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Biomedical subjects

C Rouleau

Publications and source records attributed to C Rouleau.

14 recordsLinked to original sources
PubMed2002

Histopathological evidence of inorganic mercury and methyl mercury toxicity in the arctic charr (Salvelinus alpinus).

In our sustained effort to understand mechanisms of mercury toxicity in fish, the histopathological effects of a 96-h acute exposure to water-borne inorganic mercury (inorganic Hg) (15 micro gL(-1)), as well as those of a single dietary dose of inorganic and methyl mercury (methyl Hg) (0.260.05 micro g.Hgg(-1) body weight), over 30 days were examined. Samples of gills, olfactory epithelium, kidneys, and liver of arctic charr, Salvelinus alpinus, were studied using light and electron microscopy. The distribution of dietary inorganic and methyl Hg in the intestinal epithelium was determined using 203Hg microautoradiography. Gills of fish exposed to water-borne inorganic Hg presented a severe disorganization of epithelial cells after 12h and modifications of cilia of ciliated olfactory cells appeared after 24h. Nevertheless, a partial recovery was seen in both tissues by the end of the 96-h exposure period. Liver was little affected by water-borne and single-trophic-dose contamination of inorganic Hg, but dietary methyl Hg had drastic effects, despite its low dosage, with severe necrosis and alterations of cytoplasmic organization. Microautoradiograms showed that inorganic Hg was distributed evenly in the intestinal epithelium, whereas methyl Hg was found at very specific locations on the epithelial surface.

Animals↗
PubMed2001

Fine-scale tissue distribution of cadmium, inorganic mercury, and methylmercury in nymphs of the burrowing mayfly Hexagenia rigida studied by whole-body autoradiography.

The distribution of inorganic 109Cd(II), inorganic 203Hg(II), and [203Hg] methylmercury (MeHg) in nymphs of the burrowing mayfly Hexagenia rigida after exposure via water and sediments was studied. To better understand the mechanisms underlying the fate of Cd, Hg, and MeHg in this animal and to identify target organs, autoradiography of whole-body cryosections was used to obtain a detailed view of the distribution of the radiolabels. The gut and exoskeleton were the only structures labeled in nymphs exposed to Cd via water or sediments. After exposure to inorganic Hg via water, the Malpighian tubules exhibited a very high labeling, indicating that these organs may be a target for Hg toxicity. The distribution of Hg after exposure via sediments was similar, though the labeling of Malpighian tubules was less intense. Distribution of MeHg strongly differed between treatment groups. Nymphs were rather uniformly labeled after exposure via water, whereas in those exposed to MeHg in sediments, the intense labeling of all internal tissues contrasted with the very low labeling of the hemolymph, indicating that the translocation rate of the absorbed MeHg was faster in the latter group. This may be related to the complexation of MeHg by small thiol ligands in the gut as a result of the digestion process.

Animals↗
PubMed2000

Comparative uptake, bioaccumulation, and gill damages of inorganic mercury in tropical and nordic freshwater fish.

This paper reports comparative results on the bioaccumulation of inorganic mercury and resulting gill damages in the tropical fish, Trichomycterus zonatus, and a nordic species, Salvelinus alpinus, using radioisotope 203Hg techniques and scanning electron microscopy. Uptake of inorganic Hg from water was much more important in T. zonatus than in S. alpinus and the Hg concentration in S. alpinus increased at a slower rate in all tissues during the first 24 h of exposure. After 96 h, Hg concentration was 70 times higher in the kidney, 10 times higher in liver, intestine, skin, and brain, and 3 times higher in gills, muscle, and the rest of body of T. zonatus compared to S. alpinus. Gill damages in T. zonatus were more evident and occurred much earlier than for S. alpinus. According to our data, the high differences observed in the inorganic mercury uptake, bioaccumulation, and gills damages strongly suggest that T. zonatus is more sensitive to inorganic mercury pollution than S. alpinus. Further studies are urgently needed to determine whether the high sensitivity observed for T. zonatus to inorganic Hg is also present in the majority of tropical species or whether this species presents an isolated case.

Animals↗
PubMed1997

Variation of bcl-2 expression in breast ducts and lobules in relation to plasma progesterone levels: overexpression and absence of variation in fibroadenomas.

Some women with benign breast disease eventually develop breast cancer. The mammary gland undergoes tissue remodelling according to hormonal influences, involving a balance between quiescence, proliferation, and mechanisms of cell death. Proliferation and/or apoptotic events could therefore be investigated to help understand the mechanisms of benign lesion formation and identify mastopathies with a poor prognosis. bcl-2 expression was analysed by immunohistochemistry in 75 benign mastopathies. Protein levels were quantitated with an image analyser in various epithelial structures on frozen sections, including adenoses, fibroadenomas, ductal epithelial hyperplasias, cysts, and apparently normal surrounding lobules and ducts. bcl-2 levels were equivalent in apparently normal lobules and ducts, as well as in cysts and ductal hyperplasias. bcl-2 staining was significantly higher in fibroadenomas, known to be of lobular origin [mean = 10.1, quantitative immunochemistry score (QIC) arbitrary units (AU), n = 19], than in normal lobules (mean = 5.1 AU, n = 43, P = 7 x 10(-5). bcl-2 levels in normal lobules and ducts varied according to the menstrual cycle, being higher during the follicular than the luteal phase (P = 1.8 x 10(-2) and P = 1.7 x 10(-2), respectively). This was further supported by a statistical link (P = 5 x 10(-3) between high levels of circulating progesterone and weak bcl-2 staining in lobules and ducts. This progesterone-dependent variation was absent in fibroadenomas. No statistical correlation was found between bcl-2 expression and circulating levels of oestradiol, and follicle-stimulating or luteotrophic hormones. Although these are only preliminary results, they suggest an influence of progesterone on bcl-2 expression which might be lost in fibroadenomas. A hypothesis is proposed concerning the potential involvement of altered regulation of the apoptotic process in the formation of such benign lesions.

Breast Neoplasms↗
PubMed1993

Laparoscopy-assisted aortobifemoral bypass.

Therapeutic laparoscopy has substantially simplified the postoperative course of patients suffering from hepatobiliary, gastric, or colonic disease. One important advantage of this modality is the decrease in postoperative pain, which diminishes the potential for cardiopulmonary problems. Patients with aortoiliac atherosclerotic disease are at high risk for postoperative complications, and a minimally invasive procedure may favorably affect their postoperative recovery. We describe here the first patient on whom we performed a laparoscopy-assisted aortobifemoral bypass. Under the pneumoperitoneum, seven 10-mm trocars were inserted to permit aortic dissection and creation of retroperitoneal tunnels to the femoral regions. After evacuation of the pneumoperitoneum, an 8-cm midline incision was made to allow a side-to-end aortic anastomosis. The patient's postoperative period was uncomplicated by any cardiopulmonary problems despite his history of three myocardial infarctions; the patient had minimal pain that allowed for a quick return to ambulation. This procedure is minimally invasive and appeared to simplify the postoperative period in our patient. It could become the procedure of choice for certain patients with aortoiliac disease.

Anastomosis, Surgical↗
PubMed1988

Expanded PTFE prostheses as arterial substitutes in humans: late pathological findings in 73 excised grafts.

Through collaboration of surgeons, pathologists and bioengineers at five centers in Canada and France, this study analyzed the late pathology and structural changes in 73 expanded PTFE arterial prostheses harvested from patients at autopsies and reoperations. The degree of tissue encapsulation increased with the duration of implantation but was reduced by the presence of infection. In several cases, the fibrous tissue penetrated the wall of the prosthesis and partitioned off the thin outer layer, thus disrupting the delicate microporous structure of the wall. The presence of aneurysms was observed in models that had no external reinforcing layer and among grafts that apparently suffered from surgical trauma. Wrinkling of grafts was noted at areas of flexion and was often associated with thickening of the external capsule and reduced luminal diameters. Endothelialization was found within only a few millimeters of the anastomoses. The luminal surfaces were generally not well healed. The PTFE structure was usually readily visible under a thin covering of loosely adhering thrombotic deposits. Bacteria were observed in 46% of the cases, even though only 29% were considered clinically infected. The incidence of lipid or cholesterol deposits was high. Avoiding iatrogenic trauma to the external wall of the prosthesis during implantation is important. Those features where design improvements are required to provide longer term structural integrity and dimensional stability in future models of expanded PTFE prostheses should be identified.

Adult↗
PubMed1980

[Polyethylene terephtalate (Dacron) prostheses as arterial substitutes. Value of commercial grafts as abdominal aorta substitutes in the dog (author's transl)].

Most of the presently available Dacron fabric grafts are either woven or knitted; some are velours. Whereas the various configurations and textures can be easily recognized and classified with respect to morphology, structure, porosity and fabric tenacity, it is also necessary to establish their post-implantation healing characteristics. Canine models have been used to investigate the healing characteristics of 18 types of prostheses over implantation periods from one to six months using techniques of scanning electron microscopy and conventional light microscopy. Velours exhibit superiar tissue ingrowth but the internal tissue lining does seldom embeds all of the fibres. Complete neoendothelialization is not achieved; the process appears more closely linked to haemodynamic factors such as shear forces acting postfacto on blood deposits as opposed to graft porosity facilitating ingrowth. More meaningful criteria of performance must be found to allow a closer matching between the available products and the individual clinical needs of each situation.

Animals↗
PubMed1977

Dacron as arterial prosthetic material: nature, properties, brands, fate and perspectives.

Dacron graft prostheses are routinely implanted to overcome impairment of arterial flow to distal tissues. Many different fabric configurations have been developped and evaluated. Unfortunately, after implantation the flow surface of any graft persists as a fibrinous lining. No human specimen has a commonly ingrown extension of tissue exceeding some millimeters in length. Full wall healing and endothelialization of arterial prosthesis is a goal that must be pursued intensively because it seems that the goal is attainable.

Animals↗
PubMed1975

Preclotting and thrombosis of a dacron prosthesis. A scanning electron microscope study.

The authors report eht study of preclotting made on a knitted Dacron prostheses before implantation into a patient. Within 24 h of implantation, clotting occurred. The patient had to be reoperated, and a second preclotting followed. Specimens were removed at different times and fixed in a Rembaum solution before being dried and studied by scanning electron microscopy.

Aged↗
PubMed1975

Preclotting of knitted Dacron prosthesis. A scanning electron microscope study.

A scanning electron microscope study of preclotting on knitted Dacron prosthesis is reported. Five steps of the interaction are well identified: (1) before any blood contact (virgin Dacron), (2) during the first 3 minutes (fibrin and platelet aggregates), (3) fifth minute of contact (clotting), (4) 15 minutes of contact with heparinized blood (thin fibrin network), and (5) the following minutes (invasion of fibrin, which enmeshes blood cells).

Adult↗
PubMedDate not supplied

Effects of some chelating agents on the uptake and distribution of 54Mn(II) in the brown trout (Salmo trutta).

The effects of humic acids, which are natural metal-complexing compounds, and potassium ethylxanthate, sodium diethyldithiophosphate, sodium dimethyldithiocarbamate, and sodium diethyldithiocarbamate, which are sulphur-containing man-made chelating agents, on the uptake and tissue distribution of 54Mn(II) were studied in brown trout (Salmo trutta). Fish were exposed for 7 days to 0.1 microgram Mn(II).l-1 as MnCl2 (1 microCi 54MN.l-1) with or without chelating agents. Examination of the partition of Mn between octanol and a Tris-HCl buffer in the presence of these compounds was also performed. Humic acids had only small effects on Mn uptake and distribution in trout, probably because of the low stability of Mn-humate complexes. Partition of Mn in the presence of potassium ethylxanthate, sodium diethyldithiophosphate, sodium dimethyldithiocarbamate, and sodium diethyldithiocarbamate between octanol and Tris-HCl buffer showed formation of lipophilic complex with the latter two compounds, but not with the former. However, these four chelating agents all decreased Mn uptake in the trout by 40-45%. These substances also changed the distribution of Mn within the fish, with a higher proportion of the metal being present in some visceral organs and a smaller proportion being localized in some non-parenchymateous tissues, such as skins, fins and bones. The mechanisms underlying these effects are not known. However, the interaction of chelating agents with the Mn, although weak, may have partially withdrawn the metal from the uptake process in the gills. The redistribution of Mn in the fish may be due to the binding of the metal to complexing compounds which have reached the intestinal lumen.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗