Filgrastim treatment of three patients with clozapine-induced agranulocytosis

BACKGROUND

Agranulocytosis is the most serious side effect of clozapine therapy, occurring in approximately 1% of all treated patients. Despite careful blood monitoring, a significant number of cases of agranulocytosis and resulting fatalities have occurred. Strategies are needed to manage clozapine-induced agranulocytosis more safely.

METHOD

This report describes the management of three state hospital inpatients who developed clozapine-induced agranulocytosis. All patients were diagnosed as having chronic paranoid schizophrenia according to DSM-III-R criteria and had previously failed to respond to treatment with standard antipsychotic medications. After onset of agranulocytosis, all patients were transferred to a medical service in a university hospital and treated with recombinant granulocyte colony-stimulating factor (filgrastim).

RESULTS

White blood count and absolute neutrophil count returned to within normal limits in each patient after 5 to 8 days of treatment with filgrastim 300 micrograms/day subcutaneously. No side effects were observed during filgrastim treatment.

CONCLUSION

Treatment with filgrastim appears to be safe and effective in decreasing the duration of clozapine-induced agranulocytosis. While further studies are necessary to establish the safety and effectiveness of this treatment, filgrastim should presently be considered a treatment of choice for clozapine-induced agranulocytosis.

[Diagnosis of Lyme borreliosis]

Lyme borreliosis is an infectious disease, caused by the spirochaete Borrelia burgdorferi and transmitted by ticks, in our regions by the tick Ixodes ricinus. The disease mainly affects skin, nervous system, joints and heart. Lyme borreliosis develops in three stages, and the various clinical manifestations may assigned to the respective stages. As far as skin is concerned, in stage I typically appears erythema chronicum migrans, very often accompanied by flu-like symptoms; in stage III, months to years after the manifestations of the early phase, acrodermatitis chronica atrophicans, may be encountered. Among the neurological manifestations, in stage II, meningoradiculoneuritis (Bannwarth's syndrome) develops as the most frequent disease, characterized by pheripheral paresis at the lower extremities and bilateral facial nerve palsy. Lyme arthritis mainly affects the knee. To assure the diagnosis of Lyme borreliosis, a number of serological tests is performed as the direct detection of the causative agent is rather difficult and time consuming. Possibly, the use of the polymerase chain reaction to detect B. burgdorferi DNA may improve the diagnostic tools.

Induction of HPRT- mutants in Chinese hamster V79 cells after heavy ion exposure

The induction of resistance to 6-thioguanine by heavy ion exposure was investigated with various accelerated ions (oxygen-uranium) up to linear energy transfer (LET) values of about 15,000 keV/microns. Survival curves are exponential with fluence; mutation induction shows a linear dependence. Cross-sections (sigma i: inactivation, sigma m: mutation) were derived from the respective slopes. Generally, sigma i rises over the whole LET range, but separates into different declining curves for single ions with LET values above 200 keV/microns. Similar behaviour is seen for sigma m. The new SIS facility at GSI, Darmstadt, makes it possible to study the effects of ions with the same LET but very different energies and track structures. Experiments using nickel and oxygen ions (up to 400 MeV/u) showed that inactivation cross-sections do not depend very much on track structure, i.e. similar values are found with different ions at the same LET. This is not the case for mutation induction, where very energetic ions display considerably smaller induction cross-sections, compared with low-energy ions of identical LET. Preliminary analyses using the polymerase chain reaction (PCR) demonstrate that even heavy ions cause "small alterations" (small deletions or base changes). The proportion of the total deletions seems to increase with LET.

Killing and mutation of Chinese hamster V79 cells exposed to accelerated oxygen and neon ions

Mutation induction by accelerated heavy ions to 6-thioguanine resistance (HPRT system) in Chinese hamster V79 cells was investigated using oxygen and neon ions with energies between 1.9 and 400 MeV/mu, corresponding to LET values between 18 and 754 keV/microns, respectively. Because of technical limitations most experiments could be performed only once. Inactivation and mutation induction cross sections, sigma i and sigma m, were obtained from the slopes of the exponential survival and the linear mutation induction curves, respectively. Both parameters increased with LET up to about 200 keV/microns, where the curves separated for the two types of ions. Calculated RBEs were higher for mutation induction than for killing for all LET values.

Drug-induced apoptosis is not necessarily dependent on macromolecular synthesis or proliferation in the p53-negative human prostate cancer cell line PC-3

The propensity of a cell to undergo apoptosis has been proposed to be a determinant for chemotherapy sensitivity that is not directly dependent on specific drug-target interactions. Androgen-independent prostate cancer is typically refractory to cytotoxic drugs, and we tested whether this is due to a loss of the ability to undergo apoptosis. Exposure of the hormone-insensitive and p53-negative human prostate carcinoma cell line PC-3 to 22 microM cisplatin, 1 microM camptothecin, 10 microM tenoposide, 135 nM vincristine, or 10 microM lovastatin for 72 h caused cell death, internucleosomal DNA fragmentation, and morphological changes typical for apoptosis. One microM cycloheximide prevented anticancer drug-induced apoptosis, whereas high concentration (1 mM) of cycloheximide alone induced apoptosis, indicating that protein synthesis was not needed for these cells to undergo apoptosis. Since cycloheximide affected DNA synthesis and proliferation of PC-3 cells, we tested whether the DNA polymerase inhibitor aphidicolin could also suppress drug-induced apoptosis. In contrast to cycloheximide, aphidicolin inhibited only vincristine-induced apoptosis. Cycloheximide prevented drug-induced changes in cell cycle distribution except for vincristine, while aphidicolin led to an accumulation of cells at the G1-S border independent of the drug used. These data indicate that macromolecular synthesis, active cell cycling, and p53 expression are not required for apoptosis to proceed in this system.

Two formats of enzyme immunoassay for the detection of saxitoxin and other paralytic shellfish poisoning toxins

A competitive direct enzyme-linked immunofiltration assay for the detection of saxitoxin was developed, using polyclonal antibodies against saxitoxin and a saxitoxin-horseradish peroxidase conjugate. The test was performed in an eight-well plastic test device, in which antibody-coated nylon membranes were pressed tightly to an absorbent cellulose layer. Saxitoxin standard or sample extract solution, saxitoxin-conjugate, and enzyme substrate/chromogen solution were sequentially added on to the membrane. The test was evaluated visually by comparing the intensity of the resulting coloured (blue) dot with that of a negative control. The detection limits for saxitoxin in buffer solution and in shellfish tissue were 4 ng/ml and 80 ng/g respectively, with an assay time of less than 15 min. Under the conditions of the immunofiltration assay, decarbamoyl-saxitoxin, gonyautoxin 2/3, and neosaxitoxin standards (in buffer) gave a positive response at concentrations of about 10 ng/ml, 40 ng/ml, and 80 ng/ml, respectively. The relative cross-reactivity of the antibody to these PSPs was similar when determined using both direct and indirect (using a saxitoxin-bovine serum albumin conjugate) competitive enzyme immunoassays in microtitre plate format. In competitive direct microtitre plate assays, the 50% binding values found for saxitoxin, decarbamoyl-saxitoxin, gonyautoxin 2/3 and neosaxitoxin were 15 pg/ml, 47.5 pg/ml, 163.5 pg/ml, and 510 pg/ml respectively. In competitive indirect microtitre assay, the respective values were 138 pg/ml, 404 pg/ml, 1582 pg/ml, and 6982 pg/ml.

Multimycotoxin dipstick enzyme immunoassay applied to wheat

A membrane-based visual dipstick enzyme immunoassay for the simultaneous detection of up to five mycotoxins was developed. Multiple dots of the respective antibodies against aflatoxin B1 (AFB1), T-2 toxin (T-2), 3-acetyldeoxynivalenol (3-AcDON), roridin A (RA), and zearalenone (ZEA) were applied onto a dipstick membrane. The competitive immunoreactions were performed by incubation of the dipstick in a test tube containing sample solution and a mixture of the respective toxin-horseradish peroxidase conjugates. After a second incubation in enzyme substrate/chromogen solution, a complete suppression of the (blue) colour development of the respective dot was scored positive. Visual detection limits for AFB1, T-2, 3-AcDON, RA, and ZEA in buffer solution were 2 ng/ml, 5 ng/ml, 50 ng/ml, 30 ng/ml, and 5 ng/ml respectively. Using a simple extraction procedure, the detection limits of the multimycotoxin assay in artificially contaminated wheat samples were 30 ng/g, 100 ng/g, 600 ng/g, 500 ng/g, and 60 ng/g, respectively.

Ca2+/Mg(2+)-dependent endonuclease activation is an early event in VP-16-induced apoptosis of human breast cancer MCF7 cells in vitro

Apoptosis is now recognized as one of the major processes regulating the size of cell populations. However, despite intensive investigations the biochemical and enzymological mechanisms involved in apoptosis remain unclear. In the present study we demonstrate activation of a Ca2+/Mg(2+)-dependent endonuclease during VP-16-induced apoptosis in MCF7 cells. Nuclease activation occurred prior to the appearance of internucleosomal DNA fragmentation, suggesting that this activation may be an early and possibly critical step in drug-induced apoptosis. Analysis of the internucleosomal DNA fragments showed that they contained phosphorylated 5'-ends, indicating that they were produced by a Ca2+/Mg(2+)-dependent endonuclease.

Murine hematopoietic progenitor cells produce IL-6 in response to IgE

Similarly to interleukin-3 (IL-3), IgE is capable of inducing IL-6 production by murine bone marrow cells (BMC). IgE responder cells do not belong to the mature bone marrow compartment but coenrich with hematopoietic progenitors in the low-density fraction of a discontinuous Ficoll gradient. A significant enhancement of IL-6 production is observed after a 4-hour stimulation, reaching a maximum between 24 and 48 hours and is preceded by increased mRNA expression. The effect of IgE on IL-6 production is not mediated by IL-3 since it is not modified by anti-IL-3 antibodies. Upon a 4-hour exposure to IgE or IL-3, a similar percentage of progenitor-enriched BMC expresses IL-6 mRNA (3.9 and 5.4%, respectively, as determined by in situ hybridization), which is not further increased by a combination of both stimuli. IgE and IL-3 responder cells also cannot be distinguished on the basis of size, internal structure, and rhodamine (Rh) retention. The BMC sorted in the most fluorescent Rhbright subset (approximately 0.2% of total BMC) produce 30- to 40-fold more IL-6 than unfractionated cells and are similarly enriched for CFU-cells (CFU-C). The most primitive cells concentrated in the Rhdull fraction do not express this biological activity. The sorted Rhbright population does not contain mature mast cells/basophils or monocytes, and IL-6 is not produced in response to Fc epsilon RI cross-linkage after presensitization with IgE.

Buthionine sulphoximine-mediated sensitisation of etoposide-resistant human breast cancer MCF7 cells overexpressing the multidrug resistance-associated protein involves increased drug accumulation

Preincubation of etoposide-resistant human MCF7 breast cancer cells (MCF7/VP) with buthionine sulphoximine (BSO) resulted in their sensitisation to etoposide and vincristine. Chemosensitisation was accompanied by elevated intracellular drug levels. In contrast, simultaneous exposure to BSO did not result in increased drug accumulation. Similar, but quantitatively smaller, effects were also observed when sensitive wild-type MCF7/WT cells were treated with BSO. In agreement with its effect on drug accumulation, BSO pretreatment also increased VP-16-stimulated cleavable complex formation between DNA topoisomerase II and cellular DNA. BSO treatment also led to a significant increase in acid-precipitable VP-16 levels in MCF7/VP, but not MCF7/WT cells. In contrast, no clear effects of BSO on drug efflux were observed and drug retention was only minimally increased after BSO treatment of both MCF7/WT and MCF7/VP cells and no difference between the two cell lines was detected. Thus, chemosensitisation by BSO appeared to be mediated through increased intracellular drug concentrations and/or protein binding.

Health and functioning among the elderly of Marin County, California: a glimpse of the future

BACKGROUND

The purpose of this study was to obtain information concerning the health status of the theoretically advantaged elderly population of Marin County, California, and to compare these data with those from other populations with different levels of socioeconomic status.

METHODS

An age-stratified sample of 2,018 community-dwelling elderly residents of Marin was selected, and these participants were interviewed between 1989 and 1991. Interview items included medical history of life-threatening diseases and chronic conditions, reported and observed disabilities, and life-style characteristics.

RESULTS

While the residents of Marin had lower mortality rates than the total U.S. population, there were few meaningful differences in measures of health and function in comparison to other elderly populations with substantially lower levels of socioeconomic status. The main exceptions were better memory performance and lower depressive symptomatology in Marin. Because of the many methodological differences, these comparisons must be viewed with caution.

CONCLUSION

The general pattern of findings in this study indicates that while death has been postponed in this socioeconomically advantaged population, the prevalence of disease and disability has not. If true, this implies that residents of an affluent community can spend a longer rather than shorter period of their late life in a state of infirmity and in need of medical care. This appears to be especially true for women.

Optical Properties of the South Pole Ice at Depths Between 0.8 and 1 Kilometer

The optical properties of the ice at the geographical South Pole have been investigated at depths between 0.8 and 1 kilometer. The absorption and scattering lengths of visible light ( approximately 515 nanometers) have been measured in situ with the use of the laser calibration setup of the Antarctic Muon and Neutrino Detector Array (AMANDA) neutrino detector. The ice is intrinsically extremely transparent. The measured absorption length is 59 +/- 3 meters, comparable with the quality of the ultrapure water used in the Irvine-Michigan-Brookhaven and Kamiokande proton-decay and neutrino experiments and more than twice as long as the best value reported for laboratory ice. Because of a residual density of air bubbles at these depths, the trajectories of photons in the medium are randomized. If the bubbles are assumed to be smooth and spherical, the average distance between collisions at a depth of 1 kilometer is about 25 centimeters. The measured inverse scattering length on bubbles decreases linearly with increasing depth in the volume of ice investigated.

Wild type p53 stimulates expression from the human multidrug resistance promoter in a p53-negative cell line

The effect of human wild type and mutant p53 proteins on the human multidrug resistance (MDR1) promoter was studied in a p53-negative human cell line. Transient expression of MDR1 promoter-chloramphenicol acetyltransferase reporter gene constructs (MDRCAT) cotransfected with p53 expression vectors was analyzed in H358 lung carcinoma cells. Cotransfection with a wild type p53 expression vector stimulated MDRCAT activity, while cotransfection with mutant p53 expression vectors altered at amino acid positions 181, 252, 258, or 273 failed to stimulate expression. Wild type p53 stimulation of MDRCAT activity was time dependent with maximal expression occurring 24-30 h following transfection and correlating with high p53 protein levels. MDR1 promoter deletion analysis suggested that the sequences involved in wild type p53 stimulation of MDRCAT activity were contained within the region from -39 to +53 relative to the start of transcription at +1. This region contains no TATA or p53 consensus binding sequence but does contain an initiator sequence. Wild type p53 stimulation of MDRCAT expression also occurred in parental and doxorubicin-resistant SW620 colon and parental 2780 ovarian cancer cell lines, indicating that wild type p53-mediated simulation of the MDR1 promoter is not restricted to a single cell line.

[Endovascular and open reconstructive treatment of arterial occlusive disease of the lower extremity in the critical ischemia stage]

Arterial revascularization is mandatory in the vast majority of patients with critical ischemia in the leg. Open surgical and percutaneous catheter procedures (angioplasty, local thrombolysis, clot extraction) can each be applied alone or in combination to avoid major amputation. Given the low invasiveness and morbidity of percutaneous techniques, they should be the method of first choice, provided suitable occlusion morphology is available. If catheter therapy is not successful, surgery can be performed. Five-year patency after surgery for femoropopliteal obstructions is approximately 60% and 40% after catheter therapy. Iliac revascularization shows higher patency rates for both procedures. Percutaneous catheter techniques can be an alterative to vascular surgery, but more importantly both can be used as complementary procedures in the same patient, provided there ist good cooperation between the vascular surgeon and the person during the interventional angiology.

Functional purification of a bacterial ATP-binding cassette transporter protein (MalK) from the cytoplasmic fraction of an overproducing strain

The malK gene of Salmonella typhimurium encoding the ATP-hydrolyzing subunit of the ATP-Binding Cassette (ABC) transporter for maltose was subcloned into the pRSET5d expression vector. Subsequently, the resulting plasmid (pES67) was introduced into Escherichia coli strain BL21(DE3)/pLysS. When strain BL21-(DE3)/pLysS/pES67 was grown at 30 degrees C in a tryptone-phosphate medium (J.T. Moore, A. Uppal, F. Maley, and G. F. Maley, Protein Expression Purif. 4, 160-163, 1993), the addition of isopropyl beta-thiogalactoside resulted in the synthesis of large amounts of MalK protein. After cell disrupture about 60% of MalK was recovered with the soluble (cytoplasmic) fraction. The protein was purified by ion exchange chromatography and dye ligand affinity chromatography. The purified MalK protein displayed enzymatic properties similar to those of a preparation purified and renatured from inclusion bodies (S. Morbach, S. Tebbe, and E. Schneider, J. Biol. Chem. 268, 18617-18621, 1993). Thus, our results disprove the view that the biochemical properties of a protein renatured from inclusion bodies might be artefactual. In addition, we provide further evidence that the modification of growth conditions and the use of a T7 expression system can be a useful approach to overcome at least in part the formation of inclusion bodies.

[Which patients in psychosomatic rehabilitation can be reached by psychotherapy?]

This report presents a cross-sectional study of the patients in a psychosomatic clinic (n = 112). Possible predictors concerning psychotherapeutic cooperation of patients are presented and discussed. Negative predictors found were: The presence of two or more strictly somatic rehabilitation treatments in the past; a therapist rating of "not capable of being motivated for psychotherapy"; a pension application, or a degree of disability of 50 ("severely disabled person" status). A positive predictor for psychotherapy is a patient's previous experience with psychosomatic therapies. Some consequences are discussed concerning indication as well as client information, preparation of clients prior to clinical treatment, and cooperation with other institutions providing psychosocial services.

Relationships between proto-oncogene expression and apoptosis induced by anticancer drugs in human prostate tumor cells

A variant of human prostate PC3 cells, isolated from PC3 cells, was shown to be significantly resistant (> 10-fold) to several clinically active anticancer drugs, including VP-16 and cisplatin. Previous studies showed that resistance to these drugs was not due to expression of the mdr1 gene, or modifications in topoisomerases but may have resulted from high expressions of certain proto-oncogenes (Yamazaki et al. (1994) Biochim. Biophys. Acta 1226, 89-96). Flow cytometry, DNA gel electrophoresis and northern blot analysis were used to further characterize drug responses in sensitive and resistant cells. Treatment of the sensitive PC3 cells with VP-16 and CDDP resulted in accumulation of cells in S and G2, and G1 and S phases, respectively, and caused significant degradation of the genomic DNA into internucleosomal sized DNA fragments, indicating apoptosis. In contrast, resistant PC3 cells showed little or no DNA fragmentation. Resistant PC3(R) cells expressed 2-3-fold more bcl2 protein than the parental PC3 cells, and overexpressed c-myc, c-jun and H-ras mRNA compared to sensitive cells. Treatment with VP-16 or CDDP significantly induced c-myc mRNA levels in sensitive PC3 cells. H-ras message was not affected by either VP-16 or CDDP treatment in PC3 cells. These studies, taken together, suggest that a differential susceptibility to apoptosis and chemosensitivity may be related to altered levels of bcl2 and/or oncogene overexpression in PC3(R) cells.

Use of monoclonal antibodies for the analysis of mycotoxins

Hybridomas producing monoclonal antibodies against aflatoxin M1, ochratoxin A, zearalenone, T-2 toxin, diacetoxyscirpenol, 3-acetyl-deoxynivalenol, fusarenon X, and roridin A were developed after immunization of BALB/c mice and fusion of the splenocytes with myeloma cells. The antibodies were characterized in terms of immunoglobulin subclass, sensitivity, and specificity. The use of these antibodies in competitive enzyme immunoassays, either as microtiter plate assays or membrane-based quick tests, as well as for the production of immunoaffinity columns is described. The advantages and disadvantages of monoclonal antibodies compared to polyclonal antisera for the improvement of mycotoxin analysis are discussed.

DATATOP-study: significance of its results in the treatment of Parkinson's disease

There are a number of promissing findings suggesting a "neuroprotective" effect of selegiline in animal models of parkinsonism. In contrast thereto, neither the DATATOP study nor more recently reported clinical trials were able to clearly demonstrate an effect on the natural course of disease progression, especially as the analysis of the clinical findings is confounded by the symptomatic effect of selegiline. At present, treatment with selegiline in otherwise untreated parkinsonian patients allows to postpone the treatment with levodopa or to keep the levodopa dosage on a lower level.

Increased expression of the multidrug resistance-associated protein gene in relapsed acute leukemia

Quantitative reverse transcriptase polymerase chain reaction (RT-PCR) was used to determine relative levels of transcripts for MDR1 and the recently described multidrug resistance-associated protein (MRP) in normal lymphohematopoietic cells and in 62 bone marrow aspirates of newly diagnosed and recurrent acute leukemia. Levels of MRP expression in newly diagnosed AML samples were similar to those observed in normal bone marrow cells (CD34-negative and CD34-positive) and in unselected HL60 human promyelocytic leukemia cells, which were used as an internal control throughout this study. In contrast, samples of AML obtained at the time of relapse contained approximately twofold higher levels of MRP RNA (P < .01). Analysis of paired samples, the first obtained at diagnosis and the second at relapse, from 13 acute myelogenous leukemia (AML) and four acute lymphocytic leukemia (ALL) patients showed that MRP expression was increased at the time of relapse in greater than 80% of patients. In contrast, no consistent changes of MDR1 expression at relapse were observed. These results raise the possibility that increased MRP expression might contribute to leukemic relapse.

Practical library research: a tool for effective library management

Librarians are being urged to conduct research as one of their professional responsibilities. Many librarians, however, avoid research, because they believe it is beyond their capabilities or resources. This paper discusses the importance of conducting applied research-research directed toward solving practical problems. The paper describes how one library conducted practical research projects, including use studies and surveys, over an eighteen-year period. These projects produced objective data that were used by the library to make management decisions that benefited both the library and its parent institution. This paper encourages other librarians to conduct practical research projects and to share the results with their colleagues through publication in the professional literature.

Performance of Israeli versus U.S. preschool children on the Miller Assessment for Preschoolers

OBJECTIVES

The Miller Assessment for Preschoolers (MAP) is a scale that can be used to evaluate preschool children with suspected preacademic problems. Before implementing the MAP in Israel, it was necessary to determine whether the U.S. norms were applicable to the Israeli preschool population.

METHOD

In a pilot study carried out in Israel, the Hebrew version of the MAP was administered to 2 age groups of 30 children each. The scores of Israeli children were compared with the U.S. norms on each of the MAP's 27 subtests, the five performance indices, and the total score.

RESULTS

There were no significant differences between the Israeli sample and the U.S. standardization sample in either age group on the MAP total score; significant differences were found in both age groups on the Foundations Index and on some specific subtests. Israeli children performed below U.S. norms on the Foundations Index.

CONCLUSION

These findings indicate that the performance of Israeli children overall in these two age groups is not significantly different from the performance of U.S. children. If future research demonstrates that these findings are stable across all age groups and for larger samples, the implication is that the MAP can be administered and scored in Israel with the scoring methodology and normative information developed in the United States. However, because of the poorer performance of Israeli children on the Foundations Index, we recommend that specific Israeli norms be developed.

Immunochemical detection of antibiotics and sulfonamides

To control the maximum residue limits (MRLs) for residues of veterinary drugs in food of animal origin, according to EU regulations, a broad spectrum of sensitive analytical methods is required. One effective approach is the development of immunoassays, particularly for screening purposes. Strategies for the production of specific polyclonal and monoclonal antibodies against beta-lactams, tetracyclines, streptomycin, chloramphenicol, sulfonamides and trimethoprim, are outlined, as well as methods for the synthesis of the respective enzyme-labelled antigens. The sensitivity and the specificity of the antibodies were characterized, and the immunochemical test systems were designed as quantitative routine tests (microtitre plate format) and as rapid qualitative tests (membrane-based assay formats). The detection limits of the assays were found to be well below the regulatory limits. The range of recovery, for the analysis of artificially contaminated samples, was between 68 and 104%. In principle, the enzyme immunoassays for antimicrobial drugs showed the advantage of sensitivity and speed together with the simplicity of manipulations involved in the procedure. However, because of the results of the specificity studies, as well as the possibility of false positive results owing to unspecific inhibition of the assay, confirmation of immunoassay results is still required for all legal and statutory purposes.

Increasing melanoma incidence: putatively explainable by retrotransposons. Experimental contributions of the xiphophorine Gordon-Kosswig melanoma system

The worldwide accelerating increase of neoplasia in humans is difficult to explain. We use the Xiphophorus tumor model to approach this problem by melanoma provocation with X-rays. Melanoma develops following inappropriate expression of x-erb B-conducted developmental genes and their controllers. These oncodeterminants are inherited according to Mendelian rules. We detected a new type of oncodeterminants that, following a single treatment of embryos with X-rays, generates a self-generating non-Mendelian melanoma transmission and accelerating increase of its incidence in succeeding generations (e.g., 0-->18-->33-->52%). To localize these oncodeterminants, we crossed nonirradiated fish having half of their chromosomes irradiated with nonirradiated fish having none of, half of, or all of their chromosomes irradiated. Because tumor rate and expression in the following generations correspond to the rates of treated chromosomes, we conclude that the new oncodeterminants are distributed over the chromosomes of the fish, where they may increase in the changing generations. By means of xiphophorine-specific retroviral DNA, we isolated two retrotransposons that behave hereditarily like the new transgenerational oncodeterminants. Sequence analysis revealed three ORFs flanked by LTRs containing motives of regulatory sequences typical for known retroviral and retrotransposal LTRs. Pol- and env-resembling sequences are lacking. Southern and in situ hybridization showed their multiple and repetitive nature distributed throughout the chromosomes and indications for their capability to increase in number without further treatment. Their transcripts are expressed in concert with those of most of the other known xiphophorine tumor determinants. Their expression is extremely high in cell cultures from tumorous embryos derived from ancestors treated as embryos with X-rays.