The differential expression of N-cadherin and E-cadherin distinguishes pleural mesotheliomas from lung adenocarcinomas.

Malignant mesotheliomas are highly aggressive tumors that develop most frequently in the pleura of patients chronically exposed to asbestos. The distinction between malignant mesotheliomas and tumors of epithelial origin, particularly peripheral lung adenocarcinoma, can be difficult despite the use of immunocytochemical markers and other diagnostic tools. During embryonic development the cadherin cell-cell adhesion molecules participate in the segregation of cells into different tissues.

Increased frequency of spontaneous skin tumors in transgenic mice which overexpress ornithine decarboxylase.

Ornithine decarboxylase, a critical regulatory enzyme for polyamine biosynthesis, is highly inducible by growth-promoting stimuli in mouse epidermis but the enzyme level is only transiently elevated due to rapid turnover of the protein. Here we report that constitutive overexpression of the enzyme in the skin of transgenic mice causes several phenotypic abnormalities. Effects observed include development of dermal follicular cysts, excessive skin wrinkling, enhanced nail growth, alopecia, and spontaneous tumor development.

Cell division does not increase transepithelial permeability of LLC-PK1 cell sheets.

The transepithelial electrical resistance (TER) across LLC-PK1 cell sheets is unstable for several days postseeding, even when the cells are trypsinized from a previously confluent culture and replated at confluent density. We therefore followed the TER of LLC-PK1 cells plated at confluent density to elucidate characteristics of the TER fluctuations after plating of the cells. Control cultures reached a maximum TER of 1800 omega.

Interaction of alpha-actinin with the cadherin/catenin cell-cell adhesion complex via alpha-catenin.

Cadherins are Ca(2+)-dependent, cell surface glycoproteins involved in cell-cell adhesion. Extracellularly, transmembrane cadherins such as E-, P-, and N-cadherin self-associate, while intracellularly they interact indirectly with the actin-based cytoskeleton. Several intracellular proteins termed catenins, including alpha-catenin, beta-catenin, and plakoglobin, are tightly associated with these cadherins and serve to link them to the cytoskeleton.

Association between high levels of ornithine decarboxylase activity and favorable prognosis in human colorectal carcinoma.

Several studies have documented increased expression of ornithine decarboxylase (ODC) in neoplastic colorectal tissue versus normal-appearing colonic mucosa. The present study was undertaken to determine whether there is an association between the degree of overexpression of ODC in colorectal carcinomas and survival in a series of 74 patients. A high level of tumor ODC expression was found to be significantly associated with greater survival in our patient series.

Sodium-independent carrier-mediated inositol transport in cultured renal epithelial (LLC-PK1) cells.

In addition to the concentrative, Na(+)-dependent inositol transport system demonstrated in many cell types, carrier-mediated, Na(+)-independent inositol transport is also shown to exist in LLC-PK1 renal epithelia. Inhibition of inositol uptake in Na(+)-free saline by 0.1 mM phloretin, and self-inhibition by net concentrations of inositol exceeding 10 mM, demonstrate the carrier-mediation of the Na(+)-independent uptake and distinguish it from flux through anion channels.

Expression and modulation of protein kinase C isoforms in differentiation-competent and differentiation-resistant erythroleukemic cells.

We have investigated eight of the protein kinase C (PKC) isoforms in Friend virus immortalized erythroleukemia cells. Using Western analysis, we detected the presence of the alpha, delta, epsilon, zeta and theta isoforms with no beta, gamma eta. We compared levels and modulations of these isoforms among 2 lines with different susceptibilities to DMSO-induced differentiation, a cell line rendered differentiation resistant by constitutive expression of an exogenous c-myb gene and cell lines naturally resistant to differentiation.

UV-light induces delayed mutations in Chinese hamster cells.

The possibility was examined that mutational events at the glucose 6-phosphate dehydrogenase locus can be delayed for significantly more than one or two cell divisions following treatment of Chinese hamster cells with UV light. To detect these later mutant events, the proportion of G6PD-mutant cells in a colony was obtained by replating cells from a single colony 5-7 days after UV irradiation and staining the resulting colonies for G6PD activity. Eight colonies out of a total of 1657 colonies from the treated population yielded G6PD-negative colonies upon replating, while no mutant clones were obtained from 947 colonies grown from untreated cells.

Regional localization of the XRCC4 human radiation repair gene.

To map the XRCC4 human DNA repair gene subchromosomally, a gamma-ray-resistant human:XR-1 hamster hybrid cell containing fragments of human chromosome 5 and the pSV2neo plasmid was lethally irradiated and fused with the gamma-ray-sensitive XR-1 mutant cell. After selection for G418 resistance, 2 of a total of 76 hybrids retained wildtype gamma-ray resistance. FISH analysis of normal human lymphocytes using DNA from the two resistant hybrids as probes produced a common region of hybridization at 5q13-q14, suggesting that the XRCC4 gene is in this region of chromosome 5.

The protein kinase C inhibitor, bisindolylmaleimide, inhibits the TPA-induced but not the TNF-induced increase in LLC-PK1 transepithelial permeability.

The transepithelial paracellular permeability of an epithelium formed by LLC-PK1 cells increases upon activation of protein kinase C (PKC) by the phorbol ester tumor promoter, TPA, or in response to the cytokine tumor necrosis factor-alpha (TNF). Until recently, however, we have not been able to inhibit the permeability effects of TPA or TNF using any of the currently available serine-threonine kinase inhibitors. In this study we report the treatment of epithelial cell sheets with the selective PKC inhibitor bisindolylmaleimide, GF109203X, completely prevents the TPA-induced but not the TNF-alpha induced increase in tight junction permeability.

Role of ornithine decarboxylase in epidermal tumorigenesis.

Ornithine decarboxylase (ODC) plays a key role in the biosynthesis of polyamines, which are necessary for cell growth and differentiation. ODC expression is very tightly controlled in all normal cells; however, regulation of its expression is altered in many tumor cells resulting in much higher basal levels of ODC in tumors. To investigate the potential role of ODC overexpression in epidermal tumorigenesis, we constructed a replication-defective retroviral vector to overexpress a truncated ODC protein in epidermal cells.

cAMP modulates transepithelial resistance response of LLC-PK1 renal epithelia to tumor necrosis factor.

For "leaky" epithelia the transepithelial resistance (Rt) is an electrophysiological measure of the paracellular pathway within the epithelial barrier. The Rt across a monolayer of LLC-PK1 porcine renal epithelial cells is specifically an inverse measure of paracellular transepithelial permeability and displays a multiphasic and reversible response to the cytokine tumor necrosis factor-alpha (TNF). The Rt response to TNF can be inhibited by the nonhydrolyzable adenosine 3',5'-cyclic monophosphate (cAMP) analogue, dibutyryl-cAMP.

Constitutive c-myb expression in K562 cells inhibits induced erythroid differentiation but not tetradecanoyl phorbol acetate-induced megakaryocytic differentiation.

K562 cells were stably transfected with a plasmid vector constitutively expressing a full-length human c-myb gene. Parental cells possess the dual potential of inducibility of cellular differentiation along two lineages, i.e.

Adequacy of continuous ambulatory peritoneal dialysis: morbidity and mortality in chronic peritoneal dialysis.

Mortality for hemodialysis patients tends to be in excess of 20% per year, and it is generally agreed that outcome for continuous ambulatory peritoneal dialysis patients is comparable. Several investigators have suggested recently that continuous ambulatory peritoneal dialysis, as commonly practiced, may not provide adequate therapy, especially for larger patients and for those with no residual renal function. Unfortunately, a dose-response curve relating the amount of dialysis delivered and clinical outcome for continuous ambulatory peritoneal dialysis patients has not been constructed.

Challenges and barriers to managing quality in an end-stage renal disease facility.

The End-Stage Renal Disease Program is underfunded and overregulated. Objective parameters of end points of care do not correlate to specific clinical practice patterns. We do not have consensus between payers, providers, and patients as to what the objectives of the End-Stage Renal Disease Program are or should be.

Absence of a Ku-like DNA end binding activity in the xrs double-strand DNA repair-deficient mutant.

Double-strand DNA break repair is important in maintaining the genetic integrity of the genome. Using a mobility shift assay, we find that a protein, or complex of proteins, that is present in mammalian and yeast cells binds to the ends of double-strand DNA and renders the ends resistant to exonuclease digestion. Additionally, a mammalian DNA double-strand repair-deficient mutant, xrs, has no observable DNA end binding activity, while a revertant cell has wild-type activity.

Increased sensitivity to DNA-alkylating agents in CHO mutants with decreased poly(ADP-ribose) polymerase activity.

Using a replica-plating procedure and a 32P-NAD+ permeable cell-screening assay, we have isolated a CHO mutant, PADR-9, which displays approximately 17% of the wild-type level of poly(ADP-ribose) polymerase activity. Biochemical analysis of the mutant using activity, Western, and Northern blot techniques indicate that relative to its parent cell, the mutant's enzyme activity, antibody recognition, and mRNA levels have been reduced to approximately the same extent. These results are consistent with a mutation in the PADR-9 cell which has resulted in a reduction in enzyme synthesis due to reduced mRNA synthesis and/or stability.

N-cadherin involvement in cardiac myocyte interaction and myofibrillogenesis.

N-cadherin is a cell-surface, Ca(2+)-dependent adhesion molecule found in intercalated disks and extrajunctional sites in the myocardium. In this paper we show that antibodies specific for N-cadherin inhibit the contraction of both interacting and single myocytes isolated from embryonic chicken hearts. Quantitative electron microscopy revealed that anti-N-cadherin significantly decreases cell-cell contact between interacting myocytes, consistent with a role for N-cadherin as a cell-cell adhesion molecule.

Long-term effects of tumor necrosis factor on LLC-PK1 transepithelial resistance.

Renal epithelial LLC-PK1 cell sheets incubated with tumor necrosis factor (TNF) undergo an acute, spontaneous, and rapidly reversible decrease in transepithelial resistance (TER). (Mullin et al., 1992).

Rhabdomyosarcoma-derived cell lines exhibit aberrant expression of the cell-cell adhesion molecules N-CAM, N-cadherin, and cadherin-associated proteins.

Many cancer cells show aberrant adhesion properties that likely contribute to tumorigenesis, invasion, and metastasis. Here, we examine three MyoD-expressing, rhabdomyosarcoma-derived human cell lines (RD, A-204, and HS 729) for their expression of the neural cell adhesion molecule (N-CAM), N-cadherin, and the cadherin-associated proteins, alpha-catenin, beta-catenin, and plakoglobin, using specific antibodies and immunoblotting and immunocytochemical methods. Normally, during the formation of skeletal muscle, both N-CAM and N-cadherin are expressed and participate in mediating myoblast adhesion accompanying cell fusion.

Effects of epidermal growth factor versus phorbol ester on kidney epithelial (LLC-PK1) tight junction permeability and cell division.

In polarized epithelia, the tight junctions (TJs) constitute a barrier that controls the paracellular flux of solutes and water. In the renal LLC-PK1 cells, the TJ permeability can be correlated directly with the unidirectional transepithelial flux of solutes, such as D-mannitol, which have negligible affinity for cell membrane transport systems, and inversely to the transepithelial electrical resistance (TER). This study investigates TJ permeability and cell proliferation in LLC-PK1 cells treated with the phorbol ester, tumor promoter, 12-O-tetradecanoylphorbol-13-acetate (TPA) or with epidermal growth factor (EGF), a mitogen without secondary carcinogenic effects.

Renal papillary necrosis in a hemodialysis patient.

We present the first case report of bilateral renal papillary necrosis developing in a patient on hemodialysis. A 37-year-old hypertensive male with chronic glomerulonephritis had a normal retrograde pyelogram one year prior to initiation of hemodialysis. After two years of maintenance dialysis, he presented with gross hematuria and was found to have extensive bilateral renal papillary necrosis.

Elevated ornithine decarboxylase activity, polyamines and cell proliferation in neoplastic and vacuolated liver cells of winter flounder (Pleuronectes americanus).

Liver neoplasms, including hepatocellular and cholangiocellular tumors, commonly occur in winter flounder (Pleuronectes americanus) caught from some chemically contaminated areas such as Boston Harbor. Hydropically vacuolated cells, very often associated with neoplasia in winter flounder liver, appear to represent the first cellular abnormality in animals that later develop frank neoplasms. The proliferative capacity of hydropically vacuolated cells was studied by analyzing both ornithine decarboxylase (ODC) activity and bromodeoxyuridine (BrdU) labeling indices.

Two methods for assaying DNA double-strand break repair in mammalian cells by asymmetric field inversion gel electrophoresis.

The rejoining of gamma-ray-induced DNA double-strand breaks (DSBs) in mammalian cells was measured after various doses of gamma rays by using a version of pulsed-field gel electrophoresis to elute fragments of DNA from an agarose plug into the lane of an agarose gel. Two approaches for measuring the kinetics of DNA repair were compared. In the first method, cells are irradiated and incubated at 37 degrees C in monolayers, after which the cells are suspended in agarose and DNA is isolated and subjected to electrophoresis.

Modulation of tumor necrosis factor-induced increase in renal (LLC-PK1) transepithelial permeability.

Tumor necrosis factor-alpha (TNF) causes a spontaneously reversible increase in tight junction permeability. TNF was the only cytokine tested that produced this effect. The effect on transepithelial permeability proceeds in four distinct phases: 1) a 60- to 90-min delay from time of application of TNF, 2) a rapid decrease in transepithelial resistance, 3) a recovery of transepithelial resistance to control level within 1 h, and 4) a further increase of transepithelial resistance above control levels.