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Biomedical subjects

R Lenzi

Publications and source records attributed to R Lenzi.

At least 55 records · Page 3Linked to original sources
PubMed1992

Aging on the waiting list: should it be a further criterion for cadaver kidney allocation?

Transplant recipients have been selected from our dialysis patients mainly according to the criteria of the best HLA match and the best clinical condition. We have observed that, in using these criteria, most of the patients who receive transplants in the first 2 years on the waiting list. The other patients remain on the waiting list with progressively less chance of transplantation due to a deterioration of their clinical condition and the related increase in risk factors.

Age Factors↗
PubMed1992

Histogenesis of bile duct-like cells proliferating during ethionine hepatocarcinogenesis. Evidence for a biliary epithelial nature of oval cells.

The origin of bile duct-like cells (oval cells) proliferating during chemical hepatocarcinogenesis is highly controversial. To illuminate this issue, we induced oval cell proliferation by feeding rats a choline-devoid diet containing 0.1% ethionine (CDE), a hepatocarcinogenic diet, for up to 60 days. At various times we studied 1) oval cell morphology by light and electron microscopy, 2) the immunohistochemical expression of albumin and intermediate filament proteins by the various hepatic cells, 3) hepatic incorporation of [3H]thymidine by histoautoradiography, 4) the fractional area occupied by duct-like structures in liver cross sections, 5) the biliary tree volume in vivo to establish the possible continuity of the proliferated structures to the existing biliary lumina, and 6) spontaneous bile flow rate and the choleretic responsiveness to the hormone secretin, which stimulates ductular secretory activity. The results demonstrated the following: 1) oval cells resemble bile duct cells with respect to their histologic and ultrastructural appearance and their formation of duct-like structures; 2) as normal and hyperplastic bile duct cells induced by bile duct ligation, oval cells are positive for cytokeratins 7 and 19 (markers of glandular epithelia) and 8 and 18 (markers of simple epithelia) and are negative for vimentin and desmin, markers of mesenchymal and muscular differentiation, respectively; 3) in general, oval cells are negative for albumin, which is expressive of hepatocyte lineage, even though a few are positive for this protein, particularly those morphologically resembling small hepatocytes; 4) after initiation of the CDE diet, DNA synthesis begins in biliary epithelial cells; and 5) the degree of oval cell proliferation parallels the increase in biliary tree volume, spontaneous bile flow rate, and responsiveness to secretin choleresis, as in bile duct cell hyperplasia induced by biliary obstruction. Although the involvement of a periductular progenitor compartment cannot entirely be eliminated, these findings are construed to indicate that oval cells proliferating during CDE hepatocarcinogenesis are biliary epithelial cells. In our view, oval cells represent the two-dimensional expression of spatially expanded cholangioles and intrahepatic bile ductules and/or ducts.

Animals↗
PubMed1991

Distribution of glucose-6-phosphatase activity in normal, hyperplastic, and preneoplastic rat liver.

The significance of glucose-6-phosphatase (G6P) expression by bile duct-like cells proliferating during hepatocarcinogenesis in the histogenesis of hepatocellular carcinoma is not clear. To this end, we measured the histochemical and biochemical activity of G6P in normal rat liver, and in rat livers in which bile duct-like proliferation was induced by either hyperplastic (bile duct ligation for 14 days or feeding alpha-naphthylisothiocyanate for 28 days) or neoplastic (feeding a choline-devoid diet containing 0.1% ethionine for 60 days) regimens. In normal, hyperplastic, and preneoplastic livers, G6P histochemical activity was confined to the hepatocytes; proliferated bile duct-like cells, like normal bile ducts, did not display visible G6P staining. When the enzyme activity was determined biochemically, however, hydrolysis of glucose-6-phosphate was observed in both parenchymal and nonparenchymal liver cells isolated from all experimental animals. In elutriated nonparenchymal fractions, G6P activity was directly proportional to the number of cells positive for gamma-glutamyl transpeptidase and cytokeratin no. 19 (markers of bile duct cells) and inversely proportional to the number of cells positive for vimentin (marker of mesenchymal cells). These results indicate that, while by light microscopy hepatic G6P histochemical activity is detectable only in the hepatocytes, the biochemical activity is also expressed in proliferating bile duct-like cells. However, the nonparenchymal activity is observed during both neoplastic and hyperplastic liver growth, thus indicating that the presence of this enzyme in bile duct-like cells proliferating during hepatocarcinogenesis should not necessarily be construed as supporting their stem cell nature nor their neoplastic commitment.

1-Naphthylisothiocyanate↗
PubMed1990

von Willebrand factor antigen is not an accurate marker of rat and guinea pig liver endothelial cells.

To determine whether von Willebrand Factor (vWF) is a valid marker of liver endothelial cells, we determined vWF immunoreactivity in rat and guinea pig liver sections and in smears of elutriated nonparenchymal cells isolated from these two species. In frozen sections, positive staining for vWF was seen only in the endothelium lining large hepatic vessels in both species, and no immunoactivity was detected in the sinusoids. On the other hand, immunohistochemical staining for vimentin (a marker of mesenchymal cells) showed positive reaction throughout the vascular and sinusoidal endothelial cells in both the rat and guinea pig liver. In fractions of elutriated rat and guinea pig nonparenchymal liver cells, which included almost exclusively liver endothelial cells, only 25-40% of the cells displayed a positive reaction for vWF. However, when these same fractions were stained for vimentin, 70-95% of the cells exhibited immunoreactivity. Most of the vWF-negative cells were not red and white blood cells, biliary epithelial and Kupffer cells, and hepatocytes, and had ultrastructural features of sinusoidal endothelial cells. We conclude that in both the rat and guinea pig, liver sinusoidal endothelial cells do not exhibit vWF immunoreactivity. Thus, in routine immunohistochemical assays, vWF is not an accurate marker of rat and guinea pig liver endothelial cells. Vimentin is more appropriate for this purpose, provided that other mesenchymal cells are separated or independently identified.

Animals↗
PubMed1989

Isolation of a nonparenchymal liver cell fraction enriched in cells with biliary epithelial phenotypes.

In the present study we have isolated and purified fractions of nonparenchymal liver cells were isolated by collagenase-pronase digestion of the biliary and connective hepatic tissue, which remained undissociated after collagenase perfusion of the liver. Fractionation of the nonparenchymal fractions was then achieved by centrifugal elutriation. Both normal rats and rats with proliferated bile duct-like structures, which were induced either by a 14-day bile duct ligation or by feeding 0.1% alpha-naphthylisothiocyanate for 28 days, were used in these studies. Using a normal rat liver, the fraction richest in biliary epithelial cells was that obtained at a pump flow rate of 36-40 ml/min. In this fraction 1.8-3.8 x 10(6) cells per liver were recovered and up to 55% of them were positive for gamma-glutamyl transpeptidase and cytokeratins 7 and 19, all of which were histochemically or immunohistochemically detected solely in the biliary structures in the intact rat liver. When the nonparenchymal cells were isolated from hyperplastic livers, the number of cells recovered in such a fraction ranged from 12 to 19 x 10(6) per liver, and as many as 60%-85% of the cells expressed phenotypes of biliary epithelial cells. These results indicate that (a) by centrifugal elutriation a fraction of nonparenchymal cells enriched in cells with biliary epithelial phenotypes can be obtained from rat liver and (b) the hepatic hyperplasia induced by biliary obstruction or alpha- naphthylisothiocyanate feeding is a useful and valid strategy for improving both the yield and the purity of the isolated biliary epithelial cells.

Animals↗
PubMed1989

Bile secretory function of intrahepatic biliary epithelium in the rat.

To shed light on ductular fluid secretion, hepatic histology and ultrastructure, cell proliferation and phenotypes, and several aspects of biliary physiology were studied in rats with ductular cell hyperplasia induced by either biliary obstruction (0-14 days) or 1-naphthylisothiocyanate (ANIT) feeding (0-28 days). In both groups of experimental animals, bile duct hyperplasia and spontaneous bile flow and secretin-induced choleresis increased with time of treatment in a linear fashion. Measurements of [14C]mannitol biliary entry and of biliary tree volume showed that the increase in both spontaneous and secretin-stimulated bile flow originated at the proliferated biliary structures. Ultrastructural examination, [3H]thymidine incorporation, and histochemical and immunohistochemical staining for various markers demonstrated that in both hyperplastic reactions the proliferated cells were the progeny of preexisting biliary epithelial cells and retained their characteristics. These results indicate that the increased bile secretory activity associated with either biliary obstruction or ANIT intoxication reflects a quantitative change due to the proliferation of biliary epithelial cells. Thus both models of bile ductular cell hyperplasia lend themselves to assessment of the transport function of intrahepatic biliary epithelium and its contribution to normal bile formation. In the present studies, we have estimated that net ductular secretion in the normal rat accounts for 10-13% of spontaneously secreted hepatic bile.

1-Naphthylisothiocyanate↗
PubMed1989

[Prolonged use of intravenous nitro derivatives in acute myocardial infarction (AMI)].

A retrospective survey is made on 166 cases of acute myocardial infarction, treated with intravenous nitro-derivatives for eight days of continuous therapy. This therapeutic modality appears to gain four goals: a reduction in mortality of patients, a faster return of ST tract on isoelectric guideline, fewer ventricular pump failures. In the authors' point of view, a delay in the downward return of ST tract towards the isoelectric guideline is an important but ominous prognostic sign in this group of patients. Therefore, this modality of treatment is suggested for all patients with AMI, wherever the myocardial coronary lesion is localized.

Adult↗
PubMed1988

Biliary physiology in rats with bile ductular cell hyperplasia. Evidence for a secretory function of proliferated bile ductules.

To establish the role of the biliary epithelium in bile formation, we studied several aspects of biliary physiology in control rats and in rats with ductular cell hyperplasia induced by a 14-d extrahepatic biliary obstruction. Under steady-state conditions, spontaneous bile flow was far greater in obstructed rats (266.6 +/- 51.9 microliters/min per kg) than in controls (85.6 +/- 10.6 microliters/min per kg), while excretion of 3-hydroxy bile acids was the same in the two groups. Infusion of 10 clinical units (CU)/kg per h secretin produced a minimal choleretic effect in controls (+3.8 +/- 1.9 microliters/min per kg) but a massive increase in bile flow in the obstructed animals (+127.8 +/- 34.9 microliters/min per kg). Secretin choleresis was associated with an increase in bicarbonate biliary concentration and with a decline in [14C]mannitol bile-to-plasma ratio, although solute biliary clearance significantly increased. Conversely, administration of taurocholate (5 mumol/min per kg) produced the same biliary effects in control rats and in rats with proliferated biliary ductules. In the obstructed animals, the biliary tree volume measured during taurocholate choleresis (67.4 +/- 15.8 microliters/g liver) was significantly greater than that determined during the increase in bile flow induced by secretin (39.5 +/- 10.4 microliters/g liver). These studies indicate that, in the rat, the proliferated bile ductules/ducts spontaneously secrete bile and are the site of secretin choleresis. Furthermore, because the proliferated cells expressed phenotypic traits of bile ductular cells, our results suggest that whereas under normal conditions the biliary ductules/ducts in the rat seem to contribute little to bile formation, secretion of water and electrolytes is a property of biliary epithelial cells.

Amylases↗
PubMed1987

Posterior urethroplasty in children.

A series of 33 posterior urethral strictures in children is presented. The etiology was traumatic in 31 cases and iatrogenic in 2. Complex strictures were treated by a transpubic approach (20 cases) or by a posterior scroto-urethral inlay (1 case). Simple strictures were directly treated via the perineum: by a push-in technique (6 cases); by end-to-end anastomosis (3 cases); by a skin pedicled tube urethroplasty (1 case); by free skin graft (1 case), and by endoscopic urethrotomy (1 case). The use of omentum, employed in 19 cases, is considered a necessary step in transpubic urethroplasty. Favorable results were observed in 18 out of 20 transpubic procedures, in 8 out of 9 perineal urethroplasties and in 3 out of 4 other techniques, with an overall success rate of 87.8%.

Adolescent↗
PubMed1987

Urethral trauma: radiological aspects and treatment options.

Experience with treatment of 38 patients in an early phase with urethral trauma is presented. The site of injury was the penile urethra in three cases, the bulbous urethra in seven, and the prostatomembranous urethra in 28. Different surgical procedures were used, according to the site and the extent of urethral damage and the presence of associated lesions. All patients with penile and bulbous urethral trauma were cured and only one has diminished sexual potency, while in the posterior urethral group nine were cured, and 19 developed strictures requiring further surgical treatment. Total impotence developed in 17 and partial impotence in one patient. Another case presents urinary urge incontinence.

Humans↗