertain the effects of eating on plasma antioxidant capacity in patients with liver disease. DESIGN AND METHODS: Eighteen cirrhotic patients were compared to 18 age and sex-matched controls. TRAP was measured by a fluorometric assay after a 12 h fast, and 60, 120, and 180 min after the study participants had taken a drink formula food. RESULTS: In the fasting state, TRAP was higher in patients with alcoholic cirrhosis (847+/-39 micromol/L, mean +/- SEM) in comparison to patients with viral cirrhosis (653+/-41) and to controls (758+/-26) (p<0.005). In cirrhotic patients, TRAP did not change in the post-absorptive state. In controls, TRAP decreased progressively, to a value of 719+/-21 (p<0.02), and the AUC of the delta-values of TRAP and of plasma insulin showed an inverse correlation (r = -0.52, p<0.05). CONCLUSIONS: In normal subjects, but not in cirrhotics, TRAP decreases in the post-absorptive state, probably in relationship with the activation of metabolic pathways.

Antioxidants↗
PubMed1999

Tubular reabsorption and sodium excretion during urine reinfusion.

BACKGROUND: The mechanisms responsible for the natriuresis that follows urine reinfusion was investigated in rats by clearance and micropuncture techniques. METHODS: In each animal two urine reinfusion periods (R1 and R2) were performed and compared to a non-urine-reinfusion, saline infusion period (S) sandwiched between them. RESULTS: Switching from urine reinfusion to an equivalent rate of saline loading was followed by a fall in Na excretion from 1.9 +/- 0.5 to 0.5 +/- 0.2% of filtered load, p < 0.002. Urine osmolality rose, and urine to plasma inulin concentration ratio rose significantly from 73 +/- 14 to 147 +/- 21 (p < 0.002). The changes in GFR, SNGFR, absolute and percent proximal reabsorption could not account for these findings. A reduced Na excretion coupled to increased urine osmolality indicates enhanced transport along a segment responsible for the urinary concentrating mechanism. Thus the data can be interpreted then as due to enhanced reabsorption along the ascending limb of Henle's loop. These changes were reversed by reinstituting urine reinfusion after the S period. The consensual changes in Na+ and K+ excretion excluded an effect of urine reinfusion on the distal exchange site. There was a continuous fall in proximal reabsorption from R1 (76 +/- 3%) to S (69 +/- 3%) to R2 (62 +/- 5%) which was inversely correlated with the changes in hematocrit (R = 0.49, p < 0.026). This indicates that part of the late diuresis and natriuresis was due to volume expansion. An osmotic effect of reinfused urine solutes was suggested by a late rise in plasma osmolality, from 312 +/- 13 to 323 +/- 8 mOsm/kg. Osmotic diuresis could have exerted additive effects upon those of volume expansion, accounting for the late fall in proximal reabsorption. CONCLUSIONS: We conclude that the acute effects of urine reinfusion are due to changes in transport of solutes and permeability to water along distal tubular segments. The changes in plasma osmolality during the last period of the present acute experiments, suggest the possibility that solute retention may be linked to the chronic effects of urine reinfusion.

Animals↗
PubMed1998

The site of action of furosemide.

To establish whether furosemide (F) acts on the proximal tubule beside the thick ascending limb of Henle's loop, we reviewed the data from 55 rats studied before and during the i.v. infusion of 10 mg kg-1 of furosemide. These animals were the object of previously published studies. SNGFR was 42.6+/-1.1 nl min-1 during baseline conditions (B), 42.7 nl min-1 during F (P>0.9). In 151 paired last proximal tubular samples, percentage reabsorption was 71.72 before and 71.72% after F (P=1.0). In 64 paired early distal tubular samples, percent reabsorption fell from 86% in B to 78% during F (P<0.0001). During F, the urine flow rate expressed as a percentage of GFR (24+/-2%) was significantly correlated (R=0.52, P<0.0001) with the percent delivery of filtrate out of the proximal tubule (26+/-3%). These data demonstrate that, even at this very high dosage, F does not act on the proximal tubule. It inhibits transport on the ascending limb of Henle's loop. By allowing the delivery of isotonic tubular fluid to the distal tubule, it causes a fall in volume absorption along the early distal convolution in proportion to its baseline water permeability. It increases urine flow by abolishing the interstitial hypertonicity and, consequently, the osmotically driven solvent flow across the distal epithelium and collecting ducts. Therefore the urine flow rate during F closely approximates volume delivery out of the proximal tubule.

Animals↗
PubMed1998

The effect of reducing proximal tubular fluid delivery on the rate of filtration of single nephrons.

The rate of delivery of tubular fluid from the proximal tubule (PT) is thought to reset nephron filtration rate (SNGFR). In micropuncture experiments in rats we tested this hypothesis by reducing the efflux from the PT by simultaneously "double collecting" (DC) tubular fluid from the early distal tubule (DT) and from the last convolution of the PT of the same nephrons. SNGFR measured by total collection of tubular fluid was 34 +/- 3 nl/min at the DT and 34 +/- 3 nl/min at the PT (p > 0.97, n = 42). The simultaneous collection from proximal and distal sampling site was performed between these two paired measurements. It yielded an average SNGFR of 40 +/- 3 nl/min (p < 0.02). This may be due to the collection, at the distal site, of the extra amount of inulin stored between distal and proximal pipette, prior to starting the aspiration of tubular fluid. Since this error would decrease in longer collections, the difference in SNGFR between single and double collections was plotted against the duration of collections. In fact it was negatively correlated with the sampling time (p < 0.01), indicating no difference in SNGFRs for collections > 4 minutes. Reduction and complete interruption of the delivery of native proximal tubular fluid to the Macula Densa does not seem to influence the measurement of SNGFR. Filtration rate is not significantly different when measured within few minutes at the DT and PT of the same nephrons.

Animals↗
PubMed1998

Relationship among hepatic inflammatory changes, circulating levels of cytokines, and response to IFN-alpha in chronic hepatitis C.

To investigate the relationship among circulating cytokines, inflammation in the liver, and kind of response to interferon-alpha (IFN-alpha) in hepatitis C, we studied 63 consecutive patients (38 male, 25 female), treated with IFN for up to 1 year. Serum tumor necrosis factor-alpha (TNF-alpha) was measured at baseline and after 3 months of treatment. Transient (TR) or sustained response (SR) was observed in 29 and 16 patients, respectively. Baseline levels of TNF < or = 22 ng/L were observed in 69% of patients with SR, 55% of patients with TR, and 22% of nonresponders (p < 0.01). There was a significant correlation between baseline TNF levels and histologic grading score of hepatitis (p < 0.01). After 3 months of treatment, TNF levels >22 ng/L were observed in 63% of patients with SR, 69% of patients with TR, and 83% of nonresponders (p NS). Independent of the treatment outcome, TNF levels were lower at baseline and increased significantly with treatment in patients with lower histologic grading (p < 0.005). In conclusion, in patients with chronic hepatitis C, circulating TNF levels correlate with the degree of inflammation in the liver. Response to IFN is accompanied by an inflammatory response involving the release of TNF.

Adult↗
PubMed1997

Blood lipids of patients with chronic hepatitis: differences related to viral etiology.

In order to investigate whether a difference might exist in blood cholesterol and its subtractions between patients with chronic hepatitis B virus (HBV) or hepatitis C virus (HCV) infection, serum cholesterol, HDL-cholesterol, triglycerides and common liver function tests were measured in 138 patients (92 male, 46 female) with biopsy-proven chronic viral hepatitis without cirrhosis. Twenty-four had hepatitis B and 114 hepatitis C. Mean serum cholesterol was lower in HCV-infected in comparison to HBV-infected patients (175 +/- 36 mg/dl vs. 189 +/- 28 mg/dl, p < 0.05). On multivariate analysis, etiology of hepatitis appeared to be associated with the value of serum cholesterol, independently of age, sex and liver synthetic function (improvement of chi-square 4.40, p < 0.05). In patients with HBV infection, circulating tumor necrosis factor-alpha demonstrated a correlation with serum triglycerides (p = 0.618) and an inverse correlation with serum HDL-cholesterol (p = -0.456); in the group of patients with HCV infection, interleukin-6 correlated with triglycerides (p = 0.370) and HDL-cholesterol (p = -0.355). Thus, differences in the mechanisms of liver damage and of viral clearance in hepatitis C in comparison to hepatitis B, reflected in these patients by the levels of circulating cytokines, may be mirrored by differences in their blood lipid composition.

Adult↗
PubMed1997

The validity of the recollection technique in micropuncture experiments on the rat kidney.

We tested the accuracy of the micropuncture technique by performing total collections of tubular fluid followed by immediate recollections from the same site. We studied thirty-one Wistar rats under different conditions of hydration and during maintenance infusions. To assure constancy of body fluid volumes the experiments were performed during continuous reinfusion of urine. Overall we performed 190 paired collections and immediate recollections from 147 proximal and 43 distal tubules. The mean values measured during the first collection were not different from the paired means obtained by recollection. Mean values (+/- S.E.M.) for first collection and recollection were: single nephron glomerular filtration rate (SNGFR), 34.7 +/- 1.3 vs. 34.2 +/- 1.3 nl min-1, P > 0.42; percentage reabsorption, 74 +/- 1 vs. 73 +/- 1, P > 0.53; absolute reabsorption, 26.4 +/- 1.2 vs. 25.9 +/- 1.2 nl min-1, P > 0.47; collection rate, 8.4 +/- 0.6 vs. 8.3 +/- 0.4 nl min-1, P > 0.92. When subdivided according to different physiological conditions and sampling sites, the results for the paired collection-recollection means were still not significantly different. The regression between collected and recollected SNGFRs had a slope of 0.96, r = 0.85, P < 0.0001. In order to exclude the possibility that urine reinfusion per se could obscure putative differences in collection-recollection pairs, the effect of urine reinfusion was separately evaluated. We measured the differences obtained in collection-recollection pairs before and during urine reinfusion in twenty-eight tubules from eleven rats, a sample size that allows the detection of 10% difference as significant. While SNGFR did not change, percentage reabsorption fell significantly from 76 +/- 3% before infusion to 60 +/- 3% during reinfusion, P < 0.003. We conclude that the recollection technique yields a reproducible estimate of SNGFR and tubular reabsorption, independent of the sampling site and of the technique used for fluid maintenance. Thus, it can be used to study the effect of different manoeuvres on the rate of proximal tubular transport. Urine infusion per se depresses proximal transport compared with that measured during maintenance with equivalent amounts of isotonic saline.

Animals↗
PubMed1997

Microinjection studies on the effect of furosemide on the rat nephron.

The tubular site of furosemide (F) action was studied by the technique of diuretic microinjection (MIJ) into proximal tubules of the rat nephron. F was injected into the last proximal superficial loop of 51 proximal tubules, at the concentration of 3 x 10(-4) mol/l in an infusate that contained 14C-inulin. Collections were performed at the early distal tubule before and after MIJ. Single nephron filtration rate (SNGFR) remained unchanged, while the percent of filtered volume reabsorbed up to the site of collection was 85+/-2 before, 79+/-2% after MIJ, p < 0.005. The calculated concentration of F in the collected distal tubular fluid during the post-MIJ measurements averaged 3 x 10(-5) mol/l. This experiment was repeated by injecting F into the early proximal convolutions of 43 nephrons, while the collections were performed at the last proximal segments. In these studies of proximal volume absorption, SNGFR was 34+/-3 before, 35+/-4 nl/min after F (p > 0.6). The respective percent reabsorptions were 70+/-3 and 73+/-3% (p +/- 0.3). In order to determine whether the technique per se was suitable to detect changes in reabsorption, the proximal MIJ study was repeated by using the carbonic anhydrase inhibitor dichlorphenamide 3 x 10(-5) mol/l in the microinjectate: while SNGFR remained unchanged, percent reabsorption fell from 63+/-5 to 45+/-7% during injection of the diuretic, p < 0.03. We conclude that the technique is adequate to examine the effects of drugs, and that F does not reduce proximal volume absorption at concentrations of 3 x 10(-5) mol/l. The loop diuretic decreases distal volume absorption by abolishing the osmotic gradient between blood and tubular fluid along the early distal convoluted tubule.

Animals↗
PubMed1997

A comparison of four serum markers of fibrosis in the diagnosis of cirrhosis.

C-terminal peptide of procollagen I, N-terminal peptide of procollagen III, collagen IV and serum prolyl hydroxylase were measured in 100 patients with cirrhosis and 71 patients with noncirrhotic chronic liver disease. Patients with cirrhosis had significantly higher mean values of prolyl hydroxylase, collagen IV, N-terminal peptide of procollagen III and C-terminal peptide of procollagen I as compared to noncirrhotic patients. This difference was maintained for collagen products even after stratification for alcohol intake, although all markers of fibrosis were higher in alcoholics. Stepwise logistic regression analysis showed that collagen IV, and N-terminal peptide of procollagen III were independently associated with cirrhosis. Receiver-operating characteristic (ROC) curves showed that collagen IV and N-terminal peptide of procollagen III perform more efficiently than C-terminal peptide of procollagen I and prolyl hydroxylase in identifying cirrhosis.

Adult↗
PubMed1996

Endotoxin priming exacerbates acute reflux pancreatitis in the rat.

Recently, endotoxaemia has been reported as a prognostic marker in acute pancreatitis. However, the role of endotoxin in inducing or aggravating acute pancreatitis is not fully understood. We administered endotoxin 400 micrograms/kg i.p. to rats 24 h before performing either a closed duodenal loop (group B) or a sham operation (group D). Pancreatic damage and overall survival were compared with the results obtained in rats not exposed to endotoxin undergoing either closed duodenal loop (group A) or sham treatment (group C). In a first set of experiments, 24 h after laparotomy blood samples were collected and the animals were sacrificed; survival up to 8 days was estimated in a second set of experiments. Group B had higher lipase concentrations and more severe tissue damage than group C (P < 0.05). A larger number of abscesses was observed in both group B and group D as compared to group C (P < 0.05). Survival was significantly shorter in group B (P < 0.0001). We conclude that priming with endotoxin worsens the extent of pancreatic damage induced by the closed duodenal loop procedure in the rat, possibly favouring selective homing of neutrophils to the site of inflammation, in similarity to what happens in the Shwartzman phenomenon.

Animals↗
PubMed1996

The effect of intraluminal flow rate on glomerulotubular balance in the proximal tubule of the rat kidney.

To differentiate intraluminal from peritubular factors in mediating the glomerulotubular balance, single nephron filtration rate (SNGFR) and reabsorption were measured by total collection from the last proximal segment before, and during, externally applied mechanical compression of an early proximal convolution of ninety-three rat nephrons. SNGFR fell from 55.6 +/- 2.3 nl min-1 during control conditions to 34.5 +/- 2.0 nl min-1 during compression (P < 0.0001) in sixty tubules ('responders'). Absolute reabsorption fell from 41.8 +/- 2.0 to 28.4 +/- 1.8 nl min-1 (P < 0.0001), while percentage reabsorption rose from 75 +/- 2 to 82 +/- 2% (P < 0.0001). These effects were reversible and independent of whether the compression was applied before or after the control collection. In thirty-three proximal tubules the compression procedure was not successful ('non-responders'), SNGFR remaining unchanged (36.1 +/- 2.9 vs. 36.9 +/- 2.9 nl min-1, P > 0.3). Absolute and percentage reabsorptions rose slightly, albeit significantly, from 26.1 +/- 2.1 to 30.7 +/- 2.4 nl min-1 (P < 0.0001) and from 75 +/- 3 to 85 +/- 2% (P < 0.0001). Thus, the response of reabsorption to changes in intraluminal flow is composed of two different adaptive mechanisms. The slowing of flow is present in both sets of tubules and causes a slight increase in resorption; the change in filtration per se is present only in the first set of responders, and causes an SNGFR-dependent consensual change in resorption.

Absorption↗
PubMedDate not supplied

Diet composition, alcohol utilization, and dependence.

Experiments were carried out in which a nutritionally balanced liquid diet previously used in this laboratory was modified as to total calorie content and high or low carbohydrate and fat concentration. Ethanol was added at 4.5% and 6.2% of diet weight and provided either 27% or 34-37% of total calories depending upon the changes in nutrient content. Measurements included 8-day food/calorie and ethanol consumption, plasma ethanol level, liver alcohol dehydrogenase (ADH) activity, and rate of audiogenic-induced withdrawal seizures. The original liquid diet with 4.5% ethanol was consumed in significantly lesser amounts than the alcohol-free diet, and essentially no body weight gain occurred, regardless if the major nonalcohol, nonprotein calorie source was fat or carbohydrate. When the calorie content of the diet was boosted through the addition of extra carbohydrate or fat (at the expense of water), appreciable weight gain was noted; in the case of the higher calorie diet boosted with more carbohydrate (maltodextrin) calories, growth was similar to that observed on the alcohol-free control diet. On this latter diet ethanol calories appeared to be utilized close to their theoretical value of 7 kcal/g. Blood alcohol levels were significantly higher on the lower calorie diets and were lowest on the high-calorie, high-carbohydrate, 4.5% ethanol diet. This diet also allowed for the lowest rate of withdrawal seizures despite an ethanol intake that was as high as on the lower calorie diets. Essentially, no differences were noted among ADH activities for the dietary treatments studied and thus, did not explain the differences observed among blood ethanol levels. When the alcohol concentration in the high-carbohydrate, high-calorie diet was raised to 6.2% from 4.5% to provide 34% of total calories, the rats responded by decreasing their food (and alcohol) intake to the same level as did the animals receiving a much lower calorie diet, but with 37% of caloric alcohol content. This suggests that at a diet alcohol concentration of 34-37%, one or more nutrient metabolites become limiting in the utilization of ethanol, resulting in food intake adjustments that maintain similar amounts of alcohol consumption.

Alcohol Drinking↗
PubMedDate not supplied

Measurement of nephron filtration from distal and proximal tubules.

Nephron filtration rate (SNGFR), measured proximally by micropuncture using the technique of total collection of tubular fluid, may be spuriously high as the fall in intratubular pressure during collection may increase the net filtration pressure. Alternatively, the interrupted distal delivery of tubular fluid during proximal collection may up-regulate SNGFR by activating the tubulo-glomerular feedback. The accuracy of nephron filtration measurements was tested in 65 rats, by sampling from the distal and then from the proximal tubule of the same nephrons. Collections were also made in the presence of high concentrations of furosemide at the dose of 10 mg/kg i.v. In 290 nephrons, distal SNGFR was not significantly different from the paired measurements obtained from the proximal tubule (39+/-1 vs 39+/-1 nl/min, p > 0.83). During furosemide, the paired data were 42+/-2 vs 41+/-2 nl/min, p > 0.82, n=92. Different hydration conditions did not influence the results. The correlation between distally and proximally measured filtration rates held for the whole range of measurements (R=0.56; p < 0.0001). Under the present experimental conditions, SNGFR is not spuriously high when measured by total blockade of the proximal tubule. The accuracy of measurements and their reproducibility is not influenced by the site of sampling.

Animals↗