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L Dubuisson

Publications and source records attributed to L Dubuisson.

At least 37 records · Page 2Linked to original sources
PubMed1985

The sinusoidal barrier in rats with portacaval anastomosis: a morphometric study.

Shunting of portal blood in the rat leads to liver atrophy and to an increase in arterial blood flow with microcirculatory disturbances. The aim of this study was to investigate the effects of these disturbances on the liver sinusoidal barrier (endothelial and perisinusoidal cells) using morphometric techniques. Rats with portacaval anastomosis (PCA) and sham operated pair-fed controls were studied 3 months after the shunt. Sinusoidal volume density in PCA increased but not significantly and the volume density (Vv) of total endothelial (EC) and perisinusoidal cells (PSC) increased by 104.54% compared to sham operated pair-fed rats. The increase of EC Vv was not associated with an increase in surface density (Sv) suggesting a fall in the number of small fenestrations and an increase in cell thickness. This interpretation supports the morphological observations. The increase of PSC Vv was mainly related to the increase in their subendothelial processes Vv and not to that of the cell body Vv. Lipids Vv and RER Sv expressed per sinusoidal cells remained unchanged suggesting that the balance between the 2 hypothetical functions of the PSC, namely fibrogenesis and storage of vitamin A, was maintained. In conclusion, changes of EC and PSC after PCA result mainly in thickening of the sinusoidal barrier. This increase may impair exchanges between the sinusoidal lumen and Disse space and contribute to functional abnormalities.

Animals↗
PubMed1985

Hyperplastic foci in the atrophic liver of rats after portacaval anastomosis.

Hyperplastic focal areas were investigated in livers of male rats 1 and 9 months after portacaval anastomosis (PCA) by light and electron microscopy. These alterations, predominantly found in periportal areas, were characterized by light microscopy as clusters of enlarged hepatocytes along narrowed sinusoids, contrasting in the remaining liver acinus with smaller hepatocytes along widened sinusoids. No differences were observed between 1 and 9 months PCA except for glycogen content, which was homogeneously distributed in the liver at 1 month but completely lacking in foci at 9 months. The most striking ultrastructural alterations were the sinusoids delimited in these hyperplastic areas by a thickened barrier consisting of thick endothelial cells encircled by numerous subendothelial processes of the perisinusoidal fat-storing cells. Deep and widened recesses of the sinusoidal lumen separated the two-cell-thick plates of the hyperplastic cells. Hepatocytes in foci, thought to represent regenerative areas, tend to increase their exchange surface. Their progressive loss in glycogen and their two-cell-thick plates architecture should be in favour of a potential malignancy. However, the spontaneous evolution of these foci which do not necessarily give rise to nodules, as well as the lack of other features of transformation, do not support this possibility.

Animals↗
PubMed1984

Neoplastic surface changes in urothelium of rats after portacaval anastomosis. A combined light and scanning electron microscopic study.

The development of preneoplastic and neoplastic alterations in the urinary tract was investigated by light and scanning electron microscopy in rats after portacaval anastomosis. The changes consisted of slight hyperplasia to papillary hyperplasia after 24 weeks. Carcinomas were present in all animals after 52 weeks. Surface characteristics can be correlated with the sequence of changes in urothelial cells. Short uniform microvilli appear in moderate hyperplasia and a cobblestone formation of the cells is typical of papillary hyperplasia. In transitional cell carcinomas the cells varied in shape and size and they were densely covered with pleomorphic microvilli. Although the cause of tumour induction after portacaval anastomosis is not clearly understood, possible mechanisms are discussed.

Animals↗
PubMed1984

Ultrastructural characteristics of hyperplastic alterations in the liver of congenital portacaval-shunt rats.

A congenital portacaval shunt was discovered in five rats. In these animals the hepatic artery was the only blood vessel perfusing the liver; the portal vein was absent. The livers were small and mainly hypoplastic, but light microscopy revealed the occurrence of focal hyperplastic alterations and occasional hyperplastic nodules. TEM and SEM showed these areas to be composed of clustered hepatocytes, separated by widened intercellular spaces. The cell membranes carried numerous pleomorphic microvilli, and the cytoplasma contained densely packed mitochondria, some of which were giant sized. Liver cells in the centrilobular region were hypoplastic. Comparison with findings of experimental portacaval anastomosis suggest that in congenital-shunt animals, the overall hypoplasia of the liver with the formation of hyperplastic areas is a consequence of the lack of portal blood.

Animals↗
PubMed1984

Hypertrophy of the rat Golgi complex during enhancement of cholesterol and bile acids synthesis.

There are some evidences that the Golgi apparatus could be involved in bile salts transport. In this study we investigate the morphology of the Golgi apparatus in rats with a chronic bile fistula or treated with 4% cholestyramine, a bile salts chelating agent. In both models liver histology was normal by light microscopy. With electron microscopy--compared to sham groups--the only obvious change was the enlargement of the Golgi complex. Morphometric data confirmed that the Golgi rich area volume density was almost doubled after chronic bile fistula or cholestyramine treatment. These data give another support for the participation of the Golgi complex in bile salts transport.

Animals↗
PubMed1984

Hepatocyte ultrastructure in the rat after long term portacaval anastomosis: a morphometric study.

Hepatocyte ultrastructure was studied in rats after long term portacaval anastomosis (PCS). Compared to controls rats of the same age, in one year PCS rats, the liver atrophy was 24% of the mass. Hepatocytes area was decreased (-16%) but their architecture was grossly normal. The rough endoplasmic reticulum appeared well developed. The morphometric study revealed that: the rough endoplasmic surface density was significantly increased in the two zones of the liver acinus, the smooth endoplasmic reticulum surface density was significantly decreased in zone 1 only and the peroxisomes volume density was increased 2.5 times. These findings differ from data obtained shortly after surgery and probably indicate an adaptation to important functions such as protein synthesis, drug metabolism etc. Increased number of peroxisomes could be possibly linked to the abnormal uric acid metabolism observed in rats with portacaval shunts.

Animals↗
PubMed1983

Failure to induce selective cholestasis in the rat after long-term extrahepatic selective biliary obstruction.

Forty-eight hours after extra-hepatic selective biliary obstruction (SBO), there is evidence of cholestasis in the obstructed lobes (OL). However, some major ultrastructural features of cholestasis are missing. The aim of this work was to investigate the long-term effect of SBO. One month after surgery, and in comparison with sham-operated rats, bile flow, liver weight, and liver weight ratio of obstructed/nonobstructed lobes were normal. Furthermore, there was no evidence of cholestasis in OL by light and electron microscopy. Bile duct communications between obstructed and non-obstructed lobes were evidenced by Indian ink injection. In sham-operated rats, bile duct communications between ducts of the different lobes were involved in bile drainage. It appears, therefore, that the main reason for the lack of cholestasis 1 month after SBO is the drainage of bile from OL through accessory bile ducts.

Animals↗
PubMed1982

Hepatocyte ultrastructure in rats with portacaval shunt. A morphometric study of acinar zones.

The principal reported morphological consequence of portacaval shunt in the rat is liver atrophy. The present study was designed to investigate ultrastructural changes in hepatocytes using electron microscopy morphometry. Two weeks following portacaval shunt, rat livers were fixed by perfusion and hepatocyte organelles from the two opposite zones of the acinus (zones 1 and 3) were quantified. Liver weight/body weight decreased by 50%, hepatocyte-specific volume decreased by 30% (28% in zone 1 nd 35% in zone 3). Estimated sinusoidal space increased, and estimated number of hepatocytes decreased by 50%. Hepatocytes had a normal ultrastructure except for mitochondria. Smooth endoplasmic reticulum-specific surface area was reduced by 65% (zone 3), and rough endoplasmic reticulum surface density was increased in zone 1 only. Mitochondria-specific volume was unchanged but decreased inner and outer membrane-specific surface area in zone 3 suggests in this zone a change in their conformation and possibly their number. Golgi-rich area surface density increased but not significantly. Hepatocyte loss and atrophy and rearrangement of organelles represent a new ultrastructural steady state following portacaval shunt that may help explain the new functional steady state.

Animals↗
PubMed1982

Sinusoidal cells in rats with portacaval shunt: a morphometric study.

Sinusoidal cells were studied in rats 2 weeks after portacaval shunt. Livers were perfused with glutaraldehyde via the aorta. Morphometric analysis was performed in periportal and centrolobular zones of the liver acinus. Liver atrophy was the main consequence of portal blood derivation. Per unit of hepatic parenchyma the number of hepatocytes and Kuppfer cells counted on 1 micron section was comparable in portacaval shunt and sham operated rats. 2 weeks after the shunt, sinusoidal cell ultrastructure was nearly normal. Morphometric analysis showed sinusoids slightly enlarged and Kupffer cell volume density increased in both zones. Kupffer cell lysosomal-like structures such as electron-lucent vacuoles and phagolysosomes had larger volume density. Ito cells number and volume density slightly increased after portacaval shunt. These findings suggest that endotoxemia which could occur after portal blood shunting might be better related to shunting than to depression of the reticuloendothelial system.

Animals↗
PubMed1981

Liver arterialization improves hepatocytes ultrastructure in rats with portacaval shunts.

The effect of arterialization (ART) of the distal stump of the portal vein after portacaval shunt (PCS) on bile formation and liver ultrastructure was assessed. ART using the left gastric artery was performed in male Wistar rats. Animals were sacrificed 3 weeks later. ART prevented body and liver atrophy. However, the liver weight to body weight ratio was significantly decreased when compared to sham PCS (2.5 +/- 0.36 vs 3.22 +/- 0.15). Reduction in total bile secretion (microliter/min) seen following PCS is reversed by ART. ART partly corrected hepatocyte size atrophy and the major ultrastructural abnormalities, namely the irregularity of the nucleus and dilation of the nuclear envelope and of the rough endoplasmic reticulum appearing after PCS. However, mitochondria remained swollen, deformed and enlarged with scission figures. No lesions in connection with ART were seen. This result confirms, at the ultrastructural level, the beneficial effect of ART in PCS.

Animals↗
PubMed1981

Chronic biliary drainage corrects liver atrophy induced by portacaval shunt in the rat.

Portacaval shunt induces a severe liver atrophy. The relative liver hypertrophy induced by chronic biliary drainage was studied by electron microscopy. Rats with either portacaval or sham portacaval shunt had a 4-day chronic bile fistula. Compared with rats not submitted to chronic bile fistula, liver weight/body weight ratio increased from 1.84 to +/- 0.12 to 3.54 +/- 0.48 (p less than 0.05) in portacaval shunt and from 3.52 +/- 0.15 to 3.64 +/- 0.40 (p less than 0.05) in sham portacaval shunt (controls). Chronic bile fistula stimulated bile acid synthesis in the two groups. Furthermore, the initial low bile flow observed in portacaval shunt (rats) reached control values after chronic bile fistula. Ultrastructural abnormalities observed in portacaval shunt: atrophy of the hepatocyte mainly related to the atrophy of the rough and smooth endoplasmic reticulum, irregularity of the nucleus, dilatation of the nuclear envelope and of the rough endoplasmic reticulum, and swelling of mitochondria, were greatly modified by chronic bile fistula. The hepatocyte size increased, mitochondria appeared smaller than normal, the nuclear envelope and the rough endoplasmic reticulum were not dilated, and the rough and smooth endoplasmic reticulum were expanded. Chronic bile fistula had no noticeable effect on the liver in sham portacaval shunt. Either stimulation of bile salts synthesis or removal of bile salts, which could be toxic for the atrophic liver, are possible explanations for the relative hypertrophy of the liver.

Animals↗
PubMed1980

Unscheduled DNA synthesis in psoriatic skin after ultraviolet irradiation and the effects of a combined treatment with 8-methoxypsoralen and longwave ultraviolet radiation: a clinical study.

Biopsies were taken from psoriatic patients undergoing photochemotherapy and then studied by autoradiography to investigate possible unscheduled DNA synthesis (UDS) following 8-MOP photodamage in epidermal cels. No sparse labelling was found in seventy samples taken from twenty-four different patients during PUVA therapy, indicating a lack of UDS. In contrast, UDS was observed in three patients irradiated with an all-spectrum UV lamp, as a test for DNA damage and excision repair activity. The incorporation of 3HTdR in these keratinocytes which were not undergoing S-phase was not affected by the dose of UV-A received during different stages of PUVA treatment. The results are discussed in terms of repair of the induced photodamage at the level of DNA, and in relation to a possible risk of this treatment when it is given over a long period of time.

Adolescent↗
PubMed1979

[Ultrastructural study of the different zones of the rat liver acinus after portacaval anastomosis].

Liver atrophy is a main feature in rats with a porto caval shunt. Histological studies revealed small size hepatocytes. Ultrastructural differences between periportal and centrolobular zones were noticed, in particular, the dilatation of the nuclear envelope and of the rough endoplasmic reticulum which appeared dilated, desorganized and sometimes without ribosomes, was more pronounced in the periportal zone. Hepatocytes of this zone might be more sensitive to the decrease of O2 and/or hepatotrophic factors.

Animals↗
PubMed1978

[Ultrastructure of testicular Sertoli cells in normal and dysgenesic rats, during the fetal and postnatal periods].

Electron microscopic study of Sertoli cells from normal and Misulban-treated rats has been realized during foetal and postnatal life. From 15th day of foetal life, morphological aspects of Sertoli cells plead for a steroidogen activity and protein synthesis. Ultrastructural organels of Sertoli cells are the same in sterile and normal seminiferous tubule, except the Sertoli junctions which are less numerous in sterile tubules and appear later.

Animals↗