Emergency nurse. Value for money reports. A & E departments: value for money?
Explore the source record for details and available documents.
Emergencies↗
Biomedical subjects
E Marsden
Publications and source records attributed to E Marsden.
Expression of transforming growth factor-beta 1 during chemical hepatocarcinogenesis in the rat.
Cellular distribution of both transcripts and protein of transforming growth factor (TGF)-beta 1 was studied in preneoplastic nodules (6 cases) and primary hepatic carcinomas (16 hepatocellular carcinomas and 2 mixed tumors of hepatocellular carcinoma and cholangiocellular carcinoma) produced by Solt-Farber's protocol in rats using in situ hybridization and immunohistochemistry. The TGF-beta 1 transcripts were primarily observed in nonparenchymal cells, some of which were desmin-positive perisinusoidal cells, surrounding or within the preneoplastic nodules or carcinomas. The distribution of latent TGF-beta 1 protein was similar to the transcripts. However, mature TGF-beta 1, which was identified with CC-antibody, was only detected in nonparenchymal cells and connective tissue associated with carcinomas, but was not observed in preneoplastic nodules or in normal liver with the exception of the periportal space. There was no difference in TGF-beta 1 expression associated with tumor types or the differentiation status of primary hepatic carcinomas. The present study demonstrates that nonparenchymal cells, particularly desmin-positive perisinusoidal cells, are the principal source of TGF-beta 1 production during hepatocarcinogenesis. Furthermore, the data suggest that the close interaction between nonparenchymal cells and carcinoma cells may be necessary for the activation of latent TGF-beta 1. It is hypothesized that regulatory effects of TGF-beta 1 on growth of preneoplastic or carcinoma cells in the liver are exerted via paracrine mechanism.
Animals↗
Cellular distribution of transforming growth factor-beta 1 and procollagen types I, III, and IV transcripts in carbon tetrachloride-induced rat liver fibrosis.
The cellular distribution and temporal expression of transcripts from transforming growth factor-beta 1 (TGF-beta 1) and procollagen alpha 1(I), alpha 1(III), and alpha 1(IV) genes were studied in carbon tetrachloride (CCl4)-induced rat liver fibrosis by using in situ hybridization technique. During the fibrotic process, TGF-beta 1 and procollagen genes were similarly and predominantly expressed in Desmin-positive perisinusoidal cells (e.g., fat-storing cells and myofibroblasts) and fibroblasts and their expression continued to be higher than those observed in control rats. These transcripts were also observed in inflammatory cells mainly granulocytes and macrophage-like cells at the early stages of liver fibrosis. The production of extracellular matrix along small blood vessels and fibrous septa coincided with the expression of these genes. Expression of TGF-beta 1 and procollagen genes were not detected in hepatocytes throughout the experiment. No significant differences in cellular distribution or time course of gene expression among procollagen alpha 1(I), alpha 1(III), and alpha 1(IV) were observed. Desmin-positive perisinusoidal cells and fibroblasts appeared to play the principal role in synthesis of collagens in CCl4-induced hepatic fibrosis. The simultaneous expression of TGF-beta 1 and procollagen genes in mesenchymal cells, including Desmin-positive perisinusoidal cells, during hepatic fibrosis suggests the possibility that TGF-beta 1 may have an important role in the production of fibrosis.
Albumins↗
In vivo differentiation of rat liver oval cells into hepatocytes.
The Solt-Farber protocol, in the absence of an initiating agent, was used to examine the precursor-product relationship between oval cells and hepatocytes in rat liver. The animals were administered 2-acetylaminofluorene (AAF) by gavage for 2 wk combined with partial hepatectomy 1 wk after administering AAF Two dose levels of AAF were used: 9- and 21-mg total dose for animals in Groups I and II, respectively. [3H]Thymidine was administered i.p. to one-half of the animals at Day 6 post-partial hepatectomy. Animals were sacrificed 7, 9, 11, and 13 days after surgery. Only oval cells became labeled on Day 7 in both groups. On Day 9 both labeled oval cells and labeled basophilic hepatocytes were present in Group I, whereas in Group II only oval cells remained labeled. On Days 11 and 13 both oval cells and basophilic hepatocytes were labeled in both groups. The total amount of radioactivity in Group II livers remained the same on Day 9 when only labeled oval cells were present and on Days 11 and 13 when both labeled oval cells and labeled basophilic hepatocytes were present. The calculated half-life for basophilic hepatocytes was about 50 h. The differentiation of oval cells into basophilic hepatocytes was delayed in Group II as compared to Group I, and the higher dose of AAF also induced the formation of both intestinal metaplasia and bile duct formation. In situ hybridization with an alpha-fetoprotein probe showed a strong expression in groups of typical oval cells and in cells arranged in duct-like structures. In addition a transient expression of AFP was also observed in the areas of basophilic hepatocytes 9 to 11 days after partial hepatectomy. Administration of AAF decreased the level of albumin mRNA in preexisting hepatocytes and caused a significant decrease of serum albumin. In contrast, oval cells showed a strong albumin expression, and basophilic hepatocytes formed islands of albumin-expressing cells. Oval cells and the foci of early basophilic hepatocytes lacked glucose-6-phosphatase activity. At Day 13 significant numbers of basophilic hepatocytes were positive for glucose-6-phosphatase. Oval cells were strongly gamma-glutamyltranspeptidase positive, whereas the foci of basophilic hepatocytes were negative for gamma-glutamyltranspeptidase. Only occasionally were transiently gamma-glutamyltranspeptidase-positive hepatocytes observed in basophilic foci. In summary our data indicate that oval cells can differentiate to hepatocytes and may have an important physiological function as a source of major serum proteins when hepatocytes are unable to synthesize these proteins.
2-Acetylaminofluorene↗
Cellular distribution of c-myc transcripts during chemical hepatocarcinogenesis in rats.
The expression of cellular myc (c-myc) was studied during early and late stages of chemical hepatocarcinogenesis in the rat using Northern blot analysis and in situ hybridization. Hepatocarcinogenesis was induced according to the resistant hepatocyte model of Solt and Farber. An uninitiated version of this model was also used to examine the expression of c-myc during proliferation and differentiation of oval cells. The expression of c-myc was increased throughout hepatocarcinogenesis starting with early preneoplastic foci and oval cells. Similar levels of c-myc transcripts were detected in oval cells and basophilic hepatocytes generated by the uninitiated version of the protocol as were found in preneoplastic foci and oval cells during hepatocarcinogenesis. Whereas c-myc expression remained elevated in late neoplastic nodules and carcinomas, it gradually declined in both "remodelling" nodules and uninitiated livers. Our data indicate that c-myc expression is elevated during the undifferentiated stages of hepatocyte development. Furthermore, the data support the hypothesis that a critical early step in chemical hepatocarcinogenesis involves a block in the normal differentiation program of the hepatocytes.
Animals↗
In situ hybridization studies on expression of albumin and alpha-fetoprotein during the early stage of neoplastic transformation in rat liver.
The expressions of albumin and alpha-fetoprotein (AFP) genes were studied in early preneoplastic liver lesions produced by the Solt-Farber protocol using "in situ" hybridization with single stranded RNA probes. In normal rat liver, albumin was expressed at a lower level in the centrilobular than in the periportal areas of the liver acinus, whereas the bile duct epithelium did not show any expression. Five weeks after initiation with diethylnitrosamine, islands of hepatocytes were present which showed heterogeneous expression of albumin and were surrounded by cells comprised of albumin negative hepatocytes and oval cells. gamma-Glutamyltranspeptidase positive foci of enzyme altered cells were located in albumin positive areas. Albumin expression gradually decreased in permanent nodules but increased in the hepatocytes outside the nodules during the first five months after initiation with diethylnitrosamine. Remodeling nodules, which were partly gamma-glutamyltranspeptidase and albumin positive, were also present. However, no consistent correlation was found between gamma-glutamyltranspeptidase positive and albumin negative areas during the first 5 months after initiation. Occasionally, cells showing an elevated expression of albumin were found in permanent nodules. These cells were located in the vicinity of oval type cells, which also showed a weak expression of albumin. AFP was expressed at high level in oval cells 5 weeks after the initiation. However, oval cells observed at later time points, either around the neoplastic nodules or inside the nodules showed only low expression of AFP. Hepatocytes in the enzyme-altered foci and in neoplastic nodules were always negative for AFP. The presence of strongly albumin positive cells inside the neoplastic nodules in close proximity to oval type cells suggests that these cells may be derived from primitive "stem-cell"-like oval cells.
Albumins↗
A precursor-product relationship exists between oval cells and hepatocytes in rat liver.
Oval cell proliferation was induced in twelve male Fischer rats by administration of 2-acetylaminofluorene (2-AAF) for 2 weeks and by performing partial hepatectomy one week after the beginning of 2-AAF administration. Albumin expression in liver was studied by using in situ hybridization of 3H-labeled rat albumin riboprobe. Radiolabeled thymidine was administered to a group of animals at day 6 after partial hepatectomy. The animals were killed at 0, 3, 7, 9, 11 and 13 days after partial hepatectomy. Both oval cells and basophilic hepatocytes showed a prominent expression of albumin, whereas albumin expression in acidophilic pre-existing hepatocytes was decreased. Oval cell nuclei were exclusively labeled one day after administration of [3H]thymidine. At day 9, 11 and 13 basophilic hepatocytes became labeled and the area occupied by these cells increased. This is the first demonstration of the transfer of radiolabeled thymidine from oval cells to newly formed hepatocytes in vivo. Thus the precursor-product relationship between oval cells and basophilic hepatocytes has been established.
2-Acetylaminofluorene↗
Histochemical changes in livers from portacaval-shunted rats.
Portacaval shunt (PCS) operations were performed on male inbred SD rats. The activity of liver gamma-glutamyltranspeptidase (GGT) increased a few days after the operation and remained high after several months. However, the activity was only present in periportal areas of liver lobules and was mainly restricted to the endothelial lining cells of periportal blood vessels. Phenobarbital sodium (CAS: 57-03-7) administration did not change the distribution of GGT. The activity of liver glucose-6-phosphatase disappeared in the centrilobular areas a few days after the operation but was present in the periportal areas. The distribution of this activity returned to normal after several months. The capacity of liver cells to store glycogen was significantly decreased following the PCS operation. Morphologic changes in hepatocytes observed after the PCS operation did not show similarities to those seen in preneoplastic livers. The nuclei of the small compact hepatocytes found in the animals with PCS were irregular in shape and stained intensively with hematoxylin and eosin. The large pale-staining cells in the periphery of liver lobes were GGT negative and their nuclei had a normal morphology. Neither morphologic nor histochemical changes consistent with preneoplastic and/or neoplastic stage were observed after 10 months in the liver when the PCS operation was performed on rats having received an ip dose (10 mg/kg) of diethylnitrosamine (CAS: 55-18-5) 2 weeks prior to the operation.
Animals↗
Measurement of cell proliferation in microculture using Hoechst 33342 for the rapid semiautomated microfluorimetric determination of chromatin DNA.
We report the development and characterization of a semiautomated method for measurement of cell proliferation in microculture using Hoechst 33342, a non-toxic specific vital stain for DNA. In this assay, fluorescence resulting from interaction of cell chromatin DNA with Hoechst 33342 dye was measured by an instrument that automatically reads the fluorescence of each well of a 96-well microtiter plate within 1 min. Each cell line examined was shown to require different Hoechst 33342 concentrations and time of incubation with the dye to attain optimum fluorescence in the assay. In all cell lines, cell chromatin-enhanced Hoechst 33342 fluorescence was shown to be a linear function of the number of cells or cell nuclei per well when optimum assay conditions were employed. Because of this linear relation, equivalent cell doubling times were calculated from growth curves based on changes in cell counts or changes in Hoechst/DNA fluorescence and the fluorimetric assay was shown to be useful for the direct assay of the influence of growth factors on cell proliferation. The fluorimetric assay also provided a means for normalizing the incorporation of tritiated thymidine ( [3H] TdR) into DNA; normalized values of DPM per fluorescence unit closely paralleled values of percent 3H-labelled nuclei when DNA synthesis was studied as a function of the concentration of rat serum in the medium. In summary, the chromatin-enhanced Hoechst 33342 fluorimetric assay provides a rapid, simple, and reproducible means for estimating cell proliferation by direct measurement of changes in cell fluorescence or by measurement of changes in the normalized incorporation of thymidine into DNA.
Animals↗
Regulation of heme metabolism and cytochrome P-450 levels in primary culture of rat hepatocytes in a defined medium.
Liver cells were prepared from adult Sprague-Dawley rats and used for the determination of delta-aminolevulinic acid synthetase (ALAS) activity and cytochrome P-450 concentrations at different time intervals in tissue culture in a serum-free synthetic medium. During the first 24 hr in culture, the level of cytochrome P-450 decreased to 30-40% of the level in isolated liver cells from untreated animals. The disappearance of cytochrome P-450 was especially fast in hepatocytes obtained from female phenobarbital-treated rats where only 40% of the original cytochrome P-450 was present after 2 hr in culture and 80% had disappeared in 2 days. The activity of ALAS increased 3- to 4-fold when measured 2 hr after plating, and it reached the maximum level in 19-24 hr when its activity was about eight times the original activity. In 2-4 days in culture, the activity of ALAS was four to five times above the original level. When the amount of delta-aminolevulinic acid (ALA) in the medium was increased from 1 to 100 microM, a decrease in ALAS was obtained, but no significant increase in cytochrome P-450 level was observed. Addition of heme to the medium gave a dose-dependent decrease in the activity of ALAS. Our data indicate that during the first 24 hr in culture the increase of ALAS activity was prevented by exogenous heme. This effect may be due to inhibition of the catalytic activity, suppression of the synthesis of the enzyme, or accelerated breakdown of the enzyme by heme.
5-Aminolevulinate Synthetase↗
Isolation of preneoplastic rat liver cells by centrifugal elutriation and binding to asialofetuin.
Putative preneoplastic hepatocytes were isolated from male Fischer 344 rats treated with a single dose of diethylnitrosamine, 2-acetylaminofluorene feeding, and partial hepatectomy (Solt-Farber model). The isolation procedure involved, after collagenase dispersion of the liver, separation of the hepatocytes into small- and large-cell fractions by centrifugal elutriation, and subsequent selection of cells deficient in asialoglycoprotein receptor(s) by plating onto asialofetuin (ASF)-coated plates. The number of cell surface binding sites for the asialoglycoprotein receptor was measured with both asialoorosomucoid and ASF as ligands. There was a 50% reduction of binding sites for both ligands in the original cell suspensions obtained from preneoplastic livers. The reduction in receptor binding sites was most pronounced in the large cell fraction (less than or equal to 30% of control value) after separating the original cell suspension by elutriation into small and large cell fractions. Immunohistochemical studies showed a lack of asialoglycoprotein receptor in preneoplastic (i.e., hyperplastic foci) areas. These areas were entirely super-imposable with glucose-6-phosphatase-deficient areas and partially overlapped the gamma-glutamyltranspeptidase-positive areas in serial liver sections. The attachment of preneoplastic hepatocytes to ASF-coated tissue culture dishes was greatly impaired, and the number of gamma-glutamyltranspeptidase-positive cells on the ASF dishes was reduced to less than 7% as compared to 45 to 70% on the collagen-coated plates. Thus, the lack of asialoglycoprotein (asialofetuin) surface receptors and the increased size of the early preneoplastic hepatocytes are characteristics that can be used to separate the preneoplastic cell population from normal liver cells.
2-Acetylaminofluorene↗
Mutagenicity and DNA damage induced by arylamines in the Salmonella/hepatocyte system.
Coincubation of isolated, intact rat hepatocytes with Salmonella typhimurium tester strain TA 98 (Salmonella/hepatocyte system) has been employed to determine both bacterial mutagenicity and DNA damage in rat hepatocytes following treatment with 2-acetylaminofluorene (AAF) and its derivatives. In vivo pretreatment of rats with either 2,3,7,8-tetrachlorodibenzodioxin or 3-methylcholanthrene markedly increased both DNA damage and bacterial mutation frequency upon incubation of AAF or 2-aminofluorene (AF) in this system. The increase in damage to the hepatocyte DNA was more pronounced after AAF treatment than following AF exposure, while the increase in bacterial mutation frequency was greater after AF treatment. Treatment of hepatocytes with paraoxon prior to exposure to N-hydroxy-2-acetylaminofluorene (N-OH-AAF) or N-acetoxy-2-acetylaminofluorene (N-OAc-AAF) partially inhibited both DNA damage and the bacterial mutagenicity caused by these agents. Treatment of primary rat hepatocytes with 2-hydroxy-2-aminofluorene (N-OH-AF) causes a low level of DNA breaks. Substitution of primary rat hepatocytes with highly differentiated rat hepatoma cells (Reuber H4-II-E) revealed a low level of DNA breakage after exposure to N-OH-AAF whereas treatment with either N-OAc-AAF or N-OH-AF induced a dose dependent increase in DNA breaks. Pretreatment of the Reuber cells with paraoxon inhibited the DNA damage caused by N-OAc-AAF whereas the DNA damage induced by N-OH-AF was increased after paraoxon treatment. Employing host cells with differing metabolic capacity, such as Reuber vs. primary hepatocytes, in the Salmonella/hepatocyte system, may allow a determination of the relative importance of different metabolic pathways in mutagenicity and/or genotoxicity of arylamines.
2-Acetylaminofluorene↗
Some aspects of the relationship of radioactivity to lung cancer.
Explore the source record for details and available documents.
Air Pollution, Radioactive↗
Outpatient nurses must adapt to survive.
Outpatient nursing has long been considered a clinical backwater. However, recent critical reports, the NHS reforms and other trends in healthcare are likely to change this. Outpatient nurses must move quickly to develop a new role for themselves or the opportunity will be lost. They should aim to make the best possible use of their nursing skills, given that outpatients need nursing care.
Ambulatory Care↗
Skill mix: stretching shrinking nurses.
Explore the source record for details and available documents.
Humans↗
Nursing examinations.
Explore the source record for details and available documents.
Education, Nursing↗