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The gene-sensing properties of sensor films made of a terthiophene-conducting polymer, poly(3-((2':2'', 5'':2'''-terthiophene)-3''-yl)acrylic acid) (PTAA), were evaluated using electrochemical impedance spectroscopy for films in their reduced and oxidised states with and without the Fe(CN)(6)(3-/4-) redox probe (RP) in dilute tris-EDTA buffer. Porous films of PTAA were prepared and attached to an oligonucleotide sequence specific to the Salmonella virulence gene InvA. These films could be described with a dual transmission line model in which the polymer conductivity was increased as a consequence of surface binding of complementary DNA. The effect is analogous to that reported for silicon nanowires and field-effect transistors in dilute electrolyte modified by charge exchange across the polymer-electrolyte interface. As a result, gene sensing could be conveniently observed as a change in the impedance phase angle at a fixed frequency.

Oval cell activation, as part of the regenerative process after liver injury, involves considerable cell-matrix interaction. The matricellular protein, connective tissue growth factor (CTGF), has been shown to be critical for oval cell activation during liver regeneration following N-2-acetylaminofluorene/partial hepatectomy. To understand the mode of action of CTGF during this process, N-terminal CTGF was used as bait to screen a yeast two-hybrid complementary DNA library specific for regenerating livers with massive oval cell presence. Fibronectin (FN), a prominent component of hepatic extracellular matrix (ECM), was found to specifically bind to a new site on CTGF. In addition to module IV, this study showed that module I of CTGF was sufficient for binding to FN in both solid-phase in vitro binding assays and immunoprecipitation. Immunofluorescent staining revealed a dynamic ECM remodeling characterized by an FN-concentrated provisional matrix during oval cell–aided liver regeneration. Abundant CTGF protein was colocalized with FN in the provisional matrix. When expressed as recombinant proteins and immobilized on plastic surfaces, modules I and IV of CTGF were selectively adhesive to thymus cell antigen 1–positive (Thy1+) oval cells, stellate cells, and sinusoidal endothelial cells but not to hepatocytes. The adhesion of these two modules on Thy1+ oval cells required heparan sulfate proteoglycan and integrin α5β1. Recombinant CTGF promoted an integrin α5β1–dependent migration but not proliferation on Thy1+ oval cells. Conclusion: Modules I and IV enabled the linkage of CTGF to FN and activated hepatic cells. Through these bindings, CTGF on the FN-concentrated provisional matrix promoted cell adhesion and migration, thereby facilitating oval cell activation. (HEPATOLOGY 2007.)

Modern medicine has conquered an enormous spectrum of health concerns, from the neonatal to the geriatric, the chronically ill to the acutely injured. Among the unmet challenges remaining in modern medicine are inborn disorders of metabolism within the liver. Such inherited metabolic disorders (IMDs) often leave an otherwise healthy individual with a crippling imbalance. As the principal regulator of the body's many metabolic pathways, malencoded hepatic enzymes can drastically disrupt homeostasis throughout the entire body. Severe phenotypes are usually detected within the first few days of life, and treatments range from palliative lifestyle modifications to aggressive surgical procedures. While orthotopic liver transplantation is the single last resort "cure" for these conditions, research during the past few years has brought new therapeutic technologies ever closer to the clinic. Stem cells, therapeutic viral vectors, or a combination thereof, are projected to be the next, best, and final cure for IMDs, which is well-reflected by this generation's research initiatives.

Stem cells represent the key to tissue genesis, regeneration, and turnover. This notion has spawned the concept of regenerative medicine, or stem cell based therapies to supplement degenerating or damaged tissues. However, stem cells may also represent a preferential target of carcinogens. The unique ability of stem cells to self-renew and to differentiate into multiple phenotypes implies that all stem cells share a common transcriptional signature. A better knowledge of the stem cell transcriptome appears to be fundamental to fully achieve the potential of regenerative medicine, and may lead to new strategies for cancer prevention and treatment. Elucidation of the transcriptional programming and molecular mechanisms which direct stem cell self-renewal, differentiation, and tumorigenesis should provide key insights into deciphering exactly how “stemness” is maintained, as well as the molecular basis of cell plasticity and cancer development. cDNA and oligonucleotide microarrays are the most accessible transcriptome profiling methods to date, providing the unique opportunity to compare global gene expression patterns among different cell populations. Microarray technologies have been applied to three major areas of stem cell research: maintenance of pluripotency, development of uniform and regulated differentiation, and microenvironment analyses. The aim of the present review is to summarize state-of-the-art transcriptional profiling of different stem cell lines, cancer stem cells, and the niches these cells occupy in vivo.

Subsequent to an initiating event, tumor promotion requires sustained cell proliferation to allow for progressive accumulation of pro-oncogenic mutations. The unique characteristics of stem cells would seem to implicate these cells as particularly suitable targets for carcinogens. Several lines of evidence suggest that tumors harbor a small population of cancer stem cells (CSC) which both give rise to the bulk of the tumor and are tumorigenic in experimental models. Mounting evidence suggests that these cells are responsible for re-growth of a tumor following unsuccessful treatment and for the establishment of metastases. The concept of CSC has been demonstrated in several human cancers including leukemia, breast, prostate, lung, and brain tumors. Taken together, the properties of CSC suggest that they are appropriate targets for cancer therapies. Such treatments would require a deep understanding of the CSC origin, molecular profile, and interaction with the local microenvironment. This report will summarize what is currently known regarding CSC, with particular emphasis on hepatic cancers, the cellular origin of liver tumors, and the role of liver stem cells and their niche in hepatocarcinogenesis.

Introduction: Connective tissue growth factor (CTGF) is a secreted pro-angiogenic protein within the CCN (Cyr61/CTGF/Nov) family and modulates multiple angiogenic pathways through its broad binding ability to cysteine knot motifs presents in key angiogenic factors including vascular endothelial growth factor (VEGF)-A. Overexpression of CTGF has been found in many cancers such as Lewis lung carcinoma (LLC), cholangiocarcinoma (CC), and hepatocellular carcinoma (HCC). In an effort to understand the molecular action of CTGF, we identified a disintegrin and metalloproteinase with thrombospondin type I repeat 7 (ADAMTS7) as a CTGF binding protein in yeast two-hybrid analysis. This enzyme belongs to the ADAMTS family capable of cleaving extracellular matrix (ECM) components and extracellular regulatory molecules. Here, we show that ADAMTS7 binds to and degrades CTGF during cancer development. Methods: Adamts7 knockout mice were used to investigate the importance of ADAMTS7 in CTGF interaction and cleavage during LLC development. Adamts7+/+ and Adamts7−/− mice were subcutaneously implanted with LLC cells. Tumor growth was quantitatively measured within two weeks after implantation. Tumor angiogenesis was assessed utilizing a microvascular density assay. In addition, Adamts7 expression was tracked via X-gal staining of LLC tumors grown in Adamts7−/− mice that contained a LacZ trap-in cassette in the targeted Adamts7 allele. VEGF-A, CTGF, and ADAMTS7 were determined at both the mRNA and protein levels. Results: Adamts7 induction as indicated by the β-galactosidase activity in X-gal staining was found in intra-tumor stromal cells of LLC tumors grown in Adamts7−/− mice. The association of CTGF and ADAMTS7 proteins in protein lysates of LLC tumors grown in Adamts7+/+ mice was confirmed in immunoprecipitation assays. Higher levels of VEGF-A, CTGF and ADAMTS7 mRNAs were found in LLC tumors from Adamts7−/− animals as compared to Adamts7+/+ controls. Slower rate of CTGF turnover, faster growth of LLC tumors, and higher microvascular density were also found in Adamts7−/− animals than controls. Conclusion: These observations confirmed the binding and processing of CTGF by ADAMTS7 during LLC growth. The host-derived ADAMTS7 appears to regulate CTGF turnover and provides a protective effect towards aberrant LLC tumorigenesis and angiogenesis. Citation Format: Liya Pi, Bryon E. Petersen. Interaction between connective tissue growth factor and a disintegrin and metalloproteinase with thrombospondin type I repeats 7 during cancer development. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2388. doi:10.1158/1538-7445.AM2015-2388

Stromal cell-derived factor-1 (SDF-1) is known to play an essential role in the regulation of stem/progenitor cell trafficking. During hepatic stem, or oval, cell activation, SDF-1 has been reported to be up-regulated within the liver, implying a possible role in oval cell-aided liver regeneration. In the present study, SDF-1 expression was knocked down in the liver of 2-acetylaminofluorene/partial hepatectomy-treated rats using short interfering RNA delivered by recombinant adenovirus. The oval cell response was compromised in these animals, as evidenced by a decreased number of OV6-positive oval cells. In addition, knockdown of SDF-1 expression caused a dramatic decrease in alpha-fetoprotein expression, implying impaired oval cell activation in these animals. Terminal deoxynucleotidyl transferase-mediated dUTP nick-end-labeling assay showed no significant apoptosis related to SDF-1 suppression. Instead, as revealed by Ki67 immunohistochemistry, the suppression of SDF-1 resulted in decrease of hepatic cell proliferation, implying the repair process had been inhibited in these animals. These results indicate that SDF-1 is an essential molecule needed in oval cell activation.

Background & Aims: Hepatic regeneration is a heterogeneous phenomenon involving several cell populations. Oval cells are considered liver stem cells, a portion of which derive from bone marrow (BM). Recent studies have shown that granulocyte–colony stimulating factor (G-CSF) may be effective in facilitating liver repair. However, it remains unclear if G-CSF acts by mobilizing BM cells, or if it acts locally within the liver microenvironment to facilitate the endogenous restoration program. In the present study, we assessed the involvement of G-CSF during oval cell activation. Methods: Dipeptidyl-peptidase-IV–deficient female rats received BM transplants from wild-type male donors. Four weeks later, rats were subjected to the 2-acetylaminofluorene/partial hepatectomy model of oval cell–mediated liver regeneration, followed by administration of either nonpegylated G-CSF or pegylated G-CSF. Control animals did not receive further treatments after surgery. The magnitude of oval cell reaction, the entity of BM contribution to liver repopulation, as well as the G-CSF/G-CSF–receptor expression levels were evaluated. In addition, in vitro proliferation and migration assays were performed on freshly isolated oval cells. Results: Oval cells were found to express G-CSF receptor and G-CSF was produced within the regenerating liver. G-CSF administration significantly increased both the magnitude of the oval cell reaction, and the contribution of BM to liver repair. Finally, G-CSF acted as a chemoattractant and a mitogen for oval cells in vitro. Conclusions: We have shown that G-CSF facilitates hepatic regeneration by increasing the migration of BM-derived progenitors to the liver, as well as enhancing the endogenous oval cell reaction.

Background & Aims: The ability of the bone marrow cells to differentiate into liver, pancreas, and other tissues led to the speculation that these cells might be the source of adult stem cells found in these organs. The present study analyzed whether the bone marrow cells are a source of hepatic oval cells involved in rat liver regeneration induced by 2-acetylaminofluorene (2-AAF) and 70% partial hepatectomy (PHx). Methods: Three groups of mutant F344 dipeptidyl peptidase IV–deficient (DPPIV−) rats were required for the study. Groups A and B received the mitotic inhibitor monocrotaline, followed by male F344 (DPPIV+) bone marrow transplantation. Next, group A received PHx only, while group B received the 2-AAF/PHx required for the oval cell activation. The last group C was used to analyze the effects of monocrotaline on transplanted bone marrow cells. These rats underwent transplantation with bone marrow cells and were then treated with monocrotaline. Subsequently, the animals were treated with 2-AAF/PHx. Results: In group A, DPPIV+ hepatocytes were found in the liver. Group B showed that approximately 20% of the oval cell population expressed both donor marker (DPPIV) and α-fetoprotein, and some differentiated into hepatocytes. In contrast, animals in group C failed to significantly induce oval cells with the donor DPPIV antigen. In addition, X/Y-chromosome analysis revealed that fusion was not contributing to differentiation of donor-derived oval cells. Conclusions: Our results suggest that under certain physiologic conditions, a portion of hepatic stem cells might arise from the bone marrow and can differentiate into hepatocytes.

Embryonic stem (ES) cells have been proposed to be a powerful tool in the study of pancreatic disease, as well as a potential source for cell replacement therapy in the treatment of diabetes. However, data demonstrating the feasibility of using pancreatic islet-like cells differentiated from ES cells remain controversial. In this study we characterized ES cell-derived insulin-expressing cells and assessed their suitability for the treatment of type I diabetes. ES cell-derived insulin-stained cell clusters expressed insulin mRNA and transcription factors associated with pancreatic development. The majority of insulin-positive cells in the clusters also showed immunoreactivity for C-peptide. Insulin was stored in the cytoplasm and released into the culture medium in a glucose-dependent manner. When the cultured cells were transplanted into diabetic mice, they reversed the hyperglycemic state for approximately 3 weeks, but the rescue failed due to immature teratoma formation. Our studies demonstrate that reversal of hyperglycemia by transplantation of ES cell-derived insulin-producing cells is possible. However, the risk of teratoma formation would need to be eliminated before ES cell-based therapies for the treatment of diabetes are considered.

The transplantation of pancreatic beta cells or hepatocytes represents a potential therapeutic approach for type I diabetes and inherited liver diseases, respectively. Furthermore, acquired liver diseases, particularly acute hepatic failure due to toxic or viral injury, have been treated in limited clinical trials with fetal and adult hepatocytes. However, a major limitation is the insufficient amount of beta cells and hepatocytes available for grafts. Alternative sources of these cells have yet to be determined. During the past few years, progress has been made in the development of new strategies to produce mature beta cells and hepatocytes. In this review, we outline the current state of scientific understanding and controversy regarding the properties of embryonic and adult stem cells in the field of hepatobiliary and pancreatic diseases. Our objective is to provide a framework of understanding for the challenges behind translating fundamental stem cell biology into clinical therapies.

Fouling of contact lenses is often due to tear protein diffusion into and aggregation within the contact lens material. These processes can diminish water and oxygen diffusion and create optical cloudiness of the lens. In order to understand the interactions between proteins and hydrogel contact lens materials a study was designed to measure the diffusivity of two model proteins within hydrogel films of varying composition using fluorescence correlation spectroscopy (FCS). Diffusion of human serum albumin (HSA) and apoferritin (aFER) was examined in a range of ~20 μm thick poly(acrylamide) (pAA) and poly(2-hydroxyethyl methacrylate) (pHEMA) hydrogels. Protein diffusivity was measured as a function of depth position within each hydrogel film. The characteristic diffusion time for two proteins in pHEMA hydrogels increased relative to both their diffusivity in solution and in pAA hydrogels, indicating that the protein-pHEMA interaction rather than the degree of hydrogel crosslinking is responsible for the observed effects. The resulting spatial representation of the molecular diffusion of proteins into and interaction with hydrogel materials builds a basis on which to conduct similar studies using commercial contact lens samples.

Recent findings suggest that bone marrow (BM) cells have the capacity to differentiate into a variety of cell types including endocrine cells of the pancreas. We report that BM derived cells, when cultured under defined conditions, were induced to trans-differentiate into insulin-producing cells. Furthermore, these insulin-producing cells formed aggregates that, upon transplantation into mice, acquired architecture similar to islets of Langerhans. These aggregates showed endocrine gene expression for insulin (I and II), glucagon, somatostatin and pancreatic polypeptide. Immunohistochemistry also confirmed that these aggregates were positive for insulin, somatostatin, pancreatic polypeptide and C-peptide. Also, Western and ELISA analysis demonstrated expression of proinsulin and/or secretion of active insulin upon glucose challenge. Subcapsular renal transplantation of these aggregates into hyperglycemic mice lowered circulating blood glucose levels and maintained comparatively normal glucose levels for up to 90 days post-transplantation. Graft removal resulted in rapid relapse and death in experimental animals. In addition, electron microscopy revealed these aggregates had acquired ultrastructure typically associated with mature beta (beta) cells. These results demonstrate that adult BM cells are capable of trans-differentiating into a pancreatic lineage in vitro and may represent a pool of cells for the treatment of diabetes mellitus.

Meeting on Signal Transduction Determining the Fate of Stem Cells

Although the existence of the hepatic oval cell (HOC), the liver stem cell has been known for almost 70 years, little is known about the potential for this adult stem cell to trans-differentiate into cells of other tissues. While their origin remains enigmatic, HOCs share many similarities with hematopoietic stem cells. Recent studies have revealed that a small percentage of HOCs can arise from a bone marrow-derived stem cell source. Here we report that, like bone marrow stem cells, HOCs can survive transplantation to the neonatal mouse brain and show signs of trans-differentiation by adopting the morphology and antigenic phenotype of both macro- and microglia cells. Trans-differentiated microglia cells were functional, showing active phagocytosis when cotransplanted with latex microbeads in vivo. In addition to glial markers, a small number of transplanted HOCs were immunopositive for neuronal markers, but displayed ambiguous phenotype, making their characterization difficult.

Background and aim: Liver regeneration after severe liver damage depends in part on proliferation and differentiation of hepatic progenitor cells (HPCs). Under these conditions they must be able to withstand the toxic milieu of the damaged liver. ATP binding cassette (ABC) transporters are cytoprotective efflux pumps that may contribute to the preservation of these cells. The aim of this study was to determine the ABC transporter phenotype of HPCs. Methods: HPC activation was studied in rats treated with 2- acetylaminofluorene (2-AAF) followed by partial hepatectomy (PHx). ABC transporter gene expression was determined by real time detection reverse transcription-polymerase chain reaction in isolated HPCs, hepatocytes, cholangiocytes, and cultured progenitor cell-like RLF ϕ 13 cells and by immunohistochemistry of total liver samples. ABC transporter efflux activity was studied in RLF ϕ 13 cells by flow cytometry. Results: 2-AAF/PHx treated animals showed increased hepatic mRNA levels of the genes encoding multidrug resistance proteins Mdr1b , Mrp1 , and Mrp3 . Immunohistochemistry demonstrated expression of Mrp1 and Mrp3 proteins in periportal progenitor cells and of the Mdr1b protein in periportal hepatocytes. Freshly isolated Thy-1 positive cells and cultured RLF ϕ 13 progenitor cells highly expressed Mrp1 and Mrp3 mRNA while the hepatocyte specific transporters Mdr2 , Bsep , Mrp2 , and Mrp6 were only minimally expressed. Blocking Mrp activity by MK-571 resulted in accumulation of the Mrp specific substrate carboxyfluorescein in RLF ϕ 13 cells. Conclusion: HPCs express high levels of active Mrp1 and Mrp3. These may have a cytoprotective role in conditions of severe hepatotoxicity.

Hepatic oval cells (HOC) are thought to be a type of facultative stem cell that arises as a result of certain forms of hepatic injury. A new and more efficient model has been established to activate the oval cell compartment in mice by incorporating 3,5-diethoxycarbonyl-1,4-dihydro-collidine (DDC) in a standard chow at a concentration of 0.1%. At the present time, very few markers exist for the mouse oval cells. One accepted marker is A6, an uncharacterized epitope recognized by mouse hepatic oval cells and it is accepted to be an oval cell marker. Sca-1 is a cell surface marker used to identify hematopoietic stem cells in conjunction with Thy-1+, CD34+, and lineage-specific markers. Both the CD34 and Sca-1 antigens are not normally expressed in adult liver, but are expressed in fetal liver, presumably on the hematopoietic cells. We report herein that mouse oval cells express high levels of Sca-1 and CD34, as well as CD45 surface proteins. Immunohistochemistry revealed that the cells expressing Sca-1/CD34/CD45 were indeed oval cells because they co-expressed the oval cell–specific marker A6 (94.57% ± 0.033%), as well as alpha-fetoprotein (AFP) (75.92% ± 0.071%). By using Sca-1 antibody in conjunction with magnetic activated cell sorting (MACS), followed with a flow cytometric cell sorting (FACS) method for CD34 and CD45, we have developed a rapid oval cell isolation protocol with high yields of greater than 90%. In conclusion, we have an efficient murine model for the production and isolation of large numbers of highly purified oval cells. Our system works with most strains of mouse, which will facilitate both in vivo and in vitro studies of mouse hepatic oval cells. (H EPATOLOGY 2003;37:632-640.)

Hepatocyte growth factor/scatter factor (HGF/SF) is a pluripotent growth factor capable of acting as a motogen, a morphogen, and a mitogen. Originally, HGF/SF was found as a blood-borne mitogen for hepatocytes and has since been determined to be very important in liver repair. Previous studies have established that HGF/SF must be proteolytically cleaved to elicit its effects. After liver injury by toxins such as carbon tetrachloride or after surgical resection, partial hepatectomy (PHX), HGF/SF concentrations increase in the blood. The aims of this study were to examine (1) which form of HGF/SF is present in the normal liver, (2) which form is present in the regenerating liver after PHX, and (3) if the HGF/SF used after PHX is derived from existing liver reservoirs. Both single-chain HGF/SF and active two-chain HGF/SF are present in normal liver, with the former being the dominant form. After PHX, the liver can be described as having two phases with regard to the use of endogenous HGF/SF. The first phase from 0 to 3 hours is the consumptive phase and is characterized by a decrease in both single-chain HGF/SF and active two-chain HGF/SF. The second phase is the productive phase. It is characterized by a pronounced reappearance of both single-chain HGF/SF as well as two-chain HGF/SF. The activation index shows a 5-fold increase over sham operations during the productive phase. The use of radiolabeled HGF/SF showed that during the first 3 hours, HGF/SF is used in part from hepatic stores. Furthermore, during the first 3 hours after PHX, only active two-chain HGF/SF is seen in the plasma.

Hepatocyte growth factor (HGF) was recently recognized as a potential neurotrophic factor in the developing brain. We studied expression of HGF and its receptor using Northern blot analysis and in situ hybridization for mRNA and double immunofluorescent laser confocal microscopy. HGF and cMet messages were abundant in the hippocampus of both human and rat brains. In this region, both messages were localized in the neuronal layer. Segregation of HGF predominantly in the hippocampal CA3-4 and cMet in CA1 supports the hypothesis that HGF may mediate important neurotrophic functions in both developing and adult brains.

Hepatocyte growth factor (HGF) is a pleiotropic growth factor which, in addition to its mitogenic potency for primary hepatocytes, also has a role in the regulation of cell motility, cell growth and morphogenesis. In the present study, we show that c-met, the high-affinity receptor for HGF, is expressed on human cord blood (CB) CD34+ progenitor cells and CD34+Thy-1+ Lin− (lin−) cells. We have investigated the capacity of HGF to synergize with other growth factors to induce colony formation by CB CD34+ progenitor cells. CD34+ cells were cultured in semisolid medium containing serum with increasing concentrations of GM-CSF, G-CSF, macrophage colony-stimulating factor (M-CSF), stem cell factor (SCF), interleukin 3 (IL-3) and IL-11 alone or in combination with HGF. HGF acted as a potent synergist and enhanced, up to fourfold, colony formation induced by GM-CSF, G-CSF or M-CSF. HGF in combination with SCF, IL-3 or IL-11 did not induce proliferation of colony forming units-granulocyte macrophage (CFU-GM) above control levels. In serum-deprived cultures, HGF was only detectably synergistic with IL-11, and all other culture combinations showed no proliferation. To determine whether the stimulatory effect of IL-11 and the synergistic effect of HGF in the absence of serum could be attributed to the effect of these two cytokines on stem cells, IL-11-stimulated and unstimulated lin− cells were analyzed for expression of c-met. CD34+Thy-1+Lin− cells were positive for c-met, both in the presence and absence of IL-11 stimulation, and Northern analysis indicated that c-met RNA expression was upregulated in response to IL-11 compared to unstimulated controls. These results provide strong evidence for upregulation of the HGF receptor on primitive hematopoietic cells by IL-11, and for the synergistic role of HGF in colony formation by hematopoietic stem cells.

This monograph examines several external and internal factors that influence innovation as they apply to military organizations in general and to the development of the American antiaircraft artillery establishment between World War I and World War II specifically. A child of World War I, the antiaircraft artillery fought against external and internal post-war pressures to emerge as an accepted member of the family of arms by 1941. The emergence of the antiaircraft artillery during this period represented a shift within its parent branch, the Coast Artillery Corps, away from the traditional mission of seacoast defense. Over the course of this shift, the antiaircraft artillery fought against not only the purveyors of the status quo in the seacoast artillery who sought to shield their organization from technical and political obsolescence, but also the other combat arms within the Army, in particular the Air Corps, which disagreed with the Coast Artillery over the need for antiaircraft artillery. For these reasons, the history of the antiaircraft artillery is an excellent vehicle through which to examine the phenomenon of military innovation. (MM)

While the Persian Gulf War confirmed the political and strategic utility of using ballistic missiles as a terror weapon, the effect of ballistic missiles on tactical operations has received much less attention. Despite growing evidence of technological advances in guidance and warhead systems that warrant concern, much of the current literature ignores the operational and tactical impact of ballistic missiles on the battlefield. Even the US Army's most forward looking document, US Army Training and Doctrine Command (TRADOC) Pamphlet 525-5, Force XXI Operations (1 August 1994), disregards the impact of these weapons on tactical operations. Thus, this monograph breaks new ground and demonstrates why military leaders and planners should pay more attention to the emerging tactical threat from ballistic missiles, unconventional warheads, and weapons of mass destruction.

TGF-beta 1 is known as a potent inhibitor of proliferation of rat and human hepatocytes. In this study we show that the effects of TGF-beta 1 are quite different on mouse hepatocytes. In rat and human hepatocytes, TGF-beta 1 inhibited DNA synthesis and also inhibited the morphological changes induced by growth factors in rat and human hepatocytes. In contrast, addition of TGF-beta 1 to mouse hepatocytes resulted in pronounced alterations in morphology of these cells. These changes were similar to those induced by HGF and EGF. The induction of structural changes by TGF-beta 1 was noted only in mouse hepatocytes. Mouse hepatocytes were also much more resistant to the mito-inhibitory effect of TGF-beta 1. These findings suggest profound differences in hepatocyte growth regulation between these species and may relate to observed differences in susceptibility to carcinogenesis.