Biomedical subjects

R E Stephens

Publications and source records attributed to R E Stephens.

At least 55 records · Page 3Linked to original sources

PubMed1994

Modifications of alkaline microgel electrophoresis for sensitive detection of DNA damage.

The alkaline microgel electrophoresis technique was modified to achieve a substantial increase in sensitivity for the detection of radiation-induced DNA damage in human lymphocytes. This increased sensitivity was achieved through: (1) the addition of free radical scavengers to the electrophoresis solution to reduce DNA damage generated during alkaline unwinding and electrophoresis; (2) the modification of the electrophoresis unit to achieve a more uniform electric field; (3) the use of YOYO-1, a DNA dye, producing fluorescence 500-fold more intense than ethidium bromide; and (4) the introduction of an image analysis system for the quantitation of DNA migration. In addition to increasing sensitivity, these modifications have increased the speed with which observations can be quantified, and improved reproducibility from experiment to experiment. In human lymphocytes, these modifications have resulted in an increased sensitivity of several fold, allowing the detection of DNA damage in the range of 50 mGy. This increased sensitivity for the detection of DNA damage should extend the utility of this technique.

Benzoxazoles↗

PubMed1994

Tubulin and tektin in sea urchin embryonic cilia: pathways of protein incorporation during turnover and regeneration.

Axonemal precursor tubulin is the major protein component of the detergent-soluble membrane/matrix fraction of sea urchin embryonic cilia. Its unusual abundance may reflect the rapid turnover of these cilia, a process that is further documented here. However, whether during induced regeneration or normal turnover and growth, most other newly synthesized axonemal proteins are not detectable in the membrane/matrix fraction, raising the question of how non-tubulin precursors transit the growing cilium to the distal tip where assembly is generally thought to occur. Three potential explanations were considered: (1) the assembly of these components is proximal; (2) their relative concentration is too low to detect; or (3) tubulin alone is conveyed via a membrane/matrix pathway while most other axonemal proteins are transported in association with the axoneme. Light microscope autoradiography of axonemes pulse-chase labeled with [3H]leucine showed relatively uniform labeling, with no evidence for proximal incorporation. Fully grown cilia and cilia at early stages of regeneration were isolated from labeled embryos, fractionated into membrane/matrix, axonemal tubulin and architectural remnant components, and their labeled protein compositions were compared. Heavily labeled axonemal proteins, most notably the integral microtubule doublet component tektin-A, were not detected in the membrane/matrix fraction of emerging cilia, even though nearly half of the total ciliary tubulin appeared in that fraction, arguing against membrane-associated or soluble matrix transit for the architectural proteins at low concentrations. However, after thermal fractionation of axonemes from growing cilia, labeled proteins characteristic of the architectural remnant dominated the solubilized microtubule fraction, supporting axoneme-associated transport of the non-tubulin proteins during growth, in contrast to a membrane/matrix pathway for tubulin.

Animals↗

PubMed1994

Environmental induction of tumor phenotype in a putative Kaposi sarcoma progenitor cell.

Many features of AIDS-related Kaposi sarcoma (AIDS-KS), e.g., multifocal lesional presentation at sites perfused by the microvasculature, suggest that AIDS-KS is initially a hyperplasia that subsequently progresses to a neoplasia. We propose that the unique AIDS environment, which contains high levels of circulating factors such as viral cytokines, is key in initiating the KS lesion. Further, we maintain that due to their physiological function, human microvascular endothelial cells (HMECs) are both likely target cells for the AIDS-related cytokines, and are putative AIDS-KS progenitor cells. Previously, we have shown that as a component of HMEC transition between proliferative and differentiated growth, HMECs modulate their nucleotide and glutathione levels. After attaining contact inhibition, HMECs enter a state of differentiation, which is characterized by cellular entrance into a G0, quiescent growth state, a decrease in cellular bioenergetic profiles, and spontaneous formation of microtubules. In contrast, when cultured in a "KS milieu", HMECs fail to differentiate. Instead, the "KS milieu" cultured cells assume a "growth relaxed" phenotype and demonstrate a lack of contact inhibition, loss of anchorage dependence, and retention of a "proliferative" bioenergetic profile despite culture confluence. Our results imply both that HMECs are responsive to AIDS-related cytokines, and that the local environment is key to instigating a relaxation of cellular growth controls.

AIDS-Related Complex↗

PubMed1993

Modulation of human microvascular endothelial cell bioenergetic status and glutathione levels during proliferative and differentiated growth.

During angiogenesis, formerly differentiated human microvascular endothelial cells (HMECs) return to a proliferative growth state. Many fundamental questions regarding HMEC function, such as how HMECs adapt to changes in bioenergetic requirements upon return to proliferative growth, remained unanswered. In this study, we evaluated whether modifications in HMEC bioenergetic profiles and glutathione (GSH) levels accompanied the cellular transition between differentiated and proliferative growth. To provide insight into the continuum of cellular adaptations that occur during this transition, we used a method recently developed in our laboratory that induces a state of morphological and functional predifferentiation in HMECs. Cellular morphology, in conjunction with flow cytometric DNA analyses and HMEC functional assays (the directed migration and intercellular association involved in microtubule formation) were employed to validate the HMEC culture state of growth. Analysis of the HPLC nucleotide profiles disclosed several findings common to all culture growth states. These uniform findings, e.g., cellular energy charges > 0.90, and highly reduced redox states, revealed that cultured HMECs maintain high rates of oxidative metabolism. However, there were also significant, culture growth state related differences in the nucleotide profiles. Proliferative HMECs were shown to possess significantly higher (relative to both large vessel endothelial cells, and differentiated HMECs) levels of GSH and specific nucleotides which were related with a return to the active cell cycle-ATP, GTP, UTP, and CTP, and NADPH. Further, the nucleotide profiles and GSH levels of the predifferentiated HMECs were determined to be intermediate between levels obtained for the proliferative and differentiated HMECs. The results of this study demonstrate that the capacity to modulate their cellular bioenergetic status during growth state transitions is one of the adaptations that enable HMECs to retain a growth state reciprocity. In addition, our findings also show that HMECs, especially during the proliferative growth state, are biochemically distinct from endothelial cells harvested from large vessels, and therefore suggest that HMECs are the cells of choice to employ when studying diseases that affect the human microvasculature.

Adolescent↗

PubMed1993

Protection of ROC-1 hybrid glial cells by polyethylene glycol following ATP depletion.

Oligodendroglia-glioma hybrid cells (ROC-1) subjected to inhibition of glycolytic and oxidative ATP synthesis undergo a sequence of changes, including ATP depletion, parallel processes of cell swelling and blebbing, and finally plasma membrane disruption and cell death. The morphological and biochemical changes that follow ATP depletion were studied in the presence and absence of polyethylene glycol (M(r) 8,000), a nonpermeant oncotic agent. Polyethylene glycol prevented cell swelling and membrane blebbing. It significantly delayed, but did not prevent, the release of lactate dehydrogenase into the medium; it did not affect the fall in [ATP]. These results suggest that osmotic cell swelling may be a contributing factor in the loss of cell viability when ROC-1 cells are depleted of ATP.

Adenosine Triphosphate↗

PubMed1992

Relationship between the depletion of O6-methylguanine-DNA methyltransferase by O6-methylguanine and the stimulation of DNA synthesis and growth of cultured chick hepatocytes.

O6-Methylguanine-DNA methyltransferase (O6-MT) has been described as a DNA repair enzyme that reverses alkylation damage at the O6 position of guanine in DNA. We demonstrate that the concentration of this protein decreases immediately prior to DNA synthesis in cultured chick hepatocytes. If intracellular levels are experimentally depleted by treatment of cultures with O6-methylguanine, DNA synthesis occurs as an associated resultant. This effect is dose dependent and can be followed by discernible morphological changes of organoids in culture. Increased and altered growth caused by O6-methylguanine was quantified and was also found to be dose dependent. Therefore, O6-MT may play a role in the regulation of DNA synthesis.

Animals↗

PubMed1992

Tubulin in sea urchin embryonic cilia: post-translational modifications during regeneration.

Tubulin is the major protein found in the membrane/periaxonemal matrix fraction of mature sea urchin embryonic cilia but its distribution and possible function during ciliary assembly are unknown. Hypertonic salt may be used to deciliate the embryos, allowing synchronous regrowth of cilia and subsequent deciliation of the regenerating embryos at various times. During the earliest stages of regeneration, the amounts of tubulin in the axoneme and membrane/matrix fractions are nearly equal, but the proportion of tubulin in the axoneme fraction increases coincident with the quasi-linear growth phase while the membrane/matrix tubulin remains constant. Antibodies to tyrosinated and detyrosinated alpha-tubulin show that both the membrane/matrix and axonemal tubulin fractions are primarily unmodified (i.e. tyrosinated) at the earliest stages of regeneration but are progressively and equally detyrosinated coincident with regeneration, approaching a final level of 50% C-terminal Glu. A monoclonal antibody to acetylated alpha-tubulin reveals that both tubulin fractions are equally and maximally acetylated at relatively early stages of regeneration. In contrast, three-times-repolymerized tubulin from either unfertilized eggs or midgastrula embryos is primarily tyrosinated (greater than 97%) and not detectably acetylated. These data suggest that membrane/matrix tubulin is a precursor to axonemal tubulin and that acetylation and detyrosination may be involved in partitioning tubulin among cytoplasmic, ciliary membrane/matrix, and 9 + 2 compartments.

Acetylation↗

PubMed1992

Dynein from serotonin-activated cilia and flagella: extraction characteristics and distinct sites for cAMP-dependent protein phosphorylation.

Serotonin, an activator of adenylate cyclase, stimulates motility in molluscan gill cilia and sperm flagella. To determine and compare potential targets of cAMP action, dynein was prepared from the lateral gill.cilia and sperm flagella of the mussel Mytilus edulis and the clam Spisula solidissima. In the flagella of both species, high-salt extraction removes about half of the ATPase activity, half of the alpha and beta heavy chains, and the outer arms. The dynein from both species sediments at 18-20 S, contains two or three intermediate chains, and three light chains. High-salt plus detergent removes most of the remaining dynein ATPase, alpha and beta heavy chains, and inner arms, also yielding a stable 18-20 S particle. In gill cilia of both species, high-salt extraction removes only 12-18% of the ATPase, up to 1/3 of the alpha heavy chains, an equivalent amount of beta heavy chain, and a subset of the outer arms. The dynein sediments at 18-20 S and, in Spisula, the heavy, intermediate, and light chains precisely co-sediment. High-salt plus detergent removes another 1/3 of the alpha heavy chains, an equivalent amount of beta heavy chain, and the remaining outer arms. The ATPase sediments mainly as a 13-14 S form showing considerable dissociation of co-sedimenting intermediate and light chains. The inner arms and at least half of the ciliary dynein ATPase activity remain unextractable, corresponding in mass mainly to an apparent beta heavy chain that is vanadate-cleavable. Cyclic AMP-dependent, calcium-independent phosphorylation takes place on specific dynein light chains in cilia but on only the dynein alpha heavy chain in flagella. Pre-activation of the flagella prevents subsequent addition of labeled phosphate. Phosphorylation has no effect on the steady-state ATPase properties. The single phosphate added to the flagellar alpha chain is located within the LUV1 vanadate photocleavage fragment. Considering the probable locus of the light chains and the site of the alpha heavy chain phosphorylation, both beyond the active site and toward the base of the molecule, these distinct phosphorylations may regulate dynein action by modulating arm flexibility or interaction.

Adenosine Triphosphate↗

PubMed1992

Sensitivity of human glioma and brain cells to natural killer cell lysis. Effects of serum concentration, epidermal growth factor, and time in culture.

Using an in vitro monolayer natural killer (NK) cytolysis assay, the authors examined the effects of serum concentration and epidermal growth factor (EGF) on sensitivity to NK cytolysis. It was found that target cells cultured in high concentrations of serum (10% fetal bovine serum (FBS)) had higher cytotoxicity levels than those in low serum concentrations (0% to 0.5% FBS). Exposure of target cells to EGF had no effect on their sensitivity to NK cytolysis. Both glioma cell lines showed decreased NK cell sensitivity with longer times in culture. The results of cytofluorometric studies on these cell lines indicate that the differences in NK cell sensitivity may reflect the growth fraction of the target population and that a population with a higher proportion of cycling cells is more susceptible to lysis by NK cells. Whether it is possible to separate the proliferative rate of these cells from their NK cell sensitivity is unknown, but worthy of consideration.

Blood↗

PubMed1991

Association of cellular thiol redox status with mitogen-induced calcium mobilization and cell cycle progression in human fibroblasts.

Human gingival fibroblast cultures were used to investigate the role of cellular thiol redox status in the mitogenic response. Increases in intracellular Ca2+ and cell cycle progression beyond G1 were followed as parameters of cellular mitogen-induced responses. Ethionine provided a G1 stage synchronization and altered the cellular redox poise as measured by the ratio NAD(P)H/NAD(P)+. Cultures harvested immediately after the 6 day ethionine low-serum synchronization showed a significant oxidation of their redox poise. Synchronized cultures, which were also glutathione (GSH) depleted, still showed an oxidized redox poise and significantly reduced GSH levels following a 24 hr incubation in drug-free, rich medium. Cellular reduced nicotinamide nucleotide levels correlated strongly (r = 0.995) with capacity to mobilize intracellular Ca2+ in response to basic fibroblast growth factor (bFGF). The sustained mitogenic response, as determined by cell cycle progression beyond G1, was also found to be interrelated with the cellular thiol redox status. Following a 24 hr recovery incubation in serum-rich medium, formerly synchronized cultures showed a rebound of their redox poise to a more reduced state and significant cell cycle progression beyond G1. In contrast, synchronized, GSH-depleted cultures did not progress and showed population distributions similar to those of cultures harvested immediately postsynchronization. Upon recovery of cellular GSH and reduced nicotinamide nucleotide levels, formerly GSH-depleted, growth-arrested cultures resumed cell cycle progression. The results suggest that the cellular response to specific mitogens is interrelated with the cellular thiol redox status. Cells that possess a thiol redox status below a threshold response point may have compromised Ca2+ sequestration and/or mobilization and therefore may be incapable of initiating the mitogen induced response cascade that culminates in cell cycle progression.

Calcium↗

PubMed1991

Preservation of natural endothelial cytopathogenicity of cytomegalovirus by propagation in endothelial cells.

Cytomegalovirus (CMV) is a source of major complications in immunosuppressed individuals, and endothelial involvement in CMV infection is well documented. Traditionally the virus has been propagated in fibroblasts, however this process may alter CMV's characteristics, thereby limiting the fibroblast model's utility as a research tool. In our efforts to develop a more accurate in vitro model of CMV/endothelial cell interaction, we have propagated a recent isolate (CMV VHL) through multiple passages in human umbilical vein endothelial cells (HUVE) and, collaterally in neonatal human dermal fibroblasts (NHDF). Infection of HUVE inoculated with either sub-strain of the virus was confirmed by CMV-specific in situ hybridization and by immunocytochemical staining for CMV antigens. Whereas infection of HUVE by substrain VHL/E (endothelial-raised) was accompanied by dramatic cytopathology resembling that observed clinically, the endothelial cytopathic potential of VHL/F (fibroblast-raised) was lost by its 20th passage in NHDF. Similarly, the ability of VHL/F to initiate sustained productive infection in HUVE was severely attenuated; plaque assay of culture supernatants and infected cell fractions, as well as virus-specific DNA polymerase assay of cell lysates, demonstrated progressive viral reproductive activity in VHL/E-inoculated HUVE, whereas VHL/F reproduction was barely detectable. Since properties of VHL/F bear strong resemblance to those of the fibroblast-raised AD169, these studies suggest that while the fibroblast adaptation process commonly employed in the propagation of CMV restricts the host range of the virus and attenuates its spectrum of cytopathic potential, endothelial-based propagation preserves the natural endothelial cytopathogenicity of the original isolate.

Antigens, Viral↗

PubMed1991

A microgel electrophoresis technique for the direct quantitation of DNA damage and repair in individual fibroblasts cultured on microscope slides.

We demonstrate by single-cell microgel electrophoresis that the 2 main techniques, trypsinization and scraping, used to collect normal diploid mammalian cells cultured in monolayer induce DNA damage. To minimize this potential interference with studies on DNA damage and repair, we have standardized the single-cell gel electrophoretic (SCG) technique for the in situ quantitation of DNA single-strand breaks and alkali-labile sites in cultured human-fibroblasts. To demonstrate the utility of this technique, human neonatal foreskin-derived fibroblasts were allowed to attach to frosted microscope slides and then either irradiated with X-rays (25-200 rad) or treated for 1 h with hydrogen peroxide (2.2-140.8 mumoles). Treatment with either agent induced a dose-dependent increase in DNA migration. At equal levels of DNA damage, cell-to-cell variability in DNA migration was more heterogeneous for hydrogen peroxide-treated cells than for X-irradiated cells. A time course study to evaluate the kinetics of DNA repair for X-ray (200 rad)-induced damage indicated that the damage was completely repaired within 2 h. Applications of this technique for in vitro toxicology are discussed.

Cell Adhesion↗

PubMed1991

Tubulin in sea urchin embryonic cilia: characterization of the membrane-periaxonemal matrix.

When the membranes of isolated embryonic cilia from three species of sea urchin are detergent-solubilized, the major proteins found are two equi-molar polypeptides comigrating with tubulin subunits. Cross-reactivity with a variety of tubulin antibodies confirms their identity. Calmodulin and other calcium-binding proteins are prominent minor constituents of the extract. Removal of the solubilizing detergent by adsorption to polystyrene beads, followed by a freeze-thaw cycle, produces membrane leaflets and vesicles of uniform bouyant density. Such reconstituted membranes incorporate most of the tubulin and minor proteins but not calmodulin. Equivalent cross-reactivity with antibodies to acetylated or detyrosinated alpha-tubulin indicates that the tubulin derived from the membrane-periaxonemal matrix and axoneme are indistinguishable from each other in terms of these posttranslational modifications but are distinct from the mainly unmodified tubulin of the embryonic cytoplasm. Pulse labeling with [3H]palmitate does not label either tubulin subunit but acylation does occur on a 190 x 10(3) Mr membrane protein. Its specific activity is essentially the same whether label is applied to embryos with existing or regenerating cilia, suggesting rapid ciliary membrane protein exchange or physical turnover. Using pulse-chase labeling with [3H]leucine during steady-state ciliary growth or induced regeneration in both normal and zinc-animalized embryos, the specific activity of the membrane-periaxonemal matrix-derived tubulin is initially higher than that of the axoneme but the degree of labeling equalizes in successive regenerations, consistent with derivation from a common pool. Many heavily labeled axonemal architectural proteins, such as tektin-A, are not reflected in the membrane-periaxonemal matrix fraction, suggesting that this fraction is not simply a pool of unassembled axonemal precursors.

Animals↗

PubMed1990

Filipin-sterol complexes in molluscan gill ciliated epithelial cell membranes: intercalation into ciliary necklaces and induction of gap junctional particle arrays.

Freeze-fracture electron microscopy has been used in conjunction with the antibiotic filipin to investigate possible differences in the distribution of sterols in ciliary and somatic cell membranes of scallop and mussel gill epithelial cells. Contrary to previous reports, we find that filipin-sterol lesions can occur among the strands of the ciliary necklace but they are partially excluded from the smooth neck region above the necklace where the membrane is tightly apposed to the axonemal microtubules. No obvious differences in filipin-sterol lesions occur in the membranes of mussel gill cilia of varying mechanical sensitivity. Although abundant in the apical plasma membrane, filipin-sterol complexes are rare within the membranes of microvilli. Filipin-sterol lesions form outside the loosely parallel particle strands of septate junctions, sometimes increasing their relative orderliness. At sufficiently high density, filipin-sterol protrusions within the plasma membrane result in mass aggregation of gap junctions, possibly through recruitment of unorganized connexons.

Animals↗

PubMed1990

Mechanical sensitivity and cell coupling in the ciliated epithelial cells of Mytilus edulis gill. An ultrastructural and developmental analysis.

Transmission electron microscopy has not provided strong evidence for gap junctions in Mytilus edulis gill tissue, in spite of extensive physiological evidence for coupled ciliary arrest in lateral cells and coupled activation in abfrontal cells. To investigate the kinds and relative distribution of cell junctions and also to determine whether ciliary membrane particle differences exist in these two types of oppositely mechanically sensitive cells, we analyzed the structure of these and two other ciliated cell types (frontal and laterofrontal) by freeze-fracture replication. Gap junctions occur in all four ciliated cell types, but they are relatively small and of variable morphology, often consisting of elongate, winding complexes of membrane particles. Statistically, such structures rarely would be recognized as gap junctions in thin sections. Gap junctions appear to be most abundant between the highly coupled abfrontal cells, minimal between laterofrontal cells, and not evident in the epithelial cells that separate coupled ciliated cell types. The ciliary necklaces of the mechanically activated abfrontal cilia are typically 4- or 5-stranded while those of the remaining three cell types are mainly 3-stranded. In developing gill tips, ciliated cells have abundant gap junctions and newly formed cilia have a full complement of necklace particles. Nascent lateral cilia are not mechanically sensitive, indicating that the acquisition of mechanosensitivity does not correlate with the presence of ciliary necklace or other membrane particles. Lateral and laterofrontal cells become sensitive to neurotransmitters soon after the appearance of the latter during development, but mechanosensitivity of both lateral and abfrontal cells arises substantially later.

Animals↗

PubMed1990

Inability of cytomegalovirus infection of cultured endothelial cells to induce HLA class II antigen expression.

Cytomegalovirus infection in the renal allograft recipient has been associated with the initiation of acute rejection. The mechanism of this induction is unknown. It may be related to renal tubular epithelial and endothelial expression of HLA class II antigens or a CMV immediate-early antigen that exhibits immunologic crossreactivity with HLA DR. In this study the ability of CMV to both infect and subsequently induce class II antigen expression on cultured human umbilical-vein endothelial cells (HUVEs), in the absence of cytokines, particularly gamma interferon, was tested. Individual HUVE cell lines were first proven to express HLA class II antigens in the presence of 10, 100, and 200 units of recombinant IFN-gamma as early as 24 hr postincubation by an immunohistochemical technique and by flow cytometry. These cell lines were successfully infected with CMV strains AD169 and CMV3 as determined by the presence of early and late viral antigens and CMV DNA. The degree of infection was dose and incubation-time dependent. Infection of HUVEs with these CMV strains and a nonattenuated clinical isolate failed to induce HLA DR, DP, or DQw1 expression in the absence of IFN-gamma. These findings support the hypothesis that endothelial cells in vivo may serve as reservoirs of CMV infection. They do not support the hypothesis that CMV produces an immediate-early antigen that has immunologic cross-reactivity with HLA DR. Furthermore, there is no support for the hypothesis that CMV independently induces HLA class II antigens in the absence of IFN-gamma.

Cells, Cultured↗

PubMed1989

Enhanced endothelial cytopathogenicity induced by a cytomegalovirus strain propagated in endothelial cells.

Endothelial involvement has been implicated in cytomegalovirus (CMV) infection, a source of major complications in immunosuppressed individuals (e.g., those with acquired immune deficiency syndrome [AIDS] and organ transplants). Traditionally, CMV has been grown in fibroblasts; however, propagation in these cells may alter characteristics of the virus. In developing an in vitro model system of CMV/endothelial cell interaction, we have addressed this issue by propagating a clinical isolate, CMV VHL 1, in human umbilical vein endothelial (HUVE) cells by serial cocultivation of heavily infected cultures with fresh HUVE monolayers and have compared its infectious properties with those of the fibroblast-raised strain, CMV AD169. In situ hybridization using a biotinylated DNA probe, as well as immunofluorescent staining for CMV-specific antigen, has confirmed infection of HUVE cells inoculated with either strain of the virus. Infection of HUVE by VHL was accompanied by dramatic cytopathology not observed in AD169-infected cells. Plaque assay of culture supernatants revealed greater virus production in VHL-infected HUVE as compared with equivalently inoculated fibroblasts. In contrast, AD169 production in inoculated fibroblasts exceeded that in HUVE. These studies demonstrate the suitability of cultured endothelial cells as a substrate for CMV propagation and suggest that a strain of virus thus propagated may offer an accurate model of CMV/endothelial cell interaction in human disease.

Cells, Cultured↗

PubMed1989

Sensitivity of glioma and fetal brain cell lines to natural killer cytolysis in a monolayer assay.

We have developed an in vitro assay for Natural Killer (NK) cell cytolysis of and binding to substrate attached human glioma and fetal brain cells. The monolayer cells were labeled with [51Cr] and the effectors were directly sedimented onto these substrate attached target cells. Using this method we screened several glioma and fetal brain cell lines. The results indicate that the majority of gliomas are NK resistant, however two of the tested lines (U251MG and BN3) were relatively sensitive as were the fetal brain cell lines (CHI and CHII). We conclude that this monolayer assay for NK cytotoxicity and binding of glioma targets is a reproducible and valid method for assessing NK sensitivity, and should have applications in the study of other cultured solid tumors and substrate attached cells.

Brain↗