An epidemic of enterovirus 71 infection in Taiwan. Taiwan Enterovirus Epidemic Working Group

BACKGROUND

Enteroviruses can cause outbreaks of hand-foot-and-mouth disease (characterized by vesicular lesions on the hands, feet, and oral mucosa) or herpangina, usually without life-threatening manifestations. In 1998 an epidemic of enterovirus 71 infection caused hand-foot-and-mouth disease and herpangina in thousands of people in Taiwan, some of whom died.

METHODS

We assessed the epidemiologic aspects of this outbreak. Cases of hand-foot-and-mouth disease or herpangina in ambulatory patients were reported to the Taiwan Department of Health by a mean of 818 sentinel physicians. Severe cases in hospitalized patients were reported by 40 medical centers and regional hospitals. Viruses were isolated by 10 hospital laboratories and the department of health.

RESULTS

The sentinel physicians reported 129,106 cases of hand-foot-and-mouth disease or herpangina in two waves of the epidemic, which probably represents less than 10 percent of the estimated total number of cases. There were 405 patients with severe disease, most of whom were five years old or younger; severe disease was seen in all regions of the island. Complications included encephalitis, aseptic meningitis, pulmonary edema or hemorrhage, acute flaccid paralysis, and myocarditis. Seventy-eight patients died, 71 of whom (91 percent) were five years of age or younger. Of the patients who died, 65 (83 percent) had pulmonary edema or pulmonary hemorrhage. Among patients from whom a virus was isolated, enterovirus 71 was present in 48.7 percent of outpatients with uncomplicated hand-foot-and-mouth disease or herpangina, 75 percent of hospitalized patients who survived, and 92 percent of patients who died.

CONCLUSIONS

Although several enteroviruses were circulating in Taiwan during the 1998 epidemic, enterovirus 71 infection was associated with most of the serious clinical manifestations and with nearly all the deaths. Most of those who died were young, and the majority died of pulmonary edema and pulmonary hemorrhage.

Cloning of cDNA for the major DNA-binding protein of the erythroid lineage through expression in mammalian cells

Genes expressed in erythroid cells contain binding sites for a cell-specific factor believed to be an important regulator for this haematopoietic lineage. Using high-level transient expression in mammalian cells, we have identified complementary DNA encoding the murine protein. The factor, a new member of the zinc-finger family of DNA-binding proteins, is restricted to erythroid cells at the level of RNA expression and is closely homologous between mouse and man.

p150Ship, a signal transduction molecule with inositol polyphosphate-5-phosphatase activity

The production, survival, and function of monocytes and macrophages is regulated by the macrophage colony-stimulating factor (M-CSF or CSF-1) through its tyrosine kinase receptor Fms. Binding of M-CSF to Fms induces the tyrosine phosphorylation and association of a 150-kD protein with the phosphotyrosine-binding (PTB) domain of Shc. We have cloned p150 using a modified yeast two-hybrid screen. p150 contains one SH2 domain, two potential PTB-binding sites, an ATP/GTP-binding domain, several potential SH3-binding sites, and a domain with homology to inositol polyphosphate-5-phosphatases. p150 antibodies detect this protein in FDC-P1 myeloid cells, but the same protein is not detectable in fibroblasts. The antibodies immunoprecipitate a 150-kD protein from quiescent or M-CSF-stimulated FDC-P1 cells that hydrolyzes PtdIns(3,4,5)P3, to PtdIns(3,4)P2. This activity is observed in Shc immunoprecipitates only after M-CSF stimulation. Retroviral expression of p15O in FD-Fms cells results in strong inhibition of cell growth in M-CSF and a lesser inhibition in IL-3. Ectopic expression of p150 in fibroblasts does not inhibit growth. This novel protein, p150(ship) (SH2-containing inositol phosphatase), identifies a component of a new growth factor-receptor signaling pathway in hematopoietic cells.

Functional analysis and in vivo footprinting implicate the erythroid transcription factor GATA-1 as a positive regulator of its own promoter

Transcription of erythroid-expressed genes and normal erythroid development in vivo are dependent on a regulatory protein (GATA-1) that recognizes a consensus GATA motif. GATA-1 expression is itself restricted to erythroid progenitors and to two related hematopoietic lineages, megakaryocytes and mast cells. During cellular maturation the levels of GATA-1 RNA and protein increase progressively. In an effort to delineate mechanisms by which this pivotal transcription factor is itself regulated we have characterized the mouse GATA-1 gene and cis-elements within its promoter. We find that the isolated promoter retains cell specificity exhibited by the intact gene. Full promoter activity requires the presence of proximal CACCC box sequences and an upstream, double GATA motif that binds a single GATA-1 molecule in an asymmetric fashion. Using in vivo footprinting of mouse erythroleukemic cells we detect protein binding in vivo to both cis-elements. On the basis of these findings we propose that a positive feedback loop mediated through GATA-1 serves two complementary functions: maintenance of the differentiated state by locking the promoter into an "on" state, and programming the progressive increase in protein content throughout cellular maturation.

Interaction of human thyroid hormone receptor beta with transcription factor TFIIB may mediate target gene derepression and activation by thyroid hormone

The human thyroid hormone receptor beta (hTR beta) is capable of both transcriptional silencing and hormone-dependent activation. However, the detailed mechanism of this transcriptional regulation remains to be elucidated. One possibility is that hTR beta interacts directly with factors of the basal transcriptional machinery, thereby modulating basal promoter activity in a direct manner, as has been shown for other transcription factors. Here, we show that hTR beta interacts specifically with the human basal transcription factor TFIIB. Deletion analysis revealed two contact sites in the receptor: one is located in the N terminus, while the other is part of the ligand-binding domain (LBD) and is located at the C terminus. Interestingly, each receptor contact site interacts with different sites in TFIIB. Cotransfection experiments revealed that, when fused to the DNA-binding domain of yeast transcription factor GAL4, the C-terminal interaction site of hTR beta was transcriptionally inactive; however, when it was cotransfected with the remaining part of the LBD on a separate molecule, silencing function was restored. In agreement with that, we show that thyroid hormone is able to significantly decrease the interaction of its receptor LBD with TFIIB. Our data suggest that hTR beta acts as a transcriptional silencer by interacting with TFIIB and that thyroid hormone may act in part by preventing transcriptional repression at this level.

Increased gamma-globin expression in a nondeletion HPFH mediated by an erythroid-specific DNA-binding factor

In man, a shift from gamma- to beta-globin gene expression in erythroblasts underlies a switch from fetal to adult haemoglobin during development. In hereditary persistence of fetal haemoglobin (HPFH), inappropriately high gamma-globin expression in adult life is associated with deletions in the beta-globin cluster or with single-base changes upstream of the gamma-globin genes. To account for enhanced gamma-gene expression in HPFH of the non-deletion type, we tested the nuclear proteins of human erythroleukaemia cells that bind gamma-promoter sequences in vitro by correlating specific mutations in their binding sites with promoter activity. An erythroid-specific factor (GF-1) binds as a single molecule to the -195 to -170 region and contacts two TATCT(AGATA) motifs, but not the conserved octamer (ATGCAAAT) that separates them. We observe that a single change (at -175, T----C) found in HPFH leads to increased promoter activity only in erythroid cells. This effect is mediated by GF-1, the human counterpart of the chicken erythroid factor Eryf 1. The form of HPFH we studied here is an inherited disorder which can be ascribed to the action of a cell-specific DNA-binding factor on a mutant promoter.

Cytogenetic characterization of selected small round cell tumors of childhood

Small, round, blue-cell tumors (SRCT), including rhabdomyosarcoma, Ewing's sarcoma of bone and soft tissue, mesenchymal chondrosarcoma, small cell osteosarcoma, hemangiopericytoma, neuroblastoma, peripheral neurectodermal tumor (peripheral neuroepithelioma of bone and soft tissue), and the malignant small cell tumor of the thoracopulmonary region described by Askin (Askin's tumor), are often difficult to distinguish by light microscopy. We have evaluated the cytogenetics of these tumors by studying 24 tumor explants in short-term culture and 22 tumor cell lines. In Ewing's sarcoma (a tumor of unknown histogenesis), and in peripheral neuroepithelioma and Askin's tumor (tumors with evidence of neural origin), we have observed an indistinguishable t(11;22) translocation.

Lymphohematopoietic progenitors immortalized by a retroviral vector harboring a dominant-negative retinoic acid receptor can recapitulate lymphoid, myeloid, and erythroid development

The lymphohematopoietic progenitors represent < 0.01% of nucleated marrow cells. Here, we describe the immortalization of the murine lymphohematopoietic progenitors by a retroviral vector harboring a dominant-negative retinoic acid receptor. The immortalized progenitors proliferate as a stem-cell-factor-dependent clonal line EML that spontaneously generates pre-pro-B lymphocytes and erythroid and myeloid progenitors. Upon stimulation with interleukin-7 and stromal cells, the pre-pro-B lymphocytes express RAG-1 and undergo D-J rearrangements of the immunoglobulin heavy-chain genes. With erythropoietin the erythroid progenitors proliferate and differentiate into red cells. Generation of the common progenitors for neutrophils and macrophages is suppressed in EML but is inducible by high concentrations of retinoic acid. An additional block in neutrophil differentiation occurs at the promyelocyte stage but can also be overcome by high concentrations of retinoic acid. These studies demonstrate a reproducible way to immortalize lymphohematopoietic progenitors and implicate specific roles for retinoic acid receptors at two distinct stages of hematopoiesis.

Human GATA-3: a lineage-restricted transcription factor that regulates the expression of the T cell receptor alpha gene

In addition to its role in the recognition of foreign antigens, the T cell receptor (TCR) alpha gene serves as a model system for studies of developmentally-regulated, lineage-specific gene expression in T cells. TCR alpha gene expression is restricted to cells of the TCR alpha/beta+ lineage, and is controlled by a T cell-specific transcriptional enhancer located 4.5 kb 3' to the C alpha gene segment. The TCR alpha enhancer contains four nuclear protein binding sites called T alpha 1-T alpha 4. In this report we describe the identification and characterization of a novel human cDNA, hGATA-3 that binds to the T alpha 3 element of the human TCR alpha enhancer. hGATA-3 contains a zinc finger domain that is highly related to the DNA-binding domain of the erythroid-specific transcription factor, GATA-1, and binds to a region of T alpha 3 that contains a consensus GATA binding site (AGATAG). Northern blot analyses of hematopoietic cell lines demonstrate that hGATA-3 is expressed exclusively in T cells. Overexpression of hGATA-3 in HeLa cells or human B cells specifically activated transcription from a co-transfected reporter plasmid containing two copies of the T alpha 3 binding site located upstream of the minimal SV40 promoter. Taken together these results demonstrate that hGATA-3 is a novel lineage-specific hematopoietic transcription factor that appears to play an important role in regulating the T cell-specific expression of the TCR alpha gene.

Patterns of histone variant synthesis can distinguish G0 from G1 cells

Quiescent Chinese hamster ovary cells, as well as three other types of quiescent cells, synthesize histone at a reduced but significant rate. The variant patterns of the histone synthesis in quiescent, S-phase and G1-phase and G2-phase cells ali differed from each other. H3.3 was the only H3 variant synthesized in quiescent and in G1 and G2 cells. All four H2A variants were synthesized in quiescent and S-phase cells, but only H2A.X and H2A.Z were synthesized in G1 and G2 cells. No part of G1 or the G1-S transition could be found with an H2A synthesis pattern like that in quiescent cells. These findings suggest that the quiescent state is not part of G1, but that it is a separate and discrete state.

Oncoprotein TLS interacts with serine-arginine proteins involved in RNA splicing

The gene encoding the human TLS protein, also termed FUS, is located at the site of chromosomal translocations in human leukemias and sarcomas where it forms a chimeric fusion gene with one of several different genes. To identify interacting partners of TLS, we screened a yeast two-hybrid cDNA library constructed from mouse hematopoietic cells using the C-terminal region of TLS in the bait plasmid. Two cDNAs encoding members of the serine-arginine (SR) family of proteins were isolated. The first SR protein is the mouse homolog of human splicing factor SC35, and the second SR member is a novel 183-amino acid protein that we term TASR (TLS-associated serine-arginine protein). cDNA cloning of human TASR indicated that mouse and human TASR have identical amino acid sequences. The interactions between TLS and these two SR proteins were confirmed by co-transfection and immunoprecipitation studies. In vivo splicing assays indicated that SC35 and TASR influence splice site selection of adenovirus E1A pre-mRNA. TLS may recruit SR splicing factors to specific target genes through interaction with its C-terminal region, and chromosomal translocations that truncate the C-terminal region of TLS may prevent this interaction. Thus TLS translocations may alter RNA processing and play a role in malignant transformation.

A dominant negative retinoic acid receptor blocks neutrophil differentiation at the promyelocyte stage

We have investigated the roles of retinoic acid receptors in the development of neutrophils by using an interleukin 3-dependent multipotent hematopoietic cell line (FDCP mix A4) as well as normal mouse bone marrow cells. Treatment of the FDCP mix A4 cells with murine granulocyte/macrophage-colony-stimulating factor (GM-CSF) induced these cells to differentiate into neutrophils and macrophages. When the endogenous retinoic acid receptor activity in FDCP mix A4 cells was suppressed by a dominant negative retinoic acid receptor construct, this GM-CSF-induced neutrophil differentiation was blocked at the promyelocyte stage. The blocked promyelocytes proliferated continuously as a GM-CSF-dependent cell line but could be induced to terminally differentiate into neutrophils with supraphysiological concentrations of all-trans-retinoic acid (1-10 microM). The ability of the dominant negative retinoic acid receptor to block neutrophil differentiation at the promyelocyte stage was also demonstrated in normal, primary mouse bone marrow cells. Our results indicate that retinoic acid receptors in conjunction with hematopoietic growth factors play a crucial role in the terminal differentiation of normal neutrophil precursors. The system described here may also serve as a model for studying the pathogenesis of human acute promyelocytic leukemia.

Chromosomal changes and clonality relationship between primary and recurrent hepatocellular carcinoma

BACKGROUND & AIMS

Hepatocellular carcinoma (HCC) is highly malignant and prone to recur after surgical treatment. Differentiation between a true relapse of HCC and a second primary tumor is of clinical importance. However, no convenient method is currently available.

METHODS

Comparative genomic hybridization (CGH) was used to analyze 31 pairs of initial and recurrent HCC samples obtained from patients undergoing 2 consecutive surgeries. The resulting chromosomal aberration profiles were used as genomic fingerprints to determine tumor clonalities and their relationships.

RESULTS

Eleven recurrent tumors with high clonal relationship (CR) values (>0.95) were found to be relapsed HCCs, and 11 tumors with CR values close to 0 were found to be second primary HCCs. The other 9 paired samples had inconclusive CR values between 0.95 and 0.4. Two were confirmed by hepatitis B virus integration and X chromosome inactivation analysis to be de novo cancers (CR values, 0.35 and 0. 23, respectively). Initial HCCs that subsequently relapsed accumulated more chromosomal aberration events than those that developed de novo HCC (mean, 16.1 +/- 4.5 vs. 5.4 +/- 4.8 events; P < 0.01). Also, they more frequently showed gains on chromosome arms 3q, 6p, 8q, and 17q and losses on 4q and 16p.

CONCLUSIONS

CGH is useful for chromosomal aberration study and tumor clonality analysis. More and characteristic genomic changes in the initial HCC suggest that subsequent tumor recurrence is a true relapse.

Interleukin 1 induces cultured human endothelial cell production of granulocyte-macrophage colony-stimulating factor

Monokine-stimulated endothelial cells are known to produce both burst- and colony-stimulating activities, but neither the nature of the monokine nor the hematopoietic growth factor(s) produced is known. We show by mRNA analysis that an immortalized line of human endothelial cells constitutively produce granulocyte-macrophage colony-stimulating factor. Furthermore, interleukin 1 and tumor necrosis factor induce early passage human umbilical endothelial cells to produce the same growth factor.

Mycoplasmas and oncogenesis: persistent infection and multistage malignant transformation

Oncogenic potential of human mycoplasmas was studied using cultured mouse embryo cells, C3H/10T1/2 (C3H). Mycoplasma fermentans and Mycoplasma penetrans, mycoplasmas found in unusually high frequencies among patients with AIDS, were examined. Instead of acute transformation, a multistage process in promotion and progression of malignant cell transformation with long latency was noted; after 6 passages (1 wk per passage) of persistent infection with M. fermentans, C3H cells exhibited phenotypic changes with malignant characteristics that became progressively more prominent with further prolonged infection. Up to at least the 11th passage, all malignant changes were reversible if mycoplasmas were eradicated by antibiotic treatment. Further persistent infection with the mycoplasmas until 18 passages resulted in an irreversible form of transformation that included the ability to form tumors in animals and high soft agar cloning efficiency. Whereas chromosomal loss and translocational changes in C3H cells infected by either mycoplasma during the reversible stage were not prominent, the onset of the irreversible phase of transformation coincided with such karyotypic alteration. Genetic instability--i.e., prominent chromosomal alteration of permanently transformed cells--was most likely caused by mutation of a gene(s) responsible for fidelity of DNA replication or repair. Once induced, chromosomal alterations continued to accumulate both in cultured cells and in animals without the continued presence of the transforming microbes. Mycoplasma-mediated multistage oncogenesis exhibited here shares many characteristics found in the development of human cancer.

A mutated retinoic acid receptor-alpha exhibiting dominant-negative activity alters the lineage development of a multipotent hematopoietic cell line

The retinoic acid receptor (RAR alpha) is expressed in virtually all hematopoietic lineages, but the role of this transcription factor in regulating the growth and differentiation of hematopoietic progenitors is unknown. We have constructed a mutant RAR alpha that both exhibits dominant-negative activity against the normal RAR alpha in transient expression assays in mouse fibroblasts and inhibits retinoic acid-induced neutrophilic differentiation of the HL-60 human promyelocytic leukemia cell line. When this dominant-negative RAR alpha construct is introduced into the multipotent interleukin-3-dependent FDCP mix A4 murine hematopoietic cell line, there is a rapid switch from spontaneous neutrophil/monocyte differentiation to basophil/mast cell development. Thus, in this multipotent hemopoietic cell line the normal RAR alpha transcription factor and/or related molecules appear to promote the differentiation of neutrophils and monocytes but suppress the development of basophils/mast cells.

The major human erythroid DNA-binding protein (GF-1): primary sequence and localization of the gene to the X chromosome

Genes expressed in erythroid cells contain binding sites for a cell-specific nuclear factor, GF-1 (NF-E1, Eryf 1), believed to be an important transcriptional regulator. Previously we characterized murine GF-1 as a 413-amino acid polypeptide containing two cysteine-cysteine regions reminiscent of zinc-finger DNA-binding domains. By cross-hybridization to the finger domain of murine GF-1 we have isolated cDNA encoding the human homolog. Peptide sequencing of purified human GF-1 confirmed the authenticity of the human cDNA. The predicted primary sequence of human GF-1 is highly similar to that of murine GF-1, particularly in the DNA-binding region. Although the DNA-binding domains of human, murine, and chicken proteins are remarkably conserved, the mammalian polypeptides are strikingly divergent from the avian counterpart in other regions, most likely those responsible for transcriptional activation. By hybridization to panels of human-rodent DNAs we have assigned the human GF-1 locus to Xp21-11. The localization of the gene to the X chromosome has important implications for hereditary persistence of fetal hemoglobin syndromes unlinked to the beta-globin cluster and for genetic experiments designed to test the role of the factor in erythroid cell gene expression.

Enhancement of HIV-1 cytocidal effects in CD4+ lymphocytes by the AIDS-associated mycoplasma

Coinfection with Mycoplasma fermentans (incognitus strain) enhances the ability of human immunodeficiency virus type-1 (HIV-1) to induce cytopathic effects on human T lymphocytes in vitro. Syncytium formation of HIV-infected T cells was essentially eliminated in the presence of M. fermentans (incognitus strain), despite prominent cell death. However, replication and production of HIV-1 particles continued during the coinfection. Furthermore, the supernatant from cultures coinfected with HIV-1 and the mycoplasma contained a factor that inhibited the standard reverse transcriptase enzyme assay. The modification of the biological properties of HIV-1 by coinfection with mycoplasma may be involved in the pathogenesis of acquired immunodeficiency syndrome (AIDS).

Development of gene-switch transgenic mice that inducibly express transforming growth factor beta1 in the epidermis

Previous attempts to establish transgenic mouse models to study the functions of transforming growth factor beta1 (TGFbeta1) in the skin revealed controversial roles for TGFbeta1 in epidermal growth (inhibition vs. stimulation) and resulted in neonatal lethality in one instance. To establish a viable transgenic model for studying functions of TGFbeta1 in the skin, we have now developed transgenic mice, which allow focal induction of the TGFbeta1 transgene in the epidermis at different expression levels and at different developmental stages. This system, termed "gene-switch," consists of two transgenic lines. The mouse loricrin vector targets the GLVPc transactivator (a fusion molecule of the truncated progesterone receptor and the GAL4 DNA binding domain), and a thymidine kinase promoter drives the TGFbeta1 target gene with GAL4 binding sites upstream of the promoter. These two transgenic lines were mated to generate bigenic mice, and TGFbeta1 transgene expression was controlled by topical application of an antiprogestin. On epidermal-specific induction of the TGFbeta1 transgene, the BrdUrd labeling index in the transgenic epidermis decreased 6-fold compared with controls. Induction of the TGFbeta1 transgene expression also caused epidermal resistance to phorbol 12-myristate 13-acetate-induced hyperplasia, with a reduction in both epidermal thickness and BrdUrd labeling compared with those in controls. In addition, TGFbeta1 transgene expression induced an increase in angiogenesis in the dermis. Given that the TGFbeta1 transgene can affect both the epidermis and dermis, this transgenic model will provide a useful tool for studying roles of TGFbeta1 in wound-healing and skin carcinogenesis in the future.

The ets family member Tel binds to the Fli-1 oncoprotein and inhibits its transcriptional activity

The tel gene, recently shown to be translocated in a spectrum of acute and chronic human leukemias, belongs to the ets family of sequence-specific transcription factors. To determine the role of Tel in normal hematopoietic development, we used the tel gene as the bait in the yeast two-hybrid system to screen a hematopoietic stem cell library. Two partners were identified: Tel binds to itself, and Tel binds to the ets family member Fli-1. In vitro and in vivo assays confirmed these interactions. In transient transfection assays, Fli-1 transactivates megakaryocytic specific promoters, and Tel inhibits this effect of Fli-1. Transactivation studies using deletion mutants of Tel, and the Tel-AML-1 fusion protein, indicate that the helix-loop-helix domain of Tel only partially inhibits transactivation and that complete inhibition requires the full-length Tel molecule, including the DNA binding domain. The Tel and Fli-1 proteins are expressed early in hematopoiesis, and the inability of Tel fusion proteins such as Tel-AML-1 to counteract Fli-1 mediated transactivation may contribute to the malignant phenotype in human leukemias where this fusion protein is present.

Temperature-induced variations in the surface topology of cultured lymphocytes are revealed by scanning electron microscopy

Temperature-induced variations in the surface morphology of cultured lymphocytes were evaluated by scanning electron microscopy. At 25-37 degrees the cells' surfaces are largely obscured by numerous undulating microvilli of various lengths but uniform diameter. Temperature changes alter the number of microvilli, their lengths, diameters, distribution, branching, and fusing. Typically, chilling to 0-4 degrees markedly reduces the number of microvilli and increases the diameter of the survivors in a reversible process. In contrast, heating the cells to about 45 degrees rapidly and irreversibly transforms the ordinarily smooth membrane surface into one with a "cobblestone" morphology. At the same time most microvilli disappear and the few that remain clump into a cap. The data suggest that the low-temperature effects reflect a change in the physical state of membrane lipids, while the high-temperature alterations represent thermotropic protein transitions.

Alcohol and aldehyde dehydrogenases in human esophagus: comparison with the stomach enzyme activities

Alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) isoenzymes from surgical esophageal and gastric mucosa were compared by agarose isoelectric focusing. Two prominent ADH forms, designated mu 1 (equivalent to the recently reported mu-form) and mu 2, were expressed in all the 15 esophagus specimens studied, whereas only four of seven examined gastric specimens exhibited a weak to moderately strong mu 1-ADH activity band on the isoelectric focusing gels. pI values of the esophageal mu 1-ADH and mu 2-ADH, and the liver pi-ADH were determined to be 8.61, 8.13, and 8.90, respectively. mu-ADHs exhibited high Km for ethanol (12 mM) and low sensitivity to 4-methylpyrazole inhibition. ALDH3 (BB form) and ALDH1 were the major high- and low-Km aldehyde dehydrogenase in the esophagus, respectively. The ADH and ALDH activities were determined at pH 7.5 to be 751 +/- 78 and 29.9 +/- 3.0 nmol/min/g tissue, respectively (measured at 500 mM ethanol or at 200 microM acetaldehyde; mean +/- SEM; N = 15). The esophageal ADH activity was approximately 4-fold and the ALDH activity 20% that of the stomach enzyme. Because the presence of high activity and high Km mu-ADHs as well as low-activity ALDH1 were found in human esophageal mucosa, it is suggested that there may exist an accumulation of intracellular acetaldehyde during alcohol ingestion. This reactive and toxic metabolite may be involved in the pathogenesis of alcohol-induced esophageal disorders.

Mycoplasmal infections prevent apoptosis and induce malignant transformation of interleukin-3-dependent 32D hematopoietic cells

32D cells, a murine myeloid cell line, rapidly undergo apoptosis upon withdrawal of interleukin-3 (IL-3) supplement in culture. We found that 32D cells, if infected by several species of human mycoplasmas that rapidly activated NF-kappaB, would live and continue to grow in IL-3-depleted culture. Mycoplasma-infected cells showed no evidence of autocrine production of IL-3. Pyrrolidine dithiocarbamate (PDTC) blocked activation of NF-kappaB and led to prominent cell death. Heat-killed mycoplasmas or mycoplasmal membrane preparations alone could support continued growth of 32D cells in culture without IL-3 supplement for a substantial period of time. However, upon removal of heat-inactivated mycoplasmas, 32D cells quickly became apoptotic. In comparison, live Mycoplasma fermentans or M. penetrans infection for 4 to 5 weeks induced malignant transformation of 32D cells. Transformed 32D cells grew autonomously and no longer required support of growth-stimulating factors including IL-3 and mycoplasmas. The transformed 32D cells quickly formed tumors when injected into nude mice. Karyotyping showed that development of chromosomal changes and trisomy 19 was often associated with malignant transformation and tumorigenicity of 32D cells. Mycoplasmal infections apparently affected the fidelity of genomic transmission in cell division as well as checkpoints coordinating the progression of cell cycle events.