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Biomedical subjects

G J Smith

Publications and source records attributed to G J Smith.

At least 109 records · Page 6Linked to original sources
PubMed1991

Proliferation of carcinogen-damaged hepatocytes during cell-cycle-dependent initiation of hepatocarcinogenesis in the rat.

Hepatocyte proliferation and damage to DNA were characterized during the initiation phase of carcinogenesis in livers of rats that had received a single administration of the methylating agent methyl(acetoxymethyl)nitrosamine (DMN-OAc). Quiescent non-proliferating hepatocytes in intact livers did not appear to be susceptible to initiation by DMN-OAc, whereas proliferating hepatocytes in the S phase appeared to have greatest risk. To characterize the phenomenology of S-phase-dependent initiation further, the fractions of hepatocytes in the S and M phases of the cell cycle were enumerated at various times after treatment with DMN-OAc. Hepatocytes treated when in G1 experienced a delay of up to 20 h in the onset of S phase and a reduced rate of entry into the S and M cycle phases. Hepatocytes treated when in S phase experienced considerable delay in progression to mitosis due to part to inhibition of DNA replication. Hepatocytes treated when in late S/G2 also demonstrated a delay in progression into mitosis. The levels of 7-methylguanine and O6-methyldeoxyguanosine were quantified in the nuclear DNA of proliferating hepatocytes. The kinetics of removal of these lesions appeared to be first-order (half-life = 24 h). Hepatocyte risk of initiation was modeled by a function which summed over time the product of the fraction of hepatocytes in the S phase and the fraction of residual, unrepaired damage to DNA. For hepatocytes treated when in early G1, the time-weighted frequency of premutagenic DNA damage that was present during DNA replication was estimated to be less than half of that for hepatocytes treated when in early S. The results suggest that cell-cycle-dependent variation in sensitivity to initiation of hepatocarcinogenesis may be, in part, due to efficient removal of potentially carcinogenic lesions from DNA during an extended G1. The apparent high sensitivity of hepatocytes in late S/G2 suggests the contribution of additional factors.

Animals↗
PubMed1991

Differences in adhesion to tissue culture plastic of clonally related transformed and control sublines from an epithelial cell strain.

Clonally related sublines of the NAL1A lung epithelial cell strain were used in a comparison of the mechanism of attachment and the morphology of control and transformed epithelial cells. The initial attachment and spreading of the control cells on tissue culture plastic was shown to be dependent upon adsorption of serum vitronectin to the substratum. The alpha v subunit of the vitronectin receptor was detected in both the control and transformed cells by immunoprecipitation and immunoblot methods. The spontaneously transformed cells differed from the control cells in that, whereas attachment to tissue culture plastic could occur by binding to adsorbed vitronectin, the transformed cells could also become attached, with time, by a vitronectin-independent mechanism. Attachment by this vitronectin-independent reaction was inhibited by the protein synthesis inhibitor cycloheximide and also by the microtubule-disrupting drugs demicolcemid and nocodazole. The morphologies of attached control and transformed cells cultured on tissue culture plastic were disrupted by treatment with cytochalasin B, demicolcemid or nocodazole, indicating that the shape of these cultured epithelial cells is dependent upon the microtubule system as well as the actin filaments. These results show one important difference between the control and transformed cells, in that the transformed cells can attach to tissue culture plastic by a vitronectin-independent mechanism that involves new protein synthesis by the cell. Another interesting difference is that this vitronectin-independent attachment of the transformed cells was sensitive to inhibition by microtubule-disrupting agents. On the other hand, the attachment of either transformed or control cells to fibronectin- or vitronectin-coated surfaces was not affected by microtubule-disrupting agents.

Cell Adhesion↗
PubMed1991

Confocal laser scanning immunofluorescence microscopy of lamellar bodies and pulmonary surfactant protein A in isolated alveolar type II cells.

We have determined the distribution of surfactant protein A (SP-A) in isolated type II cells from the lungs of rats by using immunofluorescence in conjunction with a laser scanning microscope fitted with a confocal aperture. Because of the very narrow depth of field of this microscope (less than 0.4 microns) in the confocal format, we were able to optically section type II cells and determine both the distribution of SP-A in the type II cell and the distribution of the lamellar bodies. The location of SP-A was determined by using fluorescein isothiocyanate-labeled secondary antibodies and the lamellar body distribution by using the lipid soluble fluorescent stain Phosphine 3R. SP-A was detected in the cytoplasm of type II cells as asymmetrically distributed punctate fluorescent bodies that resembled lamellar bodies in terms of size, number, and distribution within the cytoplasm of the cell. Most of the SP-A was located within bodies of the type II cell. Diffuse patches of fluorescence were seen in other cytoplasmic regions as well as the number of the cell. We conclude that SP-A is localized primarily, but not exclusively, in lamellar bodies of type II cells and that laser scanning microscopy is a much superior technique for the localization of SP-A than conventional microscopy in terms of both sensitivity and resolution.

Animals↗
PubMed1990

Enhanced invasiveness and metastatic potential of epithelial cell lines cultured in the presence of dimethyl sulphoxide.

Several passage cycles of poorly metastatic malignant epithelial cells through immunosuppressed mice failed to induce enhanced metastasis-forming ability of cells derived from either the primary subcutaneous tumours or the resultant lung metastases. In vitro treatment of cultured malignant cells with dimethyl sulphoxide (DMSO) induced a reversible change in phenotype towards increased invasiveness but did not significantly increase metastasis formation. A cloned-cell line from a spontaneous in vitro transformant in the presence of DMSO was highly invasive and highly metastatic. In vitro treatment of cultured cells with 2% (v/v) DMSO produced alterations in morphology with decreased growth rate of all cell lines and decreased anchorage-independent colony formation in several malignant cell lines. All in vitro and in vivo effects were reversible following both short- and long-term (1 year) culture of cells in the presence of DMSO, suggesting epigenetic effects. These data support the concept of independent genetic controls for the invasiveness of tumours and the ability to form metastases.

Animals↗
PubMed1990

Adhesion to laminin and expression of laminin in clonally related transformed and control sublines from an alveolar epithelial cell strain.

Clonally related sublines of the NAL1A cell strain were used to examine the expression of laminin and the importance for the attachment and morphology of these control and spontaneously transformed alveolar epithelial cells. A laminin component was detected by immunoblot analysis in extracts of control cells cultured on plastic as a Mr 410,000 species consisting of disulfide-linked Mr 200,000 components. The laminin content of the malignant cells was reduced at least 40-fold as compared to that of the control cells. Cell attachment to laminin or to a laminin-like neurite promotion factor was compared with attachment to fibronectin and to extracellular matrix from bovine endothelial cells. Both control and transformed cells attached as well to laminin or neurite promotion factor as to fibronectin, in a serum-free adhesion assay. The control cells showed enhanced cell spreading on the surfaces coated with laminin, neurite promotion factor, or fibronectin. The transformed cells had very similar cell shape, as determined by phase contrast and scanning electron microscopy, when cultured on laminin or neurite promotion factor or fibronectin, as on tissue culture plastic.

Animals↗
PubMed1990

A solar erythemal radiation monitoring programme in New Zealand and Queensland, Australia.

Solar erythemal radiation dose measurements carried out at five locations in Australasia from 43 degrees S to 19 degrees S during the southern summer of 1984-85 are reported. Monthly erythemal doses at the New Zealand sites reached a maximum of 8 x 10(4) joules/m2 for January and February 1985. During February 1985 this dose was the same as that measured at Townsville, Queensland, and slightly greater than the 7.3 x 10(4) joules/m2 at Rockhampton, Queensland. These results highlight the difficulty of calculating levels of solar erythemal radiation based on the latitude of the site because of local variations in cloud cover patterns.

Atmosphere↗
PubMed1990

Cytogenetic profile of in vitro spontaneously transformed and chemical tumor-derived cell lines related to the mouse lung alveologenic carcinoma.

The karyotypes for a unique series of cloned untransformed and spontaneously and urethan-transformed mouse lung alveologenic carcinoma cell lines were compared by G-banding. All cell lines exhibited altered chromosome number accompanied by chromosomal aberrations. Both spontaneously and chemically transformed lines contained a higher proportion of cells carrying double minutes, short-arm chromosomes with no distinct banding pattern, and Robertsonian translocations between a variety of chromosomes. No common karyotypic abnormalities were observed among any of the transformed lines. These data suggest that enhanced genomic instability may lead to a critical subchromosomal molecular event(s) in generation of both spontaneously and chemically derived mouse lung alveologenic carcinoma.

Adenocarcinoma, Bronchiolo-Alveolar↗
PubMed1990

Activated Ki-ras proto-oncogene in spontaneously transformed and chemical tumor-derived cell lines related to the mouse lung alveologenic carcinoma.

An in vitro cell model of mouse lung alveologenic carcinoma consisting of preneoplastic nonmalignant cells, spontaneously transformed cells, and urethane-induced malignant cells was analyzed for phenotypic and genotypic changes associated with the transition to neoplasia. The polymerase chain reaction (PCR) was used to amplify the cDNA derived from the c-Ki-ras mRNA corresponding to exons 1 and 2 of the proto-oncogene. This approach allowed analysis of the gene transcription product rather than potentially unexpressed DNA. Direct sequencing of the PCR product identified a common single point mutation, alone or together with wild-type mRNA for c-Ki-ras, in all of the malignant clones. An A----G transition in the second base position of codon 61 was common to spontaneously malignant and chemical tumor-derived cell lines and to lines selected for lung metastatic behavior. The absence of the mutation in the nonmalignant cells suggests that the Ki-ras mutation may be a factor in onset or maintenance of the malignant phenotype and, at least in vitro, may be a late event in the transformation process.

Adenocarcinoma, Bronchiolo-Alveolar↗
PubMed1990

Histopathology and cell culture characteristics of liver cells from grc- and grc+ rats given diethylnitrosamine.

The histopathological response and cell culture characteristics of liver cells from the R16 (grc-) strain of rats, which carries an MHC-linked deletion, were examined one week after a single intraperitoneal injection of 200 mg/kg body weight diethylnitrosamine (DEN) and were compared with the response of liver cells from wild type (grc+) rats. The DEN exposure induced hydropic/vacuolar changes in the parenchymal cells and a limited proliferation of oval cells in the periportal areas of the livers of both grc+ and grc- rats. Primary culture of collagenase-digested livers consisted of parenchymal, bile ductular and oval-related cells as determined by cell-specific immunohistochemistry. Subpassaged cells from grc+ rats exhibited oval cell ultrastructural morphology, inducible histochemical staining for gamma-glutamyl transpeptidase (GGT), and DEN-associated onset of anchorage-independent growth. Primary cultures of liver cells from R16 rats consistently failed to form cell strains upon subpassage.

Analysis of Variance↗
PubMed1990

Outpatient percutaneous central venous access in cancer patients.

A 1-year experience of percutaneous subclavian catheterization in outpatients with cancer was reviewed to document reliability, safety, and cost. There were 763 catheter insertions attempted with prospective documentation of complications in 664 consecutive patients. Catheter insertion was successful in 722 attempts (95%). There were only 13 pneumothoraces (2%). Thirty catheters required repositioning (4%). The average catheter duration was 191 days (range: 0 to 892 days). Fifty-six catheters (8%) were removed because of suspected infection. Documented catheter sepsis occurred in 21 patients (3%); catheter site infection occurred in 8 patients (1%). Thus, only 0.22 infections per catheter year occurred during this 382 catheter-year experience. The estimated cost of catheter insertion was $562, which is one-third the estimated cost for tunneled catheters ($1,403) and for reservoir devices ($1,738). In our experience, percutaneous subclavian catheterization is a reliable, cost-effective method compared with tunneled or reservoir devices, with an equivalent incidence of catheter-related infections. The cornerstone of our success with this program is a staff dedicated to catheter care and intensive patient education. In centers where a large number of patients require central venous access, percutaneous catheterization should be the technique of choice.

Ambulatory Care↗
PubMed1990

Isolation and EBV-transformation of a minor population of normal human tonsillar B cells bearing a cold agglutinin-associated idiotope.

Human autoantibodies which bind to red blood cells and cause agglutination in the cold, collectively comprise the cold agglutinins: a subset of these antibodies with specificity for the Ii carbohydrate antigen on the red cell surface bears cross-reacting idiotypic determinants. A monoclonal antibody has been raised which specifically inhibits the cold agglutination reaction, and has been used to probe normal lymphoid cell populations for the presence of B cells expressing the same idiotope. Although such cells comprise only 1-2% of the lymphoid cells in the tonsil, it has been possible to isolate them in good yield and purity using the antibody and magnetic beads. Released cells were infected with the Epstein-Barr (EB) virus and an idiotope-bearing line established. The IgM secreted by the line was found to agglutinate red cells in the cold indicating that cold agglutinin-producing cells were among this idiotope-positive population. The immunophenotype of the line, and the agglutinating power of the secreted IgM, have been compared with a similarly immortalized idiotope-bearing line established from neoplastic B cells of a patient with frank cold agglutination disease.

Agglutinins↗
PubMed1990

The histopathology of pulmonary reactions to drugs.

Many pathologists and pulmonologists have trained and practiced in an era during which therapeutic options for patients have increased manyfold with regard to pharmacologic agents. Toxicity to the lung may be recognized as data accumulate in the form of case reports and clinical reviews to document the clinical and pathologic manifestations. For the histopathologist, paradoxically the more we learn the more difficult problems of interpretation become. Drug reactions previously described extensively at the autopsy now can be relatively easily interpreted in living patients with tissue obtained by open lung biopsy. This latter procedure is becoming less common with diffuse infiltrative lung disease in favor of the transbronchial biopsy in which sampling error abounds. There may be no disease or minimal change. The pathologic lesions may be duly noted and described, but then defy interpretation. An accurate differential diagnosis following biopsy may not solve the clinical problems for which a tissue diagnosis was sought. A specific diagnosis may be made that does not fit the clinical picture, or the real "answer" may be revealed distressingly later in the clinical-course or, more distressingly, at autopsy. The prudent histopathologist deals with such limitation by objectively stating the observable facets of tissue injury and synthesizing an interpretation. Notwithstanding the burgeoning literature on mechanisms of injury of toxic substances, the "state of the art" in 1990 for interpretation of pulmonary drug reactions still lies with the exacting judgment of experienced clinical physicians. Proper evaluation can result in exclusion of important mimickers of interstitial lung disease, usually infection and neoplasia; accurate categorization of tissue injury and comparison with known injurious responses to the drug in question may lead to a relatively specific diagnosis of drug-induced injury. Most drug reactions in the lung are classified as an interstitial pneumonia. This article illustrates and describes several interstitial reactions to injury that have few histologic features in common. However, because the lung can only react to injury in a limited number of ways, lesions that were thought at one time to be a specific clinicopathologic entity, for example, DIP, now evoke an ever-expanding differential diagnosis. In applying diagnostic criteria emphasis must be placed on the areas of overlap among tissue reactions as well. Specific agents may cause changes that are described as common for that agent, but a given patient may react with a variation or in a distinctly uncommon manner. There is enormous potential in this field for the laboratory investigation of drug injury.(ABSTRACT TRUNCATED AT 400 WORDS)

Amiodarone↗
PubMed1989

Altered function of protein kinase C and cyclic adenosine monophosphate-dependent protein kinase in a cell line derived from a mouse lung papillary tumor.

Two serine/threonine protein kinases were compared in C10, a clone from the nontumorigenic NAL IA cell line derived from normal mouse lung epithelium, and PCC4, a cell line derived from a mouse lung adenoma. C10 cells are contact inhibited, whereas PCC4 cells are not. Upon treatment with the phorbol ester, 12-O-tetradecanoylphorbol-13-acetate (TPA), the normally flattened C10 cells round up, while the normally bipolar, rounded PCC4 cells flatten out. Three proteins of 14,000, 20,000 and 116,000 molecular weight were phosphorylated in TPA-treated particulate fractions but not in untreated particulate fractions of PCC4 cells. In contrast, TPA caused a generalized increase in the phosphorylation of most membrane proteins in C10 cells. Cytosolic protein kinase C (PKC) specific activity was lower in PCC4 cells than in C10 cells, but particulate PKC activity was similar in the two cell lines. Both measurements of PKC activity and immunoblotting assays using anti-PKC antisera showed increased particulate PKC in TPA-treated C10 cells resulting from a quantitative translocation of PKC molecules from cytoplasm to plasma membrane. This PKC response to TPA was attenuated in PCC4 cells. While PCC4 particulate PKC activity was substantially increased after TPA treatment, PKC activity decreased only slightly in cytosolic fractions of TPA-treated PCC4 cells. Immunoblots of TPA-treated PCC4 cells showed a decline in cytosolic PKC content and increased particulate PKC concentration, but these changes were not of the same magnitude as the activity changes. This may represent an unmasking of latent PKC activity since particulate PKC activity in TPA-treated PCC4 cells was inhibited by staurosporine, a specific inhibitor of PKC when used at nanomolar concentrations. In addition, PCC4 cells had less mRNA coding for the R1 regulatory subunit of cyclic AMP (cAMP)-dependent protein kinase (PKA) than C10 cells, as determined by Northern blotting using an R1 alpha cDNA probe. Consistent with this result, photolabeling with 8-azido-[32P]cAMP, a photoaffinity analog of cAMP, revealed that R1 from PCC4 cells incorporated less analogue than R1 from C10 cells. PKA-specific activity also was lower in PCC4 cells than in C10 cells. Thus, deficiencies in protein kinases which mediate the effects of diacylglycerol and cAMP second messengers were observed in neoplastic lung cells. This may dampen the responsiveness of PCC4 cells to extracellular signals that regulate cell growth and cell-cell interactions.

Animals↗
PubMed1989

The rat as an experimental animal.

The development and characterization of many inbred, congenic, and recombinant strains of rats in recent years has led to the detailed genetic description of this species, especially in regard to its major histocompatibility complex. This information has contributed substantially to the study of comparative genetics and has greatly enhanced the utility of the rat in a variety of areas of biomedical research. This article focuses on the use of the rat in immunogenetics, transplantation, cancer-risk assessment, cardiovascular diseases, and behavior.

Animals↗
PubMed1989

S-phase block and cell death in human lymphoblasts exposed to benzo[a]pyrene diol epoxide or N-acetoxy-2-acetylaminofluorene.

The relationship between perturbation of the cell cycle and induction of cell death by benzo[a]pyrene diol epoxide (BPDE) or N-acetoxy-2-acetylaminofluorene (AcAAF) in exponentially proliferating T5-1 human lymphoblastoid cells was studied. Both BPDE and AcAAF caused cells to accumulate in the S phase of the cell cycle. Perturbation of the cell cycle preceded reduction of cell viability and was associated with inhibition of population growth. Effects on each of the three parameters were noted during the first population doubling, suggesting that they occurred during the first cell cycle after exposure. BPDE-exposed cells accumulated initially in early to mid-S phase and then moved parasynchronously through the remainder of this phase. In contrast, AcAAF-exposed cells accumulated uniformly at all points of the S phase. High doses of either compound froze cell cycle progression, completely inhibited population growth, and killed nearly all cells in the population. Our results suggest that perturbation of DNA replication mediates cell death after exposure to doses of either chemical that cause less than complete inhibition of cell proliferation. However, additional processes, such as perturbation of transcription, may be involved in lethality after exposure to doses that immediately and completely inhibit population growth.

2-Acetylaminofluorene↗