Metal-binding chimeric antibodies expressed in Escherichia coli

Metallothionein, a well-characterized biological chelator of metals, has been genetically fused to the binding domain of an antibody and expressed in the periplasm of Escherichia coli. Specific delivery of 109Cd to immobilized hapten or to haptenated cells was demonstrated directly in periplasmic extracts. This approach is potentially useful for targeted radiotherapy and diagnostic imaging. We find six to seven atoms of metal per active antigen-combining site. Absence of the Fc portion of the immunoglobulin along with low immunogenicity of metallothionein-metal complexes should reduce immunologic reactions.

Traditional and molecular cytogenetics

Traditional cytogenetic methods have relied on tissue culture techniques to generate adequate mitotic cells for the analysis of chromosome disorders for prenatal diagnosis. Chromosome banding techniques allow the evaluation of mitotic cells for structural and numerical aberrations and define the nature of any rearrangement. With the advent of fluorescent in situ hybridization methodology, which combines the molecular technologies of chromosome-specific probes and in situ molecular hybridization, it has become possible to analyze chromosomal numerical and structural aberrations from interphase cells. The use of molecular cytogenetic techniques should greatly increase the speed and diagnostic resolution of clinical specimens.

Telomeric associations evolving to ring chromosomes in a recurrent pleomorphic xanthoastrocytoma

Telomeric associations observed in a recurrent untreated pleomorphic xanthoastrocytoma were apparently the primary cytogenetic events that evolved by fusion and breakage events, resulting in subclones with ring chromosomes. The telomeric fusions between chromosomes 15pter and 20qter, and between an extra copy of the long arm of chromosome 1 and chromosome 22qter, evolved in a stepwise fashion to ring chromosomes 20 and 22. The findings in this tumor demonstrate that telomeric association is one mechanism that can initiate chromosome instability by generating subclones with unstable chromosome intermediates and result in ring chromosomes and subsequent chromosome loss.

A novel reciprocal chromosome translocation t(11;22)(p13;q12) in an intraabdominal desmoplastic small round-cell tumor

We report an intraabdominal desmoplastic small round-cell tumor that contains a novel reciprocal chromosome translocation t(11;22)(p13;q12). The tumor showed a reciprocal chromosome translocation which is different from the (11;22)(q24;q12) translocations seen in Ewing's and other small-cell tumors but affects the same break-point on chromosome 22(q12). This reciprocal chromosome translocation may prove to be a marker for intraabdominal desmoplastic small round-cell tumors.

Rapid detection of antigen binding by antibody fragments expressed in the periplasm of Escherichia coli

Bacterial expression systems can greatly facilitate protein engineering of antibodies. We have developed a system for high-level expression of antibodies, antibody fragments, or hybrid antibodies with novel effector functions in the periplasm of Escherichia coli. From 5 ml of cells, a simple extraction yields sufficient material for SDS-gel electrophoresis, detection and characterization of hapten binding. To demonstrate our system, heavy-chain variable regions and lambda 1 light chains of a mouse anti-NP antibody were synthesized as hybrid proteins with a bacterial signal peptide (Omp F). Each chain is secreted into the periplasm where processing (cleavage of the signal peptide), folding and heterodimer association take place. Periplasmic proteins are released by cold osmotic shock, and hapten-binding activity is easily detected without further manipulation. The ease of genetic engineering in this system will facilitate the production of immunoglobulin derivatives designed for specific applications, and expression of these molecules in a native state will allow the rapid screening of combinatorial libraries and the results of mutagenesis.

Molecular cytogenetic analysis of a medulloblastoma with isochromosome 17 and double minutes

Cytogenetic analysis of a medulloblastoma revealed two abnormal cell lines of 48,XY, +8, +8, -14, +der(14)t(1;14)(q11;p11),i(17q) and 51,XY, +5, +6, +8, +8, -14 + 20, +der (14)t(1;14)(q11;p11),i(17q), + dmin. The finding of double minute chromosomes in some medulloblastomas has been associated with amplification of the c-myc or N-myc oncogenes. We were unable to detect gene amplification with these probes by Southern blot analysis.

Cytogenetic findings in a pleomorphic xanthoastrocytoma

We report a pleomorphic xanthoastrocytoma with an abnormal clonal cell line of 48,XY, +3, +5, -20, -22, +der(7)t(7;?)(p22;?), +der(20)t(15;20)(q11;q13).

Evolution of tumor chromosome abnormalities after therapy in a pediatric astrocytoma

Chromosome studies originally performed on a patient with an untreated pontine astrocytoma showed a trisomy for 1q as the sole chromosome aberration. After the patient received radiation and chemotherapy, subsequent study indicated the presence of the original trisomy for 1q, as well as trisomy for chromosomes 2, 3q, and 17, in a tumor that now, histologically, is glioblastoma multiforme. In addition to the numerical aberrations, chromosome rearrangements were observed, involving translocation breakpoints that have been reported as "hot spots" associated with the clastogenetic effect of ionizing radiation.

Highly conserved segments in mammalian chromosomes

Mammalian chromosomes from seven species for which gene maps exist were studied by high-resolution techniques to identify areas of conserved chromosome banding homology. High-resolution comparisons of human, chimpanzee, gorilla, orangutan, African green monkey, cat, and mouse chromosomes revealed regions of apparently conserved chromosomal banding, which may indicate the likely positions of conserved linkage in the phylogeny of mammals. This analysis indicates that many regions of subbanding homology may have remained intact during the evolution of mammals and reflects a high degree of chromosome conservation in diverse species.

Cytogenetic studies of pediatric brain and spinal cord tumors

Seventy pediatric patients with brain and spinal cord tumors had cytogenetic analysis of 99 samples of their tumors. Successful analysis was accomplished in 95%. Tumors included 43 gliomas, 9 medulloblastomas and a variety of other lesions. Forty-three patients had normal chromosomes; 28 of these had benign tumors and good outcomes. Of 11 patients with malignant tumors and normal chromosomes, 8 have no disease or stable disease during the period of follow-up. Outcomes of the 23 patients with abnormal chromosomes were poor; 17 had malignant pathology. Six patients with 'benign' disease and abnormal chromosomes died or have progressive disease. A relationship between outcome and pathologic diagnosis is often enhanced by cytogenetic findings. The study indicated specific chromosome abnormalities in certain pediatric brain tumors, such as chromosome 1 abnormalities in gliomas and isochromosome 17 abnormalities in medulloblastomas. It is recommended that cytogenetic studied be included in cooperative therapeutic trials. The clastogenic effects of treatment on the cytogenetic characteristics of tumors sequentially studied were demonstrated, as was the role of sampling variations. Attention to the treatment history of tumor samples, as well as evaluation of multiple samples from each tumor, may improve the reliability of cytogenetic studies.

Trisomy for chromosome 1q in a pontine astrocytoma

Reports of single chromosome abnormalities in pediatric brain tumors are rare. We report a 6-year-old patient with a malignant astrocytoma who had trisomy for the long arm of chromosome 1 as the sole chromosome abnormality.

Progression of chromosome abnormalities after radiation therapy in a patient with Askin's tumor

A patient previously reported to have Ewing's sarcoma showed a t(11;22) (q23;q11) and spontaneous expression of fra(11)(q23) [1]. Subsequent review of pathologic specimen indicated, however, that it was an Askin's tumor. Reciprocal translocations of chromosomes 11 and 22 are the most common cytogenetic abnormalities in Ewing's sarcoma and the related Askin's tumor. After radiation therapy of a residual metastatic brain lesion, subsequent studies of the recurrent brain tumor indicated the presence of the original translocations as well as five new reciprocal translocations and two deleted segments (9p-, 10p-). The new chromosome abnormalities were consistently found, indicating that progression of the tumor was clonal. The newly observed clonal aberrations were considered secondary in nature. A relationship between craniocerebral irradiation and development of brain tumors has been reported in several studies, but the mechanism for tumor induction has not yet been elucidated. It is important that the role of radiation therapy in the evolutionary process of chromosomal changes be studied in a large group of similar cases.

High-resolution cytogenetic characterization of the L5178Y TK+/- mouse lymphoma cell line

High-resolution chromosome preparations from L5178Y TK+/- 3.7.2C mouse lymphoma cells were obtained using acridine orange in the cell harvest procedure. With this technique it is possible to visualize over 500 bands in elongated mouse lymphoma cell chromosomes as compared to the approximately 230 bands visualized in metaphase preparations. High-resolution lymphoma cell chromosomes are described, and chromosome rearrangements carried in the cell line are characterized by ideograms representing the position, number, size, and relative staining intensity of the G-band patterns. Use of elongated chromosomes of mouse lymphoma TK+/- mutants should facilitate analysis of the cytogenetic effects associated with TK+/- ----TK-/- mutagenesis.

High-resolution cytogenetic analysis of L5178Y TK+/- 3.7.2C cells: variation in chromosome 11 breakpoints among small-colony TK-/- mutants

Since the finding that the mouse lymphoma L5178Y TK+/- ----TK-/- forward mutational assay system can detect and distinguish a range of genetic lesions, including large chromosomal aberrations and smaller, perhaps point mutational events, the chromosomal analysis of these lesions at the highest possible level of band resolution has become increasingly important. We have developed an acridine orange/colcemid/hypotonic treatment for TK-/- mutants to provide high-resolution chromosomes with over 500 G-bands for breakpoint analysis. Using such high-resolution procedures, we find that independently induced small-colony mutants show rearrangements in the distal portion of chromosome 11, with breakpoints occurring between bands B3 and E1.2. This finding of a range of chromosomal breakpoints in different TK-/- mutants complements recent molecular genetic analysis of mutants and is consistent with the hypothesis that chromosomal lesions in small-colony mutants may affect a large portion of the genome in the vicinity of the tk-1 gene.

Methapyrilene is a genotoxic carcinogen: studies on methapyrilene and pyrilamine in the L5178Y/TK +/- mouse lymphoma assay

Methapyrilene (MP), a sedating antihistamine, is a potent rat hepatocarcinogen which has been thought to be non-genotoxic on the basis of the negative results in a small number of short-term mutagenicity tests. The present studies show that MP is a moderately active mutagen in the L5178Y/TK +/-----TK-/- mouse lymphoma assay (MLA) in the presence of aroclor-induced rat-liver S9, and that it induces predominantly small-colony thymidine kinase-deficient (TK-/-) mutants of demonstrated chromosomal origin. 10 of 12 small colony TK-/- mutants analyzed by banded karyotype (230-band level of resolution) show aberrations to chromosome 11b, the known location of the single functional TK gene in these cells. The observed aberrations from nine of the mutants included insertions, deletions and translocations while the tenth mutant had highly rearranged, multiple copies of chromosome 11 segments. By varying the concentrations of the S9 protein and cofactors it was shown that our standard S9 composition was close to optimum for activating MP to a mutagen. The activity and stability of various lots of S9 prepared in-house or purchased from a contract laboratory revealed significant differences. The ability of 2 lots of in-house S9 to activate a standard concentration of MP increased rapidly over the first 4 weeks of liquid nitrogen storage then declined slowly over the next 16 weeks. Three separate lots of purchased S9 were essentially inactive for the first 2 weeks of liquid nitrogen storage then increased in activity thereafter; these were the only occasions in which MP was not mutagenic in our hands. The mutagenic activity of pyrilamine (PYR), a structurally related antihistamine which is far less carcinogenic in rats, but easily detected in short-term tests as being genotoxic, was also investigated in the MLA. PYR was slightly less mutagenic than MP over a comparable range of concentrations, and also induced predominantly small-colony mutants. These studies fail to adequately explain the great carcinogenic differences between these two compounds, but are consistent with the potent hepatocarcinogenicity of MP resulting through a mutagenic mechanism.

High resolution G-banded chromosomes of the mouse

High resolution G-banded mouse chromosomes were prepared using an actinomycin D and acridine orange pretreatment protocol, resulting in late prophase mouse chromosomes which reveal over twice the number of bands as compared with mid metaphase. These elongated chromosomes, described here in detail and used to construct a precise schematic representation of the late prophase banding patterns, should be generally useful in high resolution mouse chromosome analysis.

High resolution of mouse chromosomes: banding conservation between man and mouse

A detailed schematic representation of high-resolution G-banding patterns was prepared from elongated and finely banded mitotic chromosomes of the mouse. Such chromosomes can be obtained from both animal tissue and cell lines by a simple protocol, facilitating precise demarcation of breakpoints in chromosome rearrangements and aiding in the sublocalization of genes. Regions of subbanding homology were observed between human and mouse chromosomal segments known to have conserved gene assignments, an indication that, at the cytogenetic level, extensive regions of the mammalian genome may remain intact after 60 million years of species divergence.

G-banding patterns of high-resolution human chromosomes 6--22, X, and Y

A precise schematic representation of the number, height, position, and staining intensity of the Giemsa bands of late prophase, prometaphase, early metaphase, and mid-metaphase chromosomes 6--22, X, and Y is presented. Late prophase chromosomes were found to have 2--2 1/2 times the length and 3--3 1/2 times the number of bands previously observed in mid-metaphase, whereas prometaphases and early metaphases were intermediate in length and number of bands. In this work, the maximum number of bands observed per haploid set in late prophase was 1353, while more than 350 were generally found in mid-metaphase.

The characterization of high-resolution G-banded chromosomes of man

The detailed characterization of G-banding patterns of high resolution human chromosomes has been possible with the utilization of a refined cell synchronization technique which routinely yields a large number of excellent quality cells in late prophase, prometaphase, early metaphase, and mid-metaphase. The mitotic cells exhibit up to a 400% increase in the number of bands previously visualized by standard methods. From studies of the banding patterns, it has become evident that the G-positive and, to some extent, the G-negative bands of mid-metaphase results from a coalescence of finer subbands of earlier stages and that each band and its corresponding subbands maintain a constant location throughout the process of chromosome condensation. A precise schematic representation of the number, position, height and staining intensity of bands is presented for the five largest chromosomes of the complement at the four mitotic stages.

The G and Q banding pattern of Ellobius lutescens. A unique case of sex determination in mammals

The karyotype of the microtine Ellobius lutescens Th., was analysed using the G and Q banding techniques. One of the chromsomes of the first pair has the same bands in both sexes while the other member of the pair is unique to each sex. We propose that the sex determining mechanism of Ellobius lutescens is located in these chromosomes. The genetic burden imposed on this species due to this constitution is discussed.