Diagnosis of cerebral toxoplasmosis by a nested polymerase chain reaction: a case report

A 24-year-old man infected with human immunodeficiency virus type I rapidly progressed to acquired immune deficiency syndrome. His clinical picture was compatible with a presumptive diagnosis of cerebral toxoplasmosis. Application of a nested polymerase chain reaction (PCR) succeeded in detecting Toxoplasma gondii DNA in both the venous blood and cerebrospinal fluid specimens. This result indicates that PCR is a convenient tool for making a rapid and accurate diagnosis of cerebral toxoplasmosis, especially in developing countries.

Orthodontic treatment planning for inclusion of the third molar in the dental arches: Part II

Marked lower anterior crowding (late crowding or post-adolescent crowding) often develops at about the time of third molar eruption. Many studies have implicated the presence of third molars as a cause of this crowding. Despite the fact that there is no clear evidence that this is the case, many orthodontists and their patients' referring dentists routinely remove third molars at the retention stage of treatment to prevent crowding later; Ricketts et al. even advocate enucleation of the third molar while the patient is very young to prevent future crowding. In the following report on two orthodontically-treated patients (the first three cases in this report were published in The Australian Orthodontic Journal, Volume 15, Number 1), the author emphasises the importance of careful consideration of the third molar in the treatment plan.

Melanoma differentiation associated gene-9, mda-9, is a human gamma interferon responsive gene

Subtraction hybridization using a cDNA library prepared from temporally spaced mRNAs from human melanoma cells treated with recombinant human fibroblast interferon (IFN-beta) plus mezerein (MEZ) that induces terminal differentiation (tester cDNA library) and a temporally spaced cDNA library prepared from actively proliferating melanoma cells (driver cDNA library) produced a Temporally Spaced Subtracted (TSS) cDNA library. This approach resulted in the identification of melanoma differentiation associated (mda) genes displaying both enhanced and suppressed expression during growth inhibition and differentiation. In the present report, we describe a novel cDNA mda-9 that consists of 2084 nucleotides, and encodes a protein of 298 amino acids with a predicted M(r) of approx. 33 kDa. Treatment of human SV40-immortalized normal melanoma cells with immune interferon, INF-gamma, induces growth suppression and enhances mda-9 expression without inducing terminal differentiation. These results establish that induction of terminal differentiation in human melanoma cells, using the combination of a type I interferon (IFN-beta) + MEZ, can elicit signaling pathways and gene expression changes also regulated by type II immune interferon.

Mesoderm induction by heterodimeric AP-1 (c-Jun and c-Fos) and its involvement in mesoderm formation through the embryonic fibroblast growth factor/Xbra autocatalytic loop during the early development of Xenopus embryos

We have previously demonstrated the involvement of AP-1/Jun in fibroblast growth factor (FGF) signaling by loss-of-function assay (Dong, Z., Xu, R.-H., Kim, J., Zhan, S.-N., Ma, W.-Y., Colburn, N. H., and Kung, H. (1996) J. Biol. Chem. 271, 9942-9946). Further investigations by gain-of-function are reported in this study. AP-1 transactivation activity was increased by the treatment of animal cap explants with FGF. Ectopic overexpression of two components of AP-1 (c-jun and c-fos together, but not alone) produced posteriorized embryos and induced mesoderm formation in animal cap explants, indicating that both AP-1 heterodimers are required for mesoderm induction. Since Ras/AP-1 functions downstream of FGF signaling, we then tested the involvement of Ras/AP-1 in mesoderm maintenance mediated by embryonic FGF/Xbra using dominant-negative mutants. Mesoderm maintenance mediated by embryonic FGF/Xbra was blocked by dominant-negative mutants of Ras/AP-1, and AP-1 enhanced the expression of Xbra. Further studies demonstrated the inhibition of Ras/AP-1-mediated mesoderm formation by dominant-negative mutants of the FGF receptor and Xbra. These results indicate that Ras/AP-1 and FGF/Xbra signals are involved in the mesoderm maintenance machinery and mesoderm formation through the synergistic action of the diversified signal pathways derived from the FGF/Xbra autocatalytic loop.

Synthetic scleral reinforcement materials. III. Changes in surface and bulk physical properties

Changes in the physical properties of polymer materials during implantation in the biological environment can directly affect the ultimate performance of the polymer and/or device. We implanted four types of extraocular bands (porous, solid, composite, and patched) made from 11 types of materials in rabbit eyes and examined the changes in the physical strength and polymer structure of the implanted bands in terms of tensile strength measurements, creep analysis, and attenuated total internal reflectance--Fourier transform infrared spectroscopy (ATR-FTIR) at intervals up to 18 months after implantation. Most of the materials showed increases in tensile strength over the first 6 months in situ in the rabbit eye, followed by significant decreases between 6 and 18 months. Polymer bands that had been implanted for 18 months generally exhibited less creep behavior than unimplanted controls; for most of the bands, creep values ranged from 0% to 10% of the original length. ATR-FTIR of the solid bands and surface coatings showed protein deposition on all of the materials examined, with silicone materials and coatings least affected. Thirty-degree ATR-FTIR scans detected significant changes in the polymer structure for two of the band types: one solid (polyether urethane) and one porous (porous polyacrylate). In general, expanded polytetrafluoroethylene was the most stable in terms of tensile strength and creep. The least stable bands (composite bands made with porous polyurethane) were those that had undergone hydrolytic and/or oxidative degradation and chain scission of the polymer or alteration of the bond between the two materials making up the composite. These changes in physical properties and polymer structure observed after 18 months of implantation support the idea that polymer implant materials should be followed closely over several years in vivo to determine their suitability prior to use in humans.

A sampling and analytical method for the simultaneous determination of multiple organonitrogen pesticides in air

An air sampling and analytical method was developed for organonitrogen pesticides using a combined filter and XAD-2 sorbent sampler and high performance liquid chromatography-ultraviolet detection. The method was evaluated for 14 organonitrogen pesticides by National Institute for Occupational Safety and Health evaluation guidelines and procedures. Evaluation experiments addressed limits of detection and quantitation, analytical recovery, sampler capacity, sample stability, and precision and bias over a range of 12 to 240 micrograms per sample. Samples were stable when stored for up to 30 days under either ambient or refrigerated conditions. Based on the finding of this work, 10 of the 14 compounds studied (aldicarb, captan, carbaryl, carbofuran, chlorpropham, diuron, formetanate, methiocarb, oxamyl, propham) can be successfully determined simultaneously using one method with an accuracy of better than +/- 25% of the true value with 95% confidence. Two other compounds (carbendazim/benomyl, methomyl) can be measured with the same accuracy over a more limited concentration range. The remaining two compounds (propoxur, thiobencarb) may meet this criterion, but additional samples would need to be included in the data analysis. With the current data, these two compounds can be determined with an accuracy of better than +/- 27% of the true value with 95% confidence.

Comparing the effectiveness of different educational programs for patients with total knee arthroplasty

PURPOSE

To compare the effects of preadmission and postadmission educational programs for patients with total knee arthroplasty.

DESIGN

Quasiexperimental study.

SAMPLE

60 total knee arthroplasty patients.

METHODS

Subjects in the experimental group received preadmission preoperative teaching with an instruction booklet during a preoperative outpatient clinic visit. Upon admission to the hospital, they were presented with an educational video tape. The control group received only postadmission preoperative teaching with the same instruction booklet and no video. PREADMISSION AND POSTADMISSION: Preoperative anxiety level, knowledge about postoperative care, exercise performance and postoperative recovery were used as outcome measures.

FINDINGS

The research results found: 1. there was no significant difference between the two groups in reduction of preoperative anxiety score: 2. the experimental group had a significantly higher knowledge level than the control group; 3. the experimental group performed exercise more regularly and correctly than those in the control group; 4. the experimental group had greater flexion of the operative knee joint than the control group.

CONCLUSION

Preadmission teaching with a videotape program and a health manual for patients with total knee arthroplasty is recommended.

IMPLICATIONS FOR NURSING RESEARCH

More indicators such as postoperative pain and patient satisfaction can be used to investigate the effectiveness of intervention. In addition, increasing the sample size is recommended for future studies.

Xmsx-1 modifies mesodermal tissue pattern along dorsoventral axis in Xenopus laevis embryo

This study analyzes the expression and the function of Xenopus msx-1 (Xmsx-1) in embryos, in relation to the ventralizing activity of bone morphogenetic protein-4 (BMP-4). Expression of Xmsx-1 was increased in UV-treated ventralized embryos and decreased in LiCl-treated dorsalized embryos at the neurula stage (stage 14). Whole-mount in situ hybridization analysis showed that Xmsx-1 is expressed in marginal zone and animal pole areas, laterally and ventrally, but not dorsally, at mid-gastrula (stage 11) and late-gastrula (stage 13) stages. Injection of BMP-4 RNA, but not activin RNA, induced Xmsx-1 expression in the dorsal marginal zone at the early gastrula stage (stage 10+), and introduction of a dominant negative form of BMP-4 receptor RNA suppressed Xmsx-1 expression in animal cap and ventral marginal zone explants at stage 14. Thus, Xmsx-1 is a target gene specifically regulated by BMP-4 signaling. Embryos injected with Xmsx-1 RNA in dorsal blastomeres at the 4-cell stage exhibited a ventralized phenotype, with microcephaly and swollen abdomen. Histological observation and immunostaining revealed that these embryos had a large block of muscle tissue in the dorsal mesodermal area instead of notochord. On the basis of molecular marker analysis, however, the injection of Xmsx-1 RNA did not induce the expression of alpha-globin, nor reduce cardiac alpha-actin in dorsal marginal zone explants. Furthermore, a significant amount of alpha-actin was induced and alpha-globin was turned off in the ventral marginal zone explants injected with Xmsx-1. These results indicated that Xmsx-1 is a target gene of BMP-4 signaling, but possesses a distinct activity on dorsal-ventral patterning of mesodermal tissues.

Application of amplified restriction fragment length polymorphism for genetic characterization of colletotrichum pathogens of alfalfa

ABSTRACT Amplified restriction fragment length polymorphism (AFLP) was used to assess the levels of genomic variations among species and isolates of the genus Colletotrichum. Our objective was to characterize at the molecular level two alfalfa pathogens, isolates Arl-NW and 57RR, which are unusually aggressive to anthracnose-resistant alfalfa cultivars and whose taxa has been uncertain based on morphological criteria. The fingerprint patterns obtained were complex but did enable us to place these two isolates within the species C. trifolii and C. gloeosporioides, respectively. The diversity detected with AFLP among and within Colletotrichum species from alfalfa and other crops corroborated their published taxonomy based on morphology, ribosomal DNA sequence, and random amplified polymorphic DNA analyses. Similarity matrices generated with three primer pairs were highly correlated and, thus, were combined to determine the similarity among the fungal species and isolates that were analyzed. Analysis of the data generated with each of the primer pairs individually and application of either distance or parsimony methods supported the placement of these two isolates. The parsimony method of data analysis was more confirmatory in the placement of Phoma medicaginis as an out-group than the distance method, using either simple matching or Jaccard's coefficients to generate the similarity matrices. Our conclusion is that the AFLP technique will be useful for identification of individual isolates within complex genera such as Colletotrichum because of its ability to generate large numbers of polymorphisms and the consistency of polymerase chain reaction amplification.

XBMP-1B (Xtld), a Xenopus homolog of dorso-ventral polarity gene in Drosophila, modifies tissue phenotypes of ventral explants

Previously we have isolated a Xenopus cDNA homolog of bone morphogenetic protein-1 (XBMP-1A). In the present report we describe a new cDNA clone called XBMP-1B (or Xtld) from a Xenopus embryonic library. Sequence analysis indicates that these two clones share an indentical N-terminal sequence, including a region of metalloprotease domain, three copies of a repeat first found in complement proteins C1r/s and an epidermal growth factor (EGF)-like sequence. XBMP-1B protein has an additional copy of an EGF-like sequence followed by two copies of complement 1 r/s repeat in the C-terminus. The overall protein structure predicted from the XBMP-1B sequence reveals that it encodes a protein homologous to Drosophila tolloid. Three XBMP-1 transcripts (2.9, 5.2 and 6.6 kb) were detected by northern blot analysis. However, the 2.9 kb transcript hybridized specifically with XBMP-1A and the 5.2 and 6.6 kb transcripts hybridized with XBMP-1B. In Drosophila, a major function of tolloid is to augment the activity of the decapentaplegic gene product, a close relative of tumor growth factor (TGF)-beta superfamily members, BMP-2/4. Although XBMP-1 and XBMP-4 are detected in various adult tissues of Xenopus, the expression pattern of these two genes was not tightly correlated. In the embryo, the expression of XBMP-1 increased gradually from the morula to the swimming tadpole stages. Injection of XBMP-1B RNA into the ventral blastomeres at the 4-cell stage caused an elongation of the ventral marginal zone explants and converted globin-positive blood cells to mesenchymal and muscle tissues at later stages. It was shown that XBMP-1A was less active and a 1A mutant lacking the signal sequence was inactive. Further studies revealed that injection of XBMP-1B RNA into the ventral marginal zone induced up-regulation of dorsal marginal zone markers, such as goosecoid and chordin, at the gastrulation stage. These data indicate that XBMP-1 may have a role in determining dorso-ventral patterning in Xenopus, but in a different way from the dpp/tolloid system demonstrated in Drosophila.

Suppression of human ribosomal protein L23A expression during cell growth inhibition by interferon-beta

Interferons inhibit cell growth in normal and tumor-derived cells. The molecular basis of interferons antiproliferative activity remains to be defined. Using subtraction hybridization, a human melanoma differentiation associated gene, mda-20, has been identified that is down-regulated by treatment with interferon. Sequence analysis indicates that mda-20 is human ribosomal protein L23a (rp L23a). The mRNA levels of rp L23a and growth are diminished in a variety of human tumor cell lines following treatment with human fibroblast interferon, interferon-beta (IFN-beta). Expression of rp L23a is also reduced in human melanoma cells treated with human leukocyte (IFN-alpha) and immune (IFN-gamma) interferons, but not by growth inhibition resulting from serum starvation. These findings suggest that growth suppression alone is not sufficient to reduce rp L23a expression. Instead, reduced rp L23a mRNA results from biochemical changes mediated by interferons. Ectopic expression of an antisense rp L23a sequence in human HeLa cervical carcinoma cells results in a reduction in colony formation indicating a direct antiproliferative effect by inhibiting rp L23a expression. The mechanism underlying inhibition in rp L23a expression in IFN-beta-treated cells may involve antisense rp L23a RNA. These results suggest that rp L23a may be one of the target molecules involved in mediating growth inhibition by interferon.

A contact scoring matrix for qualitative prediction of change in folding of alpha-helices in globular proteins caused by a mutation

The atomic pairs in contact for atoms from pairs of amino-acid residues on pairs of helices in a protein database consisting of 48 proteins of known tertiary structure from the Brookhaven Protein Data Bank are searched and counted to construct a primary scoring system. Each score in the primary scoring system is weighted further with the possibility of occurrence of each residue pair in the protein database to give a final scoring matrix. Scores for predicting change in folding of alpha-helices in a mutant protein are calculated by assuming that every pair of helices in the protein can closely interact with each other. It is shown that the change in folding of alpha-helices in several mutant proteins are reflected in both the change of the contact scores and the helix geometry calculated.

Differential regulation of neurogenesis by the two Xenopus GATA-1 genes

Previously, we have shown that the ventralizing factor bone morphogenetic protein 4 (BMP-4) can inhibit Xenopus neurogenesis. The erythroid transcription factor GATA-1 functions downstream of the BMP-4 signaling pathway and mediates BMP-4-induced erythropoiesis. We have found that similar to BMP-4, GATA-1b inhibits neuralization of Xenopus animal cap (AC) cells. The neural inhibition is not seen with GATA-1a, although both GATA-1a and GATA-1b RNAs are translated at the same efficiency and induce globin expression equally in AC cells. GATA-1b RNA injection into AC cells neither induces expression of Xbra (a general mesoderm marker) nor affects expression of XK81 (epidermal keratin) or BMP-4 and Xvent-1 (two ventral markers). These data suggest that GATA-1b retains the epidermal fate of the AC. Intact GATA-1b protein is required for both inhibition of neurogenesis and induction of globin expression. Our findings indicate that GATA-1b can function in ectoderm to specifically regulate neural inducing mechanisms, apparently related to the expression of chordin, a neuralizing gene. Furthermore, tadpole stage embryos injected with GATA-1b are devoid of all dorsoanterior structures including neural tissue. This report provides evidence that the two transcription factors, derived from a recent genome duplication, share a common biological activity (stimulation of erythropoiesis) while also exhibiting a distinct function (inhibition of neurogenesis).

Tropomyosin localization reveals distinct populations of microfilaments in neurites and growth cones

The functional and structural differences between neurites and growth cones suggests the possibility that distinct microfilament populations may exist in each domain. Tropomyosins are integral components of the actin-based microfilament system. Using antibodies which detect three different sets of tropomyosin isoforms, we found that the vast majority of tropomyosin was found in a microfilament-enriched fraction of cultured cortical neurons, therefore enabling us to use the antisera to evaluate compositional differences in neuritic and growth cone microfilaments. An antibody which reacts with all known nonmuscle isoforms of the alpha Tms gene (Tm5NM1-4) stains both neurites and growth cones, whereas a second antibody against the isoform subset, Tm5NM1-2, reacts only with the neurite. A third antibody which reacts with the Tm5a/5b isoforms encoded by a separate gene from alpha Tms was strongly reactive with both neurites and growth cones in 16-h cultures but only with the neurite shaft in 40-h cultures. Treatment of neurons with cytochalasin B allowed neuritic Tm5NM1-2 to spread into growth cones. Removal of the drug resulted in the disappearance of Tm5NM1-2 from the growth cone, indicating that isoform segregation is an active process dependent on intact microfilaments. Treatment of 40-h cultures with nocodazole resulted in the removal of Tm5NM1-2 from the neurite whereas Tm5a/5b now spread back into the growth cone. We conclude that the organization of Tm5NM1-2 and Tm5a/5b in the neurite is at least partially dependent on microtubule integrity. These results indicate that tropomyosin isoforms Tm5NM1-2, Tm5NM3-4, and Tm5a/5b mark three distinct populations of actin filaments in neurites and growth cones. Further, the composition of microfilaments differs between neurites and growth cones and is subject to temporal regulation.

Tropomyosin isoforms in nonmuscle cells

Vertebrate nonmuscle cells, such as human and rat fibroblasts, express multiple isoforms of tropomyosin, which are generated from four different genes and a combination of alternative promoter activities and alternative splicing. The amino acid variability among these isoforms is primarily restricted to three alternatively spliced exon regions; an amino-terminal region, an internal exon, and a carboxyl-terminal exon. Recent evidence reveals that these variable exon regions encode amino acid sequences that may dictate isoform-specific functions. The differential expression of tropomyosin isoforms found in cell transformation and cell differentiation, as well as the differential localization of tropomyosin isoforms in some types of culture cells and developing neurons suggest a differential isoform function in vivo. Tropomyosin in striated muscle works together with the troponin complex to regulate muscle contraction in a Ca(2+)-dependent fashion. Both in vitro and in vivo evidence suggest that multiple isoforms of tropomyosin in nonmuscle cells may be required for regulating actin filament stability, intracellular granule movement, cell shape determination, and cytokinesis. Tropomyosin-binding proteins such as caldesmon, tropomodulin, and other unidentified proteins may be required for some of these functions. Strong evidence for the distinct functions carried out by different tropomyosin isoforms has been generated from genetic analysis of yeast and Drosophila tropomyosin mutants.

The Saccharomyces CDC13 protein is a single-strand TG1-3 telomeric DNA-binding protein in vitro that affects telomere behavior in vivo

Saccharomyces telomeres consist of approximately 300 bp of C1-3A/TG1-3 DNA. Cells lacking the activity of the essential gene CDC13 display a cell cycle arrest mediated by the DNA damage sensing, RAD9 cell cycle checkpoint, presumably because they exhibit strand-specific loss of telomeric and telomere-adjacent DNA [Garvik, B., Carson, M. & Hartwell, L. (1995) Mol. Celi. Biol. 15,6128-6138]. Cdc13p expressed in Escherichia coli or overexpressed in yeast bound specifically to single-strand TG1-3 DNA. The specificity of binding displayed by Cdc13p in vitro indicates that in vivo it could bind to both the short, constitutive single-strand TG1-3 tails thought to be present at telomeres at most times in the cell cycle as well as to the long single-strand TG1-3 tails that are intermediates in telomere replication. Genes located near yeast telomeres are transcriptionally repressed, a phenomenon known as telomere position effect. Cells overexpressing a mutant form of Cdc13p had reduced telomere position effect at high temperatures. These data suggest that Cdc13p functions by binding directly to telomeric DNA, thereby limiting its accessibility to degradation and transcription as well as masking it from factors that detect damaged DNA.

Molecular cloning and characterization of a novel mouse macrophage gene that encodes a nuclear protein comprising polyglutamine repeats and interspersing histidines

Simple tandem repeats of the trinucleotide sequence CAG encode homopolymeric stretches of glutamine. Although polyglutamine has been identified in diverse proteins, it is present predominantly in transcription factors. We observed that oncogene-immortalized mouse macrophages express several genes that contain a CAG repeat motif. Therefore, we attempted to clone a novel gene that contains a CAG repeat and is associated with cytokine activation of macrophages. Screening of a mouse macrophage cDNA library with a probe comprising 12 consecutive CAG triplets identified at least one unique clone. The cDNA encodes a protein (named GRP-1 or glutamine repeat protein-1) with 171 amino acids, a calculated molecular mass of 21.6 kDa, and a predicted pI of 10.67. Greater than two-thirds of GRP-1 are only two amino acids, namely glutamine (50%) and histidine (18%). There are four polyglutamine motifs interspersed with histidine-rich regions. There is also a putative nuclear localization signal flanked by sites for possible serine phosphorylation. GRP-1 mRNA was expressed constitutively in some macrophage cell lines and B and T cell lines. Interferon-gamma or lipopolysaccharide augmented GRP-1 mRNA expression in the mouse macrophage cell line ANA-1. Western blot analyses using an antipeptide serum revealed that GRP-1 was localized in the nucleus of ANA-1 macrophages and transfected 3T3 fibroblasts. Overexpression of GRP-1 decreased Sp1-driven chloramphenicol acetyltransferase gene expression in transient cotransfection experiments. Because polyglutamine motifs can cause protein oligomerization and can function as transcriptional activation domains, we suggest that GRP-1 may be a transcription factor associated with interferon-gamma- or lipopolysaccharide-induced activation of macrophages.

A PCR-based DNA fingerprinting technique: AFLP for molecular typing of bacteria

Amplified restriction fragment polymorphism (AFLP) is a PCR-based DNA fingerprinting technique. In AFLP analysis, bacterial genomic DNA is digested with restriction enzymes, ligated to adapters, and a subset of DNA fragments are amplified using primers containing 16 adapter defined sequences with one additional arbitrary nucleotide. Polymorphisms of different Escherichia coli strains or Agrobacterium tumefaciens strains were demonstrated as distinct, unique bands in a denaturing sequencing gel using AFLP. The polymorphisms detected between BL21 and BL21F'IQ and between DH5 alpha and DH5 alpha F'IQ strains indicated that AFLP is able to resolve differences in F' episomal DNA (approximately 100 kb).

Changes in laminin during recovery from postischemic acute renal failure in rats

Changes in the immunoreactivity of laminin have been demonstrated in a variety of tissues undergoing injury-regeneration process and during nephrogenesis. Studies in vitro revealed that laminin is important in many cellular functions such as growth, differentiation, and cell communication. This study examined the changes of laminin in the extracellular matrix (ECM) of proximal straight tubules (PST) in the outer stripe of the outer medulla after renal ischemia, an area where most morphological damage occurred. Anesthetized male Sprague-Dawley adult rats underwent a 30-min temporary occlusion of the left renal artery. The inulin clearance (Cin) of the postischemic left kidneys was significantly decreased at 30 min, 1 day, 2 days, and 5 days after the injury, and at 7 and 10 days after the injury it rose to a level not significantly different from the sham-operated controls. Using immunogold electron microscopy, the density of immunoreactive laminin (gold-conjugated laminin grains/micron2 ECM area) in PST where flattened PST cells were present was decreased at 1 day and 2 days, and at 5 days, a time when the renal function was still depressed, it returned to a level not significantly different from that in controls. These changes were not observed in those PST or proximal convoluted tubules in which morphology was intact. Further studies are needed to determine if these changes in laminin of damaged PST cells have any significant role during their recovery from the ischemic injury.

The melanoma differentiation associated gene mda-7 suppresses cancer cell growth

Cancer is a disease characterized by defects in growth control, and tumor cells often display abnormal patterns of cellular differentiation. The combination of recombinant human fibroblast interferon and the antileukemic agent mezerein corrects these abnormalities in cultured human melanoma cells resulting in irreversible growth arrest and terminal differentiation. Subtraction hybridization identifies a melanoma differentiation associated gene (mda-7) with elevated expression in growth arrested and terminally differentiated human melanoma cells. Colony formation decreases when mda-7 is transfected into human tumor cells of diverse origin and with multiple genetic defects. In contrast, the effects of mda-7 on growth and colony formation in transient transfection assays with normal cells, including human mammary epithelial, human skin fibroblast, and rat embryo fibroblast, is quantitatively less than that found with cancer cells. Tumor cells expressing elevated mda-7 display suppression in monolayer growth and anchorage independence. Infection with a recombinant type 5 adenovirus expressing antisense mda-7 eliminates mda-7 suppression of the in vitro growth and transformed phenotype. The ability of mda-7 to suppress growth in cancer cells not expressing or containing defects in both the retinoblastoma (RB) and p53 genes indicates a lack of involvement of these critical tumor suppressor elements in mediating mda-7-induced growth inhibition. The lack of protein homology of mda-7 with previously described growth suppressing genes and the differential effect of this gene on normal versus cancer cells suggests that mda-7 may represent a new class of cancer growth suppressing genes with antitumor activity.