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Biomedical subjects

A Manenti

Publications and source records attributed to A Manenti.

At least 19 recordsLinked to original sources
PubMed2001

Antioxidant liposoluble vitamins and carotenoids in chronic hepatitis.

Background: It is known that antioxidant liposoluble vitamins and carotenoids are reduced in liver cirrhosis, but little is known about chronic viral hepatitis, where oxidative damage has to be taken into account. Methods: Fifty-five patients with chronic hepatitis, mainly C virus-related, were matched with 16 patients with biliary stones and 20 healthy controls. Plasma and liver analyses were carried out using a well-tried HPLC technique that affords an accurate quantification of retinol, tocopherol, alpha- and beta-carotene, cryptoxanthin, and lycopene. Results: Plasma concentration of retinol, tocopherol, beta-carotene, and lycopene was significantly decreased in both patient groups, particularly in those with chronic hepatitis. In contrast, liver concentration of both esterified and free retinol, tocopherol, and some carotenoids was better preserved in the hepatitis group than in the cholelithiasis group. A strict correspondence between aminotransferases and the amount of liver-stored retinol was documented. Conclusions: Plasma vitamin and carotenoid depletion co-existing with preserved liver storage may indicate a functional defect in liver pool mobilization or even a real depletion of the antioxidant defenses, which play a key role in averting cellular damage. The implications for nutrition and therapy need to be taken into account.

Journal Article↗
PubMed2001

Suppression of bile acid synthesis, but not of hepatic cholesterol 7alpha-hydroxylase expression, by obstructive cholestasis in humans.

Regulation of bile acid synthesis, a key determinant of cholesterol homeostasis, is still incompletely understood. To elucidate the feedback control exerted on bile acid biosynthesis in humans with obstructive cholestasis, 16 patients with bile duct obstruction were studied. In vivo 7alpha-hydroxylation, reflecting bile acid synthesis, was assayed in 13 of them by tritium release analysis. Serum 27-hydroxycholesterol was determined by gas chromatography-mass spectrometry. In a subgroup, hepatic cholesterol 7alpha-hydroxylase mRNA was assayed by real-time polymerase chain reaction (PCR), enzyme activity was determined by isotope incorporation, and microsomal cholesterol content was assayed by gas chromatography-mass spectrometry. Age-matched control subjects were studied in parallel. Hydroxylation rates were lower in cholestatic patients (108 +/- 33 mg of cholesterol per day, mean +/- SEM; controls: 297 +/- 40 mg/d; P <.01). The reduction was proportional to the severity of cholestasis, and synthetic rates were normalized in 4 subjects restudied after resolution of biliary obstruction. Consistent findings were obtained by analysis of serum 7alpha-hydroxycholesterol levels. On the other hand, hepatic cholesterol 7alpha-hydroxylase mRNA, microsomal enzyme activity, and cholesterol content tended to be increased in cholestasis. Finally, serum 27-hydroxycholesterol levels were slightly reduced in cholestatic subjects and were not related with the severity of the disease. Suppression of in vivo bile acid synthesis with no corresponding reduction in tissue 7alpha-hydroxylase expression and activity is consistent with nontranscriptional, posttranslational levels of regulation; these may play a role in the feedback control of bile acid synthesis in particular conditions. Alteration of the alternate biosynthetic pathway seems unlikely according to the present data.

Aged↗
PubMed1998

Aberrant crypt foci in patients with colorectal cancer.

Aberrant crypt foci (ACF) are clusters of abnormally large colonic crypts identified on the mucosal surface of the human colon. They are thought to be preneoplastic lesions. The aim of the present study was to compare density (number of ACF per square cm of mucosal surface), crypt multiplicity (number of crypts per ACF) and histology of ACF in colonic resections of colorectal cancer patients resident in two Italian provinces with a twofold difference in colorectal cancer incidence rates. Thirty-two and 26 colonic resections were collected after operation in Ragusa (Southern Italy) and Modena (Northern Italy), respectively, and fixed in 10% formalin. Mucosal layers were observed under a light microscope at 25x after staining with methylene blue. Density of ACF was significantly higher in Modena (median 0.101 ACF cm(-2)) than in Ragusa (0.049, P = 0.001), whereas there was no difference in crypt multiplicity. ACF were classified into three groups according to histological features: ACF with mild alterations (hypertrophic ACF, 73%), ACF with hyperplasia (hyperplastic ACF, 17%) and ACF with dysplasia (microadenomas, 10%). The proportions of ACF in the three groups were similar in the two provinces. Density of ACF was higher and crypt multiplicity lower proceeding from proximal to distal large bowel. Microadenomas were observed only in the colon, whereas hyperplastic ACF were more frequent in the rectum. In conclusion, density of ACF correlates with colorectal cancer rates in two Italian provinces, and shows a positive gradient from proximal to distal large bowel. Histology of ACF suggests that they may be precursors of both hyperplastic and adenomatous polyps. These data provide further evidence of the role of ACF in human colorectal carcinogenesis.

Aged↗
PubMed1997

Experimental ischemic liver injury and regeneration over 3 months: histological observations in the rat.

Liver histopathology of segmental portal ischemia occurring over a long-term period has not been previously described. For these reasons histological changes in the rat liver were studied from 1 h to up to 90 days after a left lateral and middle segmental portal obstruction. Within 3 h, the hepatocytes showed glycogen depletion in Rappaport zones 1 and 2 and pericentral and central lobular congestion of sinusoids and veins, whereas within 3 days, vein thrombosis appeared in the center of the lobule and liver necrosis was observed in Rappaport zones 2 or 3 or both, followed by restitutio ad integrum of the liver lobule morphology after 20-40 days. These results can be explained in light of two conditions occurring in the rat liver: (i) the peculiar low sensitivity of the liver to O2 debit and the protective or vasoactive effects used during hypoxia; and (ii) the sinusoidal network as a collateral source of the hepatic vascular system. Therefore, morphological assessment of this arteriolar and sinusoidal system, implicated in assuring efficient collateral blood supply in the rat liver with portal ischemia, is essential for understanding the mechanisms behind a natural and timely repair of ischemic injuries in the human liver.

Animals↗
PubMed1997

[Toxic megacolon. Apropos 3 cases].

The authors describe their experience with three cases of toxic megacolon: two cases were complications of an ulcerative colitis and died after surgery; one case was a complication of Crohn's disease and recovered after medical resuscitation treatment. Diagnosis was based on clinical features and direct abdominal X-ray showing an evident dilatation of the colon. The authors think that intense medical treatment has to be carried out in all cases without urgent surgical indication: even if not always successful, a medical therapy will be an appropriate preparation for operation. The authors believe that the operation of choice is colectomy with ileo-rectal anastomosis plus upstream protective ileostomy or right terminal ileostomy plus left iliac sigmoidostomy with subsequent reconstruction of continuity.

Aged↗
PubMed1997

[Preoperative radiotherapy in cancer of the rectum. Our 5-year experience].

Since 1990, 41 patients with rectal carcinoma have been submitted to preoperative radiotherapy, which induced a shrinkage of the tumor, favouring its surgical resection. Besides, in 3 cases the operative specimens were tumor free, and a higher incidence of A and B 1 categories was found. Surgical results have been compared with an analogous group of 20 patients, where surgery was performed as a first procedure, then followed by radiotherapy in 9. No increase of postoperative complications was observed. While analysis of follow-up results demonstrates a decrease of tumour recurrence in patients with preoperative radiotherapy, no difference in survival was registered, because of the development of extra-pelvic metastases.

Adult↗
PubMed1996

Experimental acute infectious pancreatitis in rats: histological observations.

Microbic contamination has been shown to be a secondary pathogenetic factor in different models of acute pancreatitis. In this paper, we developed an experimental bacterial model of necrotizing acute pancreatitis (NAP). Forty rats were treated by direct inoculation of a suspension of a clinically isolated strain of Escherichia coli, with three different single 0.33 ml injections, into the head, body and tail of the pancreas. Twenty five rats were sham operated and injected with saline. All animals were sacrificed at 48 hours, 4, 6, and 12 days. This experimental model appeared easy to execute without evidence of mortality. Histomorphologically, haemorrhagic NAP was observed, with its final recovery and minimal residual and focal fibrosis of the gland. As reported in the literature, our data underline the relevance of the bacterial component on pathogenesis of NAP, especially as an aggravating factor.

Acute Disease↗
PubMed1996

[Gallbladder carcinoma today: light and shadow].

On the basis of 30 clinical observations, the authors discuss the clinical and diagnostic features of carcinoma of the gallbladder, which is observed just in an advanced stage in the most part of cases. They also confirm its often poor prognosis. To-day echography and computed tomography play an important role in the preoperative diagnosis.

Aged↗
PubMed1995

Experimental acute hepatic vein occlusion: histological observations in the rat.

The histological consequences of hepatic venous outflow obstruction were studied in the rat. Circulatory changes as venous congestion and interstitial fluid accumulation are followed by signs of cellular damage progressing till hemorrhagic infiltration and focal necrosis. These are quite completely reversible in a period of 15 days.

Acute Disease↗
PubMed1992

[Imaging diagnosis, echography and CAT in mechanical jaundice].

In a review of 70 cases of extra-hepatic cholestasis of different origin, the great diagnostic value of imaging techniques, echography and computed tomography, was demonstrated in distinguishing the type of jaundice, and in defining the cause and site of obstruction.

Adult↗