CGP 6809 — A new nitrosoureido-sugar derivative with activity in human tumor xenografts

Summary CGP 6809 [ethyl-6-deoxy-3,5-di-O-methyl-6-(3-methyl-3-nitrosoureido)--d-glucofuranoside] is a new methylnitrosoureido-sugar derivative that has been shown to be active against a broad spectrum of transplantable tumours in mice and rats [14]. We investigated the anti-tumour effect of CGP 6809 in ten selected, human tumour xenograft lines growing s. c. in nude mice. The p. o. administration of 125 mg/kg per day for 10–15 days was less toxic (lethality 12% in tumour-bearing nude mice) than the i. p. injection of 62.5 mg/kg per day (lethality 22%). The anti-tumour effect was similar for both application routes; two large bowel cancers responded to treatment with CGP 6809, rectal cancer CXF 158 showed a remission, and the rapidly growing, undifferentiated colonic cancer CXF 280 exhibited a transient no-change. Furthermore, remissions were observed in the epidermoid lung cancer LXF 322 and in thyroid cancer 117. Tumour progression was found in another epidermoid lung cancer and in three stomach cancers, one melanoma, and one soft tissure sarcoma. CGP 6809 is a promising new agent for clinical trials, especially for large bowel and epidermoid lung cancer.Supported in part by grant PTB 8467 from the Bundesminister für Forschung und Technologie, Bonn, FRG     

Expression of human immunodeficiency virus type 1gag gene using genetically engineered herpes simplex virus type 1 recombinants

Infectious herpes simplex virus type 1 (HSV-1) recombinants were constructed by inserting the cDNA sequence of the human immunodeficiency virus type 1 (HIV-1)gag gene (from nucleotide position 675 [SacI] to 3859 [Asp 718] of the cDNA sequences of HIV-1 strain BH-10) within the DNA sequences of theBamHI DNA fragment B of the genome of an apathogenic HSV-1 strain HFEM. This HSV-1 strain possesses a 4.1-kbp deletion within theBamHI DNA fragment B between 0.762 and 0.789 map units of the viral genome, which allows the insertion of at least 4 kbp of foreign genetic material into this particular region. The DNA sequences of the immediate early promoter (IE4) of HSV-1 that were inserted upstream from thegag gene were used as a promoter. The screening of 205 virus stocks derived from individual plaques revealed that 46 recombinant viruses harbor HIV-1gag-specific DNA sequences. However, it was found that only six of the recombinant viruses are able to express thegag gene product of HIV-1. This indicates that the ratio of the positive recombination events is about 2.9%.     

Decreased prefrontal 5-HT2A receptor binding in subjects at enhanced risk for schizophrenia

The brain serotonin-2A receptor (5-HT_2AR) has been implicated in both the pathology of schizophrenia and the therapeutic action of atypical antipsychotics. However, little is known about the 5-HT_2AR status before the onset of schizophrenia and before the exposure to antipsychotics. We used [¹⁸F] altanserin and positron emission tomography (PET) in a pilot study of 6 individuals suspected to be at elevated risk for schizophrenia and seven age-matched controls to test the hypothesis that regional 5-HT_2AR binding is altered in the prodromal stages of schizophrenia. Distribution volume ratios (DVRs) as a proxy for 5-HT_2AR availability were significantly reduced in prefrontal cortex regions of at-risk subjects, implicating early abnormalities of serotonergic neurotransmission that antecede the onset of schizophrenia.     

Conductance properties and voltage dependence of an anion channel in amphibian skeletal muscle

Single anion-selective channels were studied in excised membrane patches of adult frog toe muscle. The conductance and the probabilityp _o of the main open state were determined for various ionic compositions of the extra-and intracellular solutions. =280 pS in symmetrical 110 mM NaCl, pH 7.4 solutions at 15°C. Higher values were found at elevated internal or external NaCl concentrations, in 70 mM external CaCl₂ and at lower extracellular pH. Thep _o(E) curve declined steeply with hyperpolarization and was shifted towards more negative potentials at increased internal ionic strength and at higher external pH. Positive shifts were induced by extracellular Ca. The results show that the anion channel saturates at Cl concentrations >110 mM, that the potential profile of an open channel is almost symmetrical and that channel gating is affected by neighboring channels. It is suggested that the anion channel has a voltage sensor (effective gating charge 4.3) and a similar collection of local fixed charges on the extra- and intracellular sides as voltage-gated cation channels.     

Low dose exposure to sodium arsenite synergistically interacts with UV radiation to induce mutations and alter DNA repair in human cells

Inorganic arsenic is a known human carcinogen, yet its mechanism of action remains poorly understood. Epidemiological data suggest that arsenic exposure interacts with UV radiation exposure to increase the risk of skin cancer. Studies have suggested that arsenic is able to impair DNA repair enzymes and alter the repair of UV-induced DNA damage. Here we have tested the hypothesis that arsenite [As(III)] and UV interact synergistically to enhance mutagenesis. TK6 human lymphoblastoid cells that are functionally heterozygous at the thymidine kinase (TK) locus were pre-exposed to As(III) alone and in combination with UV. Our data suggest that As(III) is mutagenic only at high doses at the TK locus. As(III) enhanced UV mutagenesis in a more than additive fashion. To investigate the mechanism underlying this synergy we assessed the removal of UV-induced dimers in TK6 cells using the T4 endonuclease-incorporated Comet assay. Pre-treatment with As(III) specifically inhibited the repair of UV-induced pyrimidine dimer-related DNA damage. Taken together, these data suggest that pre-treatment of human cells with arsenic impairs the nucleotide excision repair pathway and leads to enhanced UV mutagenesis.     

Developmental aspects of children's behavior and safety while cycling

OBJECTIVE: To examine children's competence while cycling, as demonstrated in mistakes in performance and failure to comply with safety rules. METHODS: Children in three age groups (8, 10, and 12 years) participated in a realistic yet simulated traffic environment. RESULTS: The boys' cycling speed increased steadily with age, while that of the girls increased from 8 to 10 but decreased at age 12. Most children had adequate motor control by age 10, and the youngest compensated for their less developed skills by cycling slowly and braking early at junctions. Serious mistakes, often related to the children's age and gender, consisted of the children failing to stop at signals or stopping too late, especially at short stopping range. CONCLUSIONS: There are considerable individual differences in children's cycling competence that are related to biological factors, such as age and gender, and psychological factors, such as rule compliance and choice of cycling speed.     

Metameriest?rungen und ihre Konsequenzen im S?ugetierexperiment

Zusammenfassung Störungen der Segmentierung werden bei der Hausmaus durch die Erbfaktoren Crooked tail und Rib fusions wie auch durch weitere Gene hervorgerufen. Eine Phänokopie der Mutation Rib fusions durch Sulfonylharnstoff (Rastinon) wird beschrieben. Als Ursache der beobachteten Wirbel-Rippenmißildungen ist eine Störung der Zellaggregation zu betrachten, die sich durch alle Entwicklungsphasen bis zur knöchernen Fehlbildung auswirkt.Die empfindliche Phase ist die Heraussonderung der Ursegmente aus dem undifferenzierten Mesoblasten. Ihre Beeinflussung, speziell durch hypoglykämische Agentien, wird nach Ort und Zeit analysiert und die Entwicklung der entstehenden Mißbildung untersucht.Es wird die Hypothese aufgestellt, daß in dieser Phase ein erhöhter Energiebedarf besteht, der durch eine Störung der Oxydationsprozesse blockiert werden kann.Ausgeführt mit Hilfe der Stiftung für wissenschaftliche Forschung an der Universität Zürich.     

Antibody-bearing liposomes as multicolor immunofluorescence markers for flow cytometry and imaging

Loposomes covalently coupled to monoclonal antibodies retain the specificity of the antibody and bind only to cells bearing the appropriate determinant. As opposed to directly labeled antibodies which generally have fluorochrome to protein ratio of between 2–5, the entrapped space inside liposome can contain several hundred to several thousand molecules of fluorochromes in a space chemically isolated from the outside environment, thus providing the potential for an amplified fluorescence signal. We have prepared small unilamellar liposomes containing the soluble fluorochromes carboxyfluorescein (CF), which fluoresces in the green and sulforhodamine (SR), which fluoresces in the red, and covalently coupled a series of monoclonal antibodies using a heterobifunctional reagent. We were able to detect, on an Epics 753 flow cytometer equipped with an argon ion and a dye laser and by fluorescence microscopy, both single and double labeled mouse spleen lymphocyte subsets, fibroblast L cells and Raji cells. Complete color separation was obtained with CF-labeled cells being detected only by the green photomultiplier and SR-labeled cells by the red photomultiplier. Cells labeled with both were detected by both photomultipliers. Liposomes bearing anti-Ia antibodies bound only to B lymphocytes whereas those with anti-H-2K antibody bound both to T and B lymphocytes. In another system, single and dual color immunofluorescence made possible the simultaneous detection of HLA and H-2K molecules on transfected murine fibroblast L cells. The signal-to-noise ratio was more favorable for the liposome-labeled reagents than reagents labeled with fluorescein isothiocyanate. Cells labeled with antibody-bearing liposomes could be fixed with paraformaldehyde or glutaraldehyde without adversely affecting the original staining patterns. Apart from the two fluorochromes described above, other markers of choice could be encapsulated without any adverse effect on the antibody-liposome coupling procedure or on the specificity of the conjugated antibody. Since the fluorochrome is not directly coupled to the protein, there is no requirement for protein conjugation sites in order for it be usefully encapsulated inside liposomes. Therefore, this system provides new opportunities to exploit different, as yet untapped fluorochromes for use in flow cytometry and imaging.