Possible role of 06-methylguanine-DNA-transferase in the response of patients with primary tumor of the brain to chemotherapy using chloro-ethyl-nitroso-urea: results of a current study

We have started a study to measure the MT activity in surgical specimens from high grade human malignant gliomas, with the dual aim to (i), know whether lack of activity can be demonstrated in these tumors, and (ii), relate the measured levels of MT to the histology of the tumors and to the response of patients to chemotherapy with 1-(2-Chloroethyl)-3-Cyclohexyl-1-Nitrosourea (CCNU). To date, 12 Gliomas have been assayed. In 11 tumors, MT activities ranging from 30 to 150 fmoles/mg protein have been measured. The only negative specimen derived from a patient who had received radiotherapy before surgery. At the present stage of the study, therefore, we have no unequivocal evidence for the existence of MT-deficient Gliomas.     

Poly(ethylene oxide)-grafted thermoplastic membranes for use as cellular hybrid bio-artificial organs in the central nervous system

Poly(acrylonitrile-co-vinyl chloride) (PAN/VC) anisotropic membranes were chemically modified with poly(ethylene oxide) (PEO) (5000 and 20,000 g/mol) by one of two aqueous reactions: (a) acid hydrolysis of the nitrile group to a carboxylic acid with which amine-terminated PEO (PEO-NH(2)) reacted or (b) base reduction of the nitrile group to an amine with which PEO-succinimide (PEO-SC) reacted. Approximately 1.3% of the bulk material was modified with PEO-NH(2) whereas 1.8 to 3.5% was modified with PEO-SC as determined by proton nuclear magnetic resonance ((1)H NMR) and attenuated total reflectance Fourier transform infrared (ATR FTIR) spectra. Approximately 50 to 75% less bovine serum albumin (BSA) adsorbed to PEO-grafted single skin fibers than to unmodified PAN/VC. Transport properties of modified and unmodified fibers were compared by passive diffusion, convective nominal molecular weight cutoff, and hydraulic permeability. Neither hydraulic permeability nor nominal molecular weight cutoff of BSA changed appreciably after surface modification with PEO indicating that pore structure was not adversely affected by the chemistry involved in grafting poly(ethylene oxide). However, in the absence of any membrane conditioning, the apparent diffusion of alpha-chymotrypsinogen (24,000 g/mol) was enhanced in PEO-grafted PAN/VC fibers possibly as a result of reduced sorption of the permeating protein. In vivo biocompatibility in the brain tissue of rats was judged by histological assessment of the host's cellular response to fibers implanted for 30 days; biocompatibility of both PAN/VC and PAN/VC-g-PEO was satisfactory but improved slightly with PEO grafting. (c) 1994 John Wiley & Sons, Inc.     

Exclusion of the APC gene as the cause of a variant form of familial adenomatous polyposis (FAP)

Familial adenomatous polyposis (FAP) is a premalignant disease inherited as an autosomal dominant trait, characterized by hundreds to thousands of polyps in the colorectal tract. Recently, the syndrome has been shown to be caused by mutations in the APC (adenomatous polyposis coli) gene located on chromosome 5q21. We studied two families that both presented a phenotype different than that of the classical form of FAP. The most important findings observed in these two kindreds are (a) low and variable number of colonic polyps (from 5 to 100) and (b) a slower evolution of the disease, with colon cancer occurring at a more advanced age than in FAP in spite of the early onset of intestinal manifestations. To determine whether mutations of the APC gene are also responsible for this variant syndrome, linkage studies were performed by using a series of markers both intragenic and tightly linked to the APC gene. The results provide evidence for exclusion of the APC gene as the cause of the variant form of polyposis present in the two families described.     

Immunoadjuvant effects of Candida albicans and its cell wall fractions in a mouse lymphoma model

Summary Chemical, ultrastructural, and immunoadjuvant properties of Candida albicans (CA) and of a number of its fractions have been characterized through the analysis of the antitumor activity of soluble and insoluble cell wall components.CD2F₁ mice were inoculated IP with Moloney virus-induced lymphoma LSTRA and treated with bis-1-chloroethyl-nitrosurea (BCNU) on day +5 after tumor challenge. A significant increase of the antitumor efficacy of BCNU treatment was found in mice inoculated with CA as immunoadjuvant on days –14 and +1 (–14/+1 schedule) with respect to tumor challenge.However, no significant difference in survival time was found between mice treated with BCNU alone and those treated with BCNU plus either soluble mannan or glucan-protein fractions extracted from CA and administered according to –14/+1 or –7/+1 schedules. On the other hand, mice treated with BCNU plus the insoluble glucan fraction (wall ghosts) given on days –14/+1 or even on day –7 only (i.e., without boosting after tumor challenge) survived longer than animals treated with BCNU alone.The immunoadjuvant effect of CA and of other classic immunoadjuvants, such as BCG and Corynebacterium parvum, was completely abolished by total-body irradiation (400 R) given 5 h before the first administration of the agent on day –7 prior to tumor challenge.These results indicate that: (a) the minimal structure required for the expression of the immunoadjuvant effect of CA is the insoluble, -glucan component of the cell wall; (b) the soluble components of CA cell wall (i.e., mannan and glucan-protein) per se do not show any detectable immunoadjuvant effect in the present animal-tumor system; they may, however, modulate this effect, as shown by the fact that whole CA, but not the insoluble -glucan, needs a boosting injection for the expression of its immunoadjuvant properties; (c) the immunoadjuvanticity of CA is radiosensitive.     

Inhibiton by sulfanilamide of sporulation in Saccharomyces cerevisiae.

The antimetabolite sulfanilamide inhibits sporulation in Saccharomyces cerevisiae strain AP1. Cells exposed to sulfanilamide at various times during the sporulation process become progressively insensitive to the drug, although accumulation of sulfanilamide by the cells increases with time. Vegetative growth of AP1 is practically unaffected by sulfanilamide; pregrowth of the cells in the presence of the drug does not prevent sporulation. Thus, inhibition is confined to the meiotic phase of the cell cycle. Sensitivity to sulfanilamide is independent of pH. Increasing the time cells are exposed to sulfanilamide results in a progressive reduction of ascus formation; however, the inhibition is reversible since sporulation can occur in cells exposed to the drug for greater than 24 h. The drug arrests the cells at a point before commitment to sporulation, since yeast cells exposed to sulfanilamide for 12 h do not complete the sporulation process when returnedto vegetative medium, but resume mitotic growth instead. Meiotic nuclear division is largely prevented by sulfanilamide, and synthesis of RNA and protein is severely retarded. DNA synthesis is inhibited up to 50%; glycogen synthesis is approximately 90% inhibited. Other yeast strains showed varying sensitivity to sulfanilamide; homothallic strains were generally less affected.     

Isolation and characterization of cDNA clones to mouse macrophage and human endothelial cell tissue transglutaminases.

The deduced amino acid sequences for tissue transglutaminases from human endothelial cells and mouse macrophages have been derived from cloned cDNAs. Northern blot analysis of both tissue transglutaminases shows a message size of approximately 3.6-3.7 kilobases. The molecular weights calculated from the deduced amino acid sequences were 77,253 for human endothelial tissue transglutaminase and 76,699 for mouse macrophage tissue transglutaminase. The deduced amino acid sequence for the human endothelial transglutaminase was confirmed by comparison with the amino acid sequence obtained by cyanogen bromide digestion of the human erythrocyte transglutaminase. The amino acid sequences of both human endothelial and mouse macrophage tissue transglutaminases were compared to other transglutaminases. A very high degree of homology was found between human endothelial, mouse macrophage, and guinea pig liver tissue transglutaminase (greater than 80%). Moreover, human endothelial tissue transglutaminase was compared with human Factor XIIIa and a very high degree of homology (75% identity) was found in the active site region.     

Binding of matrix attachment regions to lamin B1.

Eukaryotic chromatin is organized into topologically constrained loops that are attached to the nuclear matrix. The regions of DNA that interact with the matrix are called matrix attachment regions (MARs). We studied the spatial distribution of MAR-binding sites in the nuclear matrix from rat liver cells, following a combined biochemical and ultrastructural approach. We found that MAR-binding sites are distributed equally over the internal fibrogranular network and the peripheral nuclear lamina. Internal and peripheral binding sites have similar binding characteristics: both sets of binding sites show specific and saturable binding of MARs from different organisms. By means of a DNA-binding protein blot assay and in vitro binding studies, we identified lamin B1 as a MAR-binding protein, which provides evidence for a specific interaction of DNA with the nuclear lamina.