Spatial memory in aged rats: population heterogeneity and effect of levocarnitine acetyl

The existence in a population of aging rats of classes that display a different performance in the Morris water-maze test was investigated by cluster analysis procedure. These classes identified at 18 months of age showed a different response to levocarnitine acetyl and had a different behavioral profile when tested at 25 months of age. These findings demonstrate the need for an alternative interpretation of variability in animal populations as measured by the standard statistical analyses. The data analysis strategy we propose here will allow for the use of variability as a useful source of information.

Mathematical models for exploring different aspects of genotoxicity and carcinogenicity databases

One great obstacle to understanding and using the information contained in the genotoxicity and carcinogenicity databases is the very size of such databases. Their vastness makes them difficult to read; this leads to inadequate exploitation of the information, which becomes costly in terms of time, labor, and money. In its search for adequate approaches to the problem, the scientific community has, curiously, almost entirely neglected an existent series of very powerful methods of data analysis: the multivariate data analysis techniques. These methods were specifically designed for exploring large data sets. This paper presents the multivariate techniques and reports a number of applications to genotoxicity problems. These studies show how biology and mathematical modeling can be combined and how successful this combination is.

What indication is common to different genotoxicity data bases?

This paper studies the relationships among 4 in vitro assays: Salmonella mutation (STY), mouse lymphoma L5178Y cell mutation (MLY), chromosomal aberrations in CHO cells (CHA), and sister-chromatid exchanges in CHO cells (SCE), in 3 different data bases: U.S. National Toxicology Program (NTP), International Program for the Evaluation of Short-Term Tests for Carcinogens (IPESTTC), and International Program on Chemical Safety (IPCS). The analysis is performed by modeling each data base with factor analysis. With this tool, it has been possible to separate the different elements (or components) which play a role in each data base. It has also been possible to demonstrate that--together with some specificities of the data bases--there is a common effect which is independent of the data bases, and which typically represents the 'true' relationships among the assays. This element explains 69% of the information contained in NTP, 50% of that of IPESTTC, and 30% of that of IPCS. This common evidence indicates that the responses of STY and CHA to the 'universe' of chemicals are relatively similar, although STY is a bacterial mutation system and CHA is a mammalian cell test for chromosomal damage. The other similarity apparent from this analysis is the one between MLY (mutation in mouse cells) and SCE (cytogenetic evidence in hamster cells). The implication of this result is 2-fold. On the one hand, it is extremely reassuring that the 3 most important comparative studies agree and show common evidence, and this can be recognized rationally. On the other hand, this evidence implies that the scientists involved in mutagenicity research must face the task of exploring and explaining such relationships.

Spatial learning and memory in the radial maze: a longitudinal study in rats from 4 to 25 months of age

This longitudinal study was designed to investigate whether previous experience may influence performances and strategies of rats tested in the radial maze without external cues when aged 4, 13, and 25 months. Their performances and strategies were compared with those of another group of rats tested only when aged 25 months. Expert old animals showed a good retention of previous experiences, whereas age-matched nonexpert animals exhibited some acquisition deficits. On the contrary, in the course of aging, the animals kept modifying their strategies independently of experience. In summary, we can conclude that previous experience is likely to influence performances of the aged rat but not the strategies adopted which are strictly age-dependent and independent of acquired experience.

Increased osmiophilia of glycosaminoglycan-like structures after fixation with cetylpyridinium chloride in human colonic mucosa

The effects on tissue ultrastructural appearance of fixation with cetylpyridinium chloride (CPC)-additioned formaldehyde were studied at the ultrastructural level in human colonic mucosa. We found that CPC did not impair tissue morphology and induced a remarkable osmiophilia in glycosamino-glycan-like structures, which did not require further staining.

Sulphated glycosaminoglycans expression in the basement membranes of colorectal adenocarcinomas. Preliminary study: correlation with histological grading

The expression of sulphated glycosaminoglycans was studied at the ultrastructural level by the high iron diamine technique in the basement membranes of 26 colorectal adenocarcinomas (10 well-differentiated, 7 moderately-differentiated, 9 poorly-differentiated). Sulphated glycosaminoglycan expression was highly variable. It was scored as regular (5 cases), slightly irregular (6 cases), highly irregular (15 cases). In general, poor histological differentiation could be correlated with absent or highly irregular expression. However, in a limited number of cases, severe alterations of basement membranes were also present in well-differentiated (2 cases) and moderately-differentiated (4 cases) tumours. Such a variability shows up a heterogeneity which is not revealed by histological grading.

A 33 kDa protein band is enhanced during long-term adaptation of EUE cells to a hypertonic medium

A cell line derived from human embryonic epithelium (EUE cells) shows an enhanced expression of a 33 kDa protein when adapted to grow in a hypertonic medium containing 0.246 M NaCl (1.8 x the isotonic concentration). The maximum amount of this protein, followed by SDS-PAGE electrophoresis, was found after 4 days of adaptation; thereafter, the protein band remained fairly constant up to 30 days. When the cells were transferred back to a medium containing 0.137 M NaCl (isotonic medium), the protein pattern reverted to that of control cells. This protein is mainly localized in the cytosol, although a small part is associated with the 150,000 g pellet and needs detergents to be extracted. The molecular weight and the cellular location suggest a possible analogy with the so-called amphitropic proteins, that are known to interact with both the epidermal growth factor receptor and hydrophobic structures, such as the membrane phospholipids and the cytoskeletal components.

Membrane alterations in G6PD- and PK-deficient erythrocytes exposed to oxidizing agents

After in vitro treatment of normal, glucose-6-phosphate dehydrogenase-deficient or pyruvate kinase-deficient human erythrocytes with three different oxidizing agents, the extent of lipid peroxidative degradation and the alterations of membrane proteins were evaluated. Exposure to tert-butylhydroperoxide induced, most markedly in G6PD- and PK-deficient erythrocytes, a reduction of protein bands 1, 2, 2.1, 3, 4.1, 4.2, and 5, with the appearance of high-molecular-weight aggregates and of "new" polypeptide components in the 29- to 23-kDa region and with a marked increase of membrane-bound globin. Malonyldialdehyde production was highest in G6PD-deficient cells and relatively low in PK-deficient ones. Methylene blue, which had similar but less relevant effects on lipid peroxidation, in G6PD-deficient erythrocytes caused a conspicuous appearance of high-molecular-weight aggregates and a simultaneous relevant decrease of bands 1 and 2 and of membrane-bound globin; it brought about an almost opposite effect in PK-deficient red cells. Acetylphenylhydrazine, which under our conditions appeared the mildest agent, failed, in normal and PK-deficient erythrocytes, to increase malonyldialdehyde production or to alter membrane proteins, whereas it caused, in G6PD-deficient cells, a slight decrease of bands 1 and 2, a more pronounced decrease of band 3, and a marked increase of bands 4.5 and 4.9.

Role of levamisole as immunomodulant in mouse lymphoma model

Levamisole (LMS) has been considered an immunorestorative agent capable of enhancing host's antitumor immune responses. Clinical studies showed that LMS plays a significant role in adjuvant chemotherapy of colorectal cancer. Therefore studies were performed to test whether LMS would be able to restore graft responsiveness in mice with drug-dependent, age-dependent or virus-dependent immunodeficiency. The results show that LMS has little or no influence on the limited antitumor effects of Dacarbazine or Ara-C in mice bearing allogeneic leukemias (i.e. in a host-tumor model in which immuno-chemotherapy synergism occurs with less immunodepressive anticancer drugs). Moreover LMS does not alleviate allograft response inhibition produced by high-dose Dacarbazine or by a mouse RNA virus. However the agent restored graft responsiveness in aged animals. The limited immunoenhancing effects of LMS, as detected in the present study, suggest that the clinical efficacy of the agent could be due to mechanisms not entirely related to its immunopharmacological properties.

A new monoclonal antibody to an age sensitive band 3 transmembrane segment

The appearance of band 3 structural modifications related to aging could be evidenced by means of monoclonal antibodies against senescence antigen. Hence in the attempt to provide an immunological marker of erythrocyte aging, we raised a monoclonal antibody against native band 3 (B6 MoAb), which seems to detect differences in the band 3 molecule from erythrocytes of different ages separated by density gradient. Densitometric evaluation of immunoblotting patterns indicates that the in vivo aging is associated with band 3 monomer degradation. The Percoll separated fractions show a significant increase of those proteolytic fragments that bind the B6 antibody. Finally, protease digestions of unsealed membrane ghosts have been performed to test the binding site of the B6 antibody on the band 3 molecule. The data show that the B6 antibody binds a 19 KDa chymotryptic-tryptic fragment which corresponds to a segment of the looped membrane domain whose steric structure appears to be sensitive to age.

Inhibition of replicative DNA synthesis and induction of DNA repair in human fibroblasts by the intercalating drugs proflavine and 9-aminoacridine

The induction of unscheduled DNA synthesis (UDS) and the alteration of semiconservative DNA replication by the structurally related intercalating agents proflavine and 9-aminoacridine were studied in MRC-5 human fibroblasts in culture. Autoradiographic determinations of both parameters were carried out simultaneously in the same culture specimens. Proflavine affected DNA synthesis, but did not elicit any UDS. 9-Aminoacridine inhibited DNA synthesis only at the highest concentration and caused UDS to a low but significant extent. These results suggest that the ability to induce UDS is not a general property of the intercalating agents and that the alterations of the DNA structure, typical of the "pure" intercalative process, are not handled by pathways involving unscheduled synthesis.

Motor neuron disease in a patient with a monoclonal IgMk directed against GM1, GD1b, and high-molecular-weight neural-specific glycoproteins

In a patient with motor neuron disease and benign IgMk monoclonal gammopathy, the M protein reacted with the glycolipids GM1, GD1b, and asialo GM1 and, by immunoblot, with some high-molecular-weight neural-specific glycoproteins. The main reactive bands had an approximate molecular weight of 250 and 400 kd, were most concentrated in the spinal cord, and were also bound by the lectin peanut agglutinin. The presence of the Ga1(beta 1-3)Ga1NAc epitope on these neural-specific glycoproteins may help to explain the selective neurological impairment of the patient.

Further studies on the gangliosidic nature of the cholinergic-specific antigen, Chol-1

The antigen designated as Chol-1 beta, detected by an antiserum specific for cholinergic neurons, has been purified to homogeneity from ganglioside mixtures extracted from Torpedo electric organ and pig brain. The final products from the two sources behaved identically in a wide range of tests and gave coincident immunopositive and Ehrlich-positive spots after thin layer chromatography in seven different solvent systems; they were thus considered to be identical and to constitute a single, pure chemical species. Gas-chromatographic analysis revealed the presence of long-chain bases, glucose, galactose, N-acetylgalactosamine, and sialic acid in integral molar ratios of 1:1:2:1:3; the compound's reactivity to cholera toxin after Vibrio cholerae sialidase treatment on thin layer chromatography and the recovery of GM1 as sole product of exhaustive sialidase treatment identified it as a member of the gangliotetrahexosyl series. From the products of partial enzymatic desialylation and treatment with beta-galactosidase and a comparison of the compound's immunoreactivity to anti-Chol-1 antisera with that of other trisialogangliosides of defined molecular structure, we were able to assign a disialosyl residue alpha-Neu5Ac-(2----8)-alpha-Neu5Ac-(2----3)- to the inner galactose, and we suggest GalNAc as a possible site of linkage of the third sialic acid.

Hydrolysis of fucosyl-GM1 ganglioside by purified pellet-associated human brain and human liver alpha-L-fucosidases without activator proteins or detergents

Pellet-associated human brain alpha-L-fucosidase was solubilized with 0.5% (w/v) Triton X-100 and purified by affinity chromatography on agarose-6-aminohexanoyl-fucosamine resin. The procedure resulted in a 290,000-fold purification, a 58% yield and a final specific activity of 11,500 nmol/min per mg of protein. Isoelectric focusing indicated that all six major isoforms (with pI values between 4.1 and 5.3) present in crude brain pellet preparations were purified by the affinity technique. SDS/PAGE indicated the presence of one subunit (54 kDa) and a minor protein band at 67 kDa, which presumably is a contaminant since it was not immunoreactive on Western blotting. The pH optimum of the brain enzyme and its apparent Km for the synthetic substrate 4-methylumbelliferyl alpha-L-fucopyranoside were 5.5 and 0.07 mM respectively. Pellet-associated human brain and liver alpha-L-fucosidases were both capable of hydrolysing fucosyl-GM1 ganglioside without activator proteins or detergents. Linear hydrolysis rates were found only for short incubation times (1-5 min). Optimal enzymic activity at 37 degrees C was found at pH 3.4 for both alpha-L-fucosidases, with no activity at pH values above 4.0.

Association to HeLa cells and surface behavior of exogenous gangliosides studied with a fluorescent derivative of GM1

Cultured HeLa cells were incubated with pyrene-GM1/3H-radiolabeled GM1 ganglioside (1:4 M/M) mixtures for various times. The process of association of pyrene-GM1 with cells was qualitatively and quantitatively the same as that of 3H-GM1. The pyrene-GM1 and 3H-GM1 proportions in the various forms of association with cells were similar to that of the starting ganglioside mixture. After 2-h incubation, the association of ganglioside with cells was well established whereas almost no metabolic processing had occurred. During a 24-h incubation, pyrene- and 3H-GM1 underwent similar metabolic processing and gave rise to catabolic (GM2 and GM3) and anabolic (GD1a) derivatives. Fluorescence spectroscopy experiments carried out with the excimer formation technique on subcellular fractions containing plasma membranes showed that exogenous ganglioside was, in part, associated with the cells in a micellar form removable by trypsin treatment, and in part inserted in a seemingly molecular dispersion. Addition of Ca2+ salts caused aggregation of the ganglioside, as indicated by the increase of the excimer:monomer fluorescence ratio. The phenomenon was Ca2+ concentration dependent (maximum at 10 mM), and subsequent addition of EDTA had no effect. The saccharide portion of exogenously incorporated pyrene-GM1 was available to interact with external ligands, as shown by its ability to bind cholera toxin whose addition reduced the collision rate among the ganglioside lipid moieties.

Changes in the ceramide composition of rat forebrain gangliosides with age

Five major gangliosides (GM1, GD1a, GD1b, GT1b, and GQ1b) were extracted and isolated by normal-phase HPLC from the forebrain of Sprague-Dawley rats of ages ranging from 3 days to 24 months. Each ganglioside was fractionated by reverse-phase HPLC into the molecular species carrying a single long-chain base moiety. At all ages, the C18:1 and C20:1 long-chain base species predominated, whereas the C18:0 and C20:0 ones represented 1-3% of the total. The C18:1 long-chain base species, predominant at 3 days (91-96%), diminished with age and reached, at 2 years, 73%, 65%, 61%, 59%, and 45% of the total for GD1a, GM1, GT1b, GD1b, and GQ1b, respectively. The content of the C20:1 long-chain base species, low at birth (4-9%), increased with age in all gangliosides and reached, at 2 years, 27-55% of the total. The developmental behavior of the ganglioside species containing the C18:1 long-chain base was characterized by the following: (a) a biphasic profile with a maximum around 15 days for GD1a, the most abundant ganglioside at all ages; (b) an increase until 6 months for GM1; (c) a sharp decrease until 30 days, followed by leveling for GT1b; and (d) a low, constant level for GD1b and GQ1b. All the ganglioside species containing the C20:1 long-chain base showed a constant increase during development, the increase being more marked in the first 30 days.(ABSTRACT TRUNCATED AT 250 WORDS)

Ultrastructural immunolocalization of laminin and fibronectin in human large intestinal mucosa

The ultrastructural expression of laminin and fibronectin was studied in human colonic mucosa with a pre-embedding immunoperoxidase technique. Both antigens were present in epithelial basement membrane. The lamina densa was uniformly and homogeneously immunostained by both fibronectin and laminin, while the lamina rara showed discrete, positive sites occasionally connecting the lamina densa with the epithelial plasma membrane. In the lamina reticularis, fibronectin was diffusely positive, while laminin showed a discontinuous positivity only in the uppermost region in vicinity of the lamina densa. Collagen fibrils were regularly decorated by fibronectin-positive material. Basement membranes in the capillary wall showed a similar pattern of reactivity both with laminin and fibronectin. These results point out that laminin as well as fibronectin are integral components of intestinal mucosa basement membranes.

Aging and immune response: a multivariate approach

This study on the immune response was chosen as the experimental milieu for the aging process. Parameters associated with the immune response were measured in rats of different ages, thus providing multivariate conditions within which multidimensional data analysis procedures could be applied. These methods, specifically designed for analyzing complex situations, allowed for the delineation of some structural characteristics of maturity and senescence.

Role of vincristine in immunochemotherapy of leukemia in mouse or human models

Synergistic antitumor effects between Vincristine (VCR) and allograft responses have been found in mice bearing allogeneic retrovirus-induced leukemia. In this model VCR depressed weakly allograft reactivity if given before but not after antigen administration. In a parallel human tumor model in vitro using HTLV-1 induced MT-2 leukemia, additive but not synergistic immuno-chemotherapeutic effects were obtained with allogeneic mononuclear cells (MNC) combined with VCR at 0.1 but not at 1 micrograms/ml. In this case natural immunity (NI) rather than antigen-dependent immunity (ADI) was involved in the combined effects of VCR + MNC. In the in vitro model pretreatment of effector cells with 1 or 0.1 micrograms/ml of VCR depressed natural cell-mediated cytotoxicity (NCMC). However when the drug was added to the effector + target cells during the 4 h cytotoxicity assay, 1 but not 0.1 micrograms/ml of the drug was capable of depressing NCMC function. These results would provide valuable information for developing in vitro immuno-chemotherapy studies in human tumor systems, including those characterized by the presence of tumor-associated oncogenic retroviruses, capable of depressing both NI and ADI functions.

Comparison of different computerized classification methods for predicting carcinogenicity from short-term test results

A major obstacle to the use of short-term test results for predicting carcinogenicity is the nonavailability of methods that generate unequivocal estimations of potential carcinogenicity, even in the case of contrasting test results. We compared different mathematical classification methods such as linear discriminant analysis, the K-nearest neighbor rule (KNN), and a new ad hoc classification method called dynamic carcinogenicity assessment (DYCA). The DYCA was developed by us to explicitly reflect the biological results. Through an analysis of a real data base we pointed out the advantages and limitations of these methods. KNN was clearly inferior to the other two algorithms. The novel DYCA approach was more sensitive to carcinogens, whereas linear discriminant analysis proved better for the identification of noncarcinogens.

[Surgical treatment of toxic megacolon in ulcerative rectocolitis. Analysis of 16 patients]

The clinical aspects, surgical treatment and outcome of 16 consecutive patients treated for toxic megacolon secondary to ulcerative colitis at the 1st department of surgery at the university of Rome between 1976 and 1987 were reviewed. The surgical management consisted in total colectomy and immediate ileo-rectal anastomosis, without protective ileostomy in 14 patients and total colectomy with terminal ileostomy and ileorectal anastomosis in 2 patients, 5 months later. No postoperative mortality was observe the immediate complications were: anastomotic leakage, (one case) and rectal bleeding (three cases). The late complications were: ileo-anastomotic stump fistula and perforation (two cases). Protectomy, due to colitis recrudescence, in the rectal remnant 10 months after surgery. These results encourage the total colectomy with immediate ileorectal anastomosis for the treatment of toxic megacolon.

Interrelationships among carcinogenicity, mutagenicity, acute toxicity, and chemical structure in a genotoxicity data base

The interrelationships among carcinogenicity, mutagenicity, acute toxicity (LD50), and a number of molecular descriptors were studied by computerized data analysis methods on the data base generated by the International Program for the Evaluation of Short-Term Tests for Carcinogens (IPESTTC). With the use of statistical regression methods, three main associations were evidenced: (1) the well-known correlation between carcinogenicity and mutagenicity; (2) a correlation between mutagenicity and toxicity (LD50 ip in mice); and (3) a correlation between toxicity and a recently introduced estimator of the free energy of binding of the molecules to biological receptors. As expected on the basis of the large variety of chemical classes represented in the IPESTTC data base, no simple relationship between mutagenicity or carcinogenicity and chemical descriptors was found. To overcome this problem, a new pattern recognition method (REPAD), developed by us for structure-activity studies of noncongeneric chemicals, has been used. This allowed us to highlight a significant difference between the whole patterns of relationships among chemicophysical variables in the two groups of active (mutagenicity and/or carcinogenic) and inactive chemicals. This approach generated a classification rule able to correctly assign about 80% of carcinogens or mutagens.

Ultrastructure of the absorptive cell glycocalyx in hyperplastic colonic polyps after staining with alcian blue and high iron diamine

The glycocalyx of absorptive cells in large intestinal hyperplastic polyp was characterized histochemically at the electron microscope level by the use of the Alcian Blue pH 2.5 and high iron diamine techniques with the aim of comparing their ability in preserving the fine reticular network of the structure. Both the reagents stained glycocalyx, indicating the presence of sulphated acidic glycoconjugates. However, they showed different degrees of condensation of the reactive sites. Alcian Blue preserved its filamentous appearance better.

Structure-activity studies of chemical carcinogens: use of an electrophilic reactivity parameter in a new QSAR model

Electrophilic reactivity data for 142 compounds were obtained from the literature, and were used to establish the contribution of different functional groups and molecular determinants to this property. An equation containing approximately 20 molecular determinants was derived (r = 0.89); this provided a system for estimating the electrophilic reactivity for other compounds on the basis of their molecular structure. The contribution of the estimated electrophilicity to the structure-activity relationship (SAR) studies of carcinogens was tested. In a previous work, we studied a set of 137 carcinogens and non-carcinogens belonging to different chemical classes, and established an SAR on the basis of four physical-chemical descriptors. The mathematical model consisted of a pattern recognition method specifically designed by us for the non linear situations typical of large non congeneric sets of chemicals. The addition of the estimated electrophilicity parameter increased the overall performance of the system (from the previous 85-90% retrospective correct classification). In particular, the estimated electrophilicity remarkably contributed to the identification of carcinogens (their correct classification increasing from the previous 86% to 97%). The derived SAR was tested by applying it to 11 human carcinogens not included in the training set. Their carcinogenicity was correctly predicted for 10 chemicals out of 11.

Evaluation of postoperative blood coagulation changes in elderly patients undergoing major surgery

18 elderly patients submitted to major surgery for malignancies or other disease were studied to assess the relationship between changes of blood coagulation factors and inhibitors in the early post-operative period and the appearance of lower limb deep vein thrombosis. A decrease in serum antithrombin III (AT III) Protein C antigen (PC: Ag) and Plasminogen activity (PLG) levels from the second to the fourth postoperative day, together with a simultaneous increase in serum fibrinogen (FG) and von Willebrand Factor (vWF:Ag) antigen levels was observed. In 8 patients, PC:Ag levels dropped below the limit considered at risk to develop DVT (less than 60 U/dl). A patient with the lowest PC:Ag levels had deep vein thrombosis From the analysis of data it was concluded that in the postoperative period, blood coagulation changes occur in elderly patients, predisposing to the risk of deep vein thrombosis.

Changes of immunological patterns of human cancer cells treated in vitro with a triazene compound

Previous experimental evidence indicates that immunogenicity of mouse tumor cells can be increased by treatment with dacarbazine and other triazene compounds. The present studies have been conducted on the human cell lines H125 (lung cancer), 1246 (melanoma), X3 (EBV-immortalized B cells) subjected to in vitro treatment with 4 (3-methyl-1-triazeno) benzoic acid potassium salt (MTBA). Untreated or drug-treated sublines were tested for susceptibility to allogeneic NK effector cells, either non-stimulated or pretreated with beta-Interferon. In the case of X3 cell line and its MTBA-treated subline the expression of the EBV-associated antigens and the capability of eliciting autologous cytotoxic T lymphocytes (CTL) were also investigated. The results suggest that a modification of membrane antigenic pattern could be induced by MTBA treatment in terms of changes of cell susceptibility to cell-mediated lysis, expression of EBV-related antigens and capability to elicit autologous CTL.

Maternal adrenalectomy and adult offspring in a conflict situation in the rat

The effects of the absence of maternal adrenals during pregnancy (P), during lactation (L), during pregnancy and lactation (PL) were studied on pain suppressed behavior (punished drinking test) of the adult offspring in comparison with controls (C). The female L offspring showed a lower responsiveness to the anxiogenic stimulus, as demonstrated by increased water intake, decreased percentage of ineffective licks, and decreased time to perform 300 licks compared to C. The male L behavior was not affected. Reduced growth was not responsible for the reduced anxiogenic reactivity because also both male and female PL offspring had lower weight than C, but did not show any significant effect. Pain threshold in the tail flick test was the same in all types of offspring. Thus, absence of maternal adrenals, specifically during lactation, significantly affects behavior of female offspring. It is discussed whether this is due to the lack of a physiological influence of maternal adrenal hormones on brain ontogenesis (hippocampal glucocorticoid receptors), or on the development of the brain-pituitary-adrenal system during neonatal life of the offspring.

Predicting carcinogenicity with short-term tests: biological models and operational approaches

This paper illustrates the basic biological models that have had an influence on the development and deployment of short-term assays for carcinogens. A tentative description of such a conceptual framework is provided with the use of methods for the quantitative analysis of information. This picture is contrasted with the results of a series of statistical mathematical analyses carried out on real genotoxicity data bases. The resulting evidence indicates that the biological models derived from basic laboratory research are not adequate or sufficient to interpret the operational performances of short-term assays. Obviously these models are of great importance, but, this observed discrepancy suggests the need for articulated approaches, with particular emphasis on analytical tools able to interpret the complexity of these systems. In particular, the multivariate data analysis methods are indicated as suitable for the description of large and complex bodies of data, and the identification of typologies and regularities. A number of applications of such methods are also presented. The conclusion is that biological models and operational approaches have to interact on the same level. The operational approach should indicate whether the conceptual framework of the experimenter is adequate to describe the experimental situation and possibly point to new relationships and trends, as well as to practical solutions.

Computer-assisted analysis of interlaboratory Ames test variability

The interlaboratory Ames test variability of the Salmonella/microsome assay was studied by comparing 12 sets of results generated in the frame of the International Program for the Evaluation of Short-Term Tests for Carcinogens (IPESTTC). The strategy for the simultaneous analysis of test performance similarities over the whole range of chemicals involved the use of multivariate data analysis methods. The various sets of Ames test data were contrasted both against each other and against a selection of other IPESTTC tests. These tests were chosen as representing a wide range of different patterns of response to the chemicals. This approach allowed us both to estimate the absolute extent of the interlaboratory variability of the Ames test, and to contrast its range of variability with the overall spread of test responses. Ten of the 12 laboratories showed a high degree of experimental reproducibility; two laboratories generated clearly differentiated results, probably related to differences in the protocol of metabolic activation. The analysis also indicated that assays such as Escherichia coli WP2 and chromosomal aberrations in Chinese hamster ovary cells generated sets of results within the variability range of Salmonella; in this sense they were not complementary to Salmonella.

Increase of natural killer activity of mouse lymphocytes following in vitro and in vivo treatment with lithium

The in vivo and in vitro influence of lithium lactate on mouse natural killer activity was investigated. In vitro exposure of effector-target mixture to graded concentrations of lithium did not substantially modify the natural killer activity of mouse splenocytes, untreated or pretreated with cyclophosphamide. However in vitro treatment of effector splenocytes increased the frequency of NK-percursor cells. The in vivo treatment with lithium lactate greatly increased the natural killer activity in intact mice, whereas it did not improve this cytotoxic function in host immunodepressed by cyclophosphamide. These data suggest that lithium salts produce a modulation of natural killer activity of mouse spleen cells, probably through a mechanism involving the increase of the number of NK-precursors in hosts not subjected to cytotoxic chemotherapy.

Statistical exploration of four major genotoxicity data bases: an overview

This report puts into perspective a series of exploratory statistical analyses carried out on the major genotoxicity data bases. While large compilations of data, even though computerized, suffer from their own size and are quite intractable to scientific reflection and judgement, the multivariate data analysis methods used by us are specifically designed for reorganising the information in a rational way and highlighting the underlying regularities of the data. The analyses reported here refer to the following data bases: the International Program for the Evaluation of Short-Term Tests for Carcinogens, the International Program on Chemical Safety Collaborative Study on In Vitro Assays, the Gene-Tox data base, and a subset of the U.S. National Toxicology Program data. Although the various data bases consisted of different sets of chemicals and had different underlying rationales, a number of invariant associations among short-term test performances were highlighted. The overall evidence indicated that the traditional classification of assays (according to the criteria of genetic end-point and phylogenetic position of the assays) was in contrast with the actual, operational similarities among assay performances, in that the experimental responses of the tests to the large variety of chemicals under consideration pointed to an alternative classification scheme. This consisted of three major classes: 1) a class comprising the in vivo assays; 2) a class grouping together many of the most widely used in vitro assays (Salmonella, chromosomal aberrations, and sister chromatid exchanges in Chinese hamster ovary cells, the various mutation tests in mammalian cell systems, etc.); 3) a second in vitro assay class (with Syrian hamster embryo cell transformation, Saccharomyces cerevisiae XV185-14C, B. subtilis rec-, Escherichia coli pol A). Such classes had clearly differentiated features with respect to carcinogenicity prediction. The implications of these findings for the current debate on mutagenicity testing are discussed.

Influence of cetylpyridinium chloride on the ultrastructural appearance of sulphated glycosaminoglycans in human colonic mucosa

The effect of adding cetylpyridinium chloride to the fixative on the preservation of sulphated glycosaminoglycans (SGs) was studied in human normal colonic mucosa. SGs were visualized at the ultrastructural level through the application of Spicer's High Iron Diamine (HID) technique followed by a post-fixation with potassium ferrocyanide-reduced osmium tetroxide. SGs were mainly localized in basement membranes of epithelium and capillary wall and along collagen fibers. The morphology of the reactive sites depended on the presence of cetylpyridinium chloride, SGs being granular in absence of the salt and more or less elongated when cetylpyridinium chloride was added to the fixative. We suggest that the use of cetylpyridinium chloride during fixation may help to preserve SG molecule at the ultrastructural level.

Combined effects of immunity and antitumor drugs against cancer. I. In vivo studies with cis-diamminedichloroplatinum and cyclophosphamide in mouse models

Cis-diamminedichloroplatinum (DDP) or cyclophosphamide (Cy) were given to mice bearing L1210 or LSTRA leukemia in H-2 compatible tumor-host combinations. Little anti-tumor activity was afforded by DDP against both leukemias inoculated in entirely histocompatible recipients. However, when the drug was given to mice incompatible for minor histocompatibility loci (MMHL) with the tumor, the efficacy of the treatment was markedly augmented and a substantial number of long-term survivors was found among BALB/c mice inoculated with L1210 cells. On the other hand, no difference in survival times was found between histocompatible or allogeneic mice inoculated with both leukemias, not subjected to chemotherapy. The LSTRA model was much less susceptible to this type of DDP-mediated antineoplastic immuno-chemotherapy synergism. Moreover no synergistic effects with allograft reaction were detected with Cy in both L1210 and LSTRA models, although Cy was markedly more active than DDP against leukemic cells in histocompatible recipients.

Combined effects of immunity and antitumor drugs against cancer. II. In vitro studies with cis-diamminedichloroplatinum in a human leukemia system

Human K562 leukemic cells were exposed in vitro to cis-diamminedichloroplatinum (DDP) followed by addition of intact or irradiated mononuclear cells (MNC) obtained from peripheral blood of normal donors. tumor inhibition provoked by DDP was significantly enhanced by normal MNC, but not by irradiated cells at the effector: leukemic cell ratio of 2:1. In contrast MNC alone did not show appreciable effects on K562 cells. The NK activity of MNC was also inhibited by exposure to gamma rays. The combined effects of DDP + MNC do not appear to be due to increased susceptibility of DDP-pretreated K562 cells to NK-mediated cytolysis. Actually leukemic cells treated with 10 micrograms/ml of DDP and cultured for 48 h at 37 degrees C, showed decline of susceptibility to the cytotoxic effects of MNC. These studies suggest that natural immunity could be of potential value in the clinical use of DDP.

Protein kinase C mediates human neutrophil cytotoxicity

Human neutrophils stimulated with phorbol myristate acetate were able to damage human erythroleukemic K562 cells, in the absence of specific antibody, as assessed by a two hour 51Cr release assay. Neutrophils treated with formyl-peptide fMet-Leu-Phe did not display tumoricidal response, but the addition of diacylglycerol kinase inhibitor R59022 together with formyl-peptide induced the cytotoxic capacity against tumor target cells. Phorbol ester is a potent activator of certain functions of neutrophils because of its ability to directly and irreversibly stimulate protein kinase C; formyl-peptide, on the contrary, activates protein kinase C by inducing a rapid and transient production of diacylglycerol, that is quickly metabolized. The addition of an inhibitor of diacylglycerol kinase, R59022, however potentiated the action of formyl-peptide. These results indicate that protein kinase C is involved in the tumoricidal activity of neutrophils against K562 cells, and that maximal activation of the enzyme is required to achieve the cytotoxic response.

Isolation and purification of a major allergen from Parietaria officinalis pollen

A major allergen of Parietaria officinalis, a species responsible for a large number of respiratory allergies in Mediterranean areas, has been identified and characterized. This allergen (Pol) was found in the fraction which precipitates between 70 and 100% ammonium sulphate saturation. Pol showed a molecular weight of 15,000 daltons as determined by SDS-PAGE and HPLC. The pI of Pol was in the pH region 4-6, IEF showing four major bands. Two major bands were shown by CIE, CRIE and immunoblotting; major contaminants or aggregates were also revealed by the latter technique and by HPLC. Pol showed an allergic specific activity 2 times higher than the crude extract; moreover it was shown to be a major allergen since it inhibited 29 out of 30 sera from allergic patients sensitive to P. officinalis.

The conceptual framework of monitoring mutagens/carcinogens: a critical appraisal

The main theme of this paper is an analysis of the present knowledge and conceptual framework in the field of monitoring for carcinogenic and mutagenic agents. The conclusions of the International Symposium on "Monitoring human exposure to carcinogenic and mutagenic agents" (Helsinki, 1983) were taken as a starting point for a series of considerations; methods suitable for the quantitative treatment of the information were applied to evidence the profile of current research in this area. The analysis indicated that the major underlying paradigms were related to technical considerations, such as chemical specificity, precision, reproducibility or ease of execution, as well as to the concept of mechanism of action of genotoxic agents. On the other hand, the lack of reliable information about the operational relevance of the systems for assessing health effects was dramatically evidenced. As a conclusion, the dangers of relying on a scientific background derived only from the basic research, without a critical re-examination in terms of real, operational performances of the systems, are emphasized.

Which rules for assembling short-term test batteries to predict carcinogenicity?

The main theme of this paper is to describe the basic requirements for assembling reliable batteries of short-term tests for carcinogenicity prediction. For this purpose, a subset of the data base generated by the International Program for Evaluation of Short-Term Tests for Carcinogens (IPESTTC) has been studied by different data-analysis methods. Much attention has been focused on the methodological dimensions of the problem, at the level of selection of both data and statistical techniques. Twenty-one of the most widely used short-term assays were considered. An exploratory study of the data base was first performed by factor analysis, showing similarities and dissimilarities between test performances and confirming our previous results obtained by cluster analysis. In this way the assays were divided into three groups on the basis of their responses to the chemicals. The Salmonella assay was in the central group, characterized by equilibrated performances in respect to sensitivity and specificity for carcinogens. Tests complementary to the Salmonella assay for sensitivity and specificity, respectively, were identified as well. A preliminary comparison of the IPESTTC results with the Gene-Tox data base is also presented. The test performances in respect to carcinogenicity prediction were then evaluated by discriminant analysis. When the subset of data was considered as a whole, the procedure resulted in a linear discriminant function able to correctly identify 84.2% of carcinogens and 83.3% of noncarcinogens. The correctly identified carcinogens summed to about 90% when adequate batteries of tests were used. This analysis yielded a number of observations. (1) Together with the selectivity indices (such as sensitivity and specificity), the operational complementarity between test performances must be ascertained and taken into account. (2) The batteries most effective at predicting carcinogenic activity were composed of three tests, one for each group. This finding converged with the fact that the three classes of assays were clearly differentiated for sensitivity and specificity, and in this sense were complementary to each other. (3) The performances of the batteries were not improved by adding more tests, but in several cases the opposite effect occurred. (4) Estimation of the probability of the chemicals of being carcinogenic, starting from qualitative genotoxicity data, is possible.

New chemical trends in ganglioside research

A report is given of recent progress in the methodology for isolation of gangliosides from natural sources, for the preparation of molecular species of gangliosides homogeneous in both the oligosaccharide and ceramide portions of the molecule, for chemical manipulation and derivatization of gangliosides, and for the preparation of gangliosides radiolabelled in different parts of the molecule. Particular emphasis has been given to: high performance liquid chromatographic procedures capable to separate gangliosides on the basis of their oligosaccharide or ceramide moieties and yielding completely homogeneous compounds, that is gangliosides with a single oligosaccharide, a single long chain base and a single fatty acid; two-dimensional thin-layer chromatographic procedures, provided with a fully computerized quantification system, particularly suitable to identifying gangliosides containing alkali-labile linkages, including ganglioside lactones; chemical procedures of high yield for reducing gangliosides at the double bond of long chain base, for selective removal of the fatty acyl moiety and replacement with a novel fatty acid, and for the synthesis of ganglioside lactones; chemical procedures for inserting fluorescent, paramagnetic or photoreactive probes at the fatty acyl part of the ganglioside molecule; procedures for chemical isotopic radiolabelling of gangliosides at the level of sialic acid acetyl group and at the fatty acid moiety. Examples are provided evidencing the significance and potential use of a variety of ganglioside derivatives in the study of ganglioside metabolism and functional implications.

Influence of interferon on the functional expression of natural killer target structures of murine lymphoma cells

Murine lymphoma cells (YAC-1), induced by Moloney leukemia virus, nontreated (YAC) or pretreated in vitro with interferon (YAC-IF), were tested for their susceptibility to natural killer (NK)-mediated cytolysis. In line with previous reports YAC-IF were less susceptible to NK lysis than YAC cells. In cold competition assay, YAC-IF inhibited cytotoxicity to a lesser extent than YAC lymphoma when labeled target YAC cells were used. However, when radioactive YAC-IF cells were used as targets, cold competition attained with both YAC and YAC-IF was essentially the same. Furthermore, effector splenocytes, depleted of NK effector cells through immunoabsorption on YAC monolayer, were inactive against both YAC and YAC-IF targets. On the other hand, effector lymphocytes, absorbed on YAC-IF monolayer, retained NK activity against YAC cells but not against YAC-IF targets. These results are compatible with the hypothesis that interferon (IF) modulates negatively a subset of "interferon-susceptible" (IFS) NK target structure(s) (TS) of YAC cells, which would then express membrane determinants not functionally present on YAC-IF cells. On the other hand YAC and YAC-IF cells share "interferon-resistant" (IFR) TS not affected by pretreatment with IF. In order to test whether IFS X TS and IFR X TS are present on the same cell or clonally distributed, YAC cells were cloned and tested for NK susceptibility following IF pretreatment. The results did not support the hypothesis of a clonal distribution of both IFS X TS and IFR X TS since IF pretreatment of all clones, obtained by limiting dilution, resulted in a net impairment of target susceptibility to NK effector cells.

A new insight into chemical mutagenesis by multivariate data analysis

Computerized data analysis was applied to a genotoxicity data base, consisting of 42 chemicals assayed in 20 short-term mutagenicity tests. Factor and cluster analysis were used to elicit underlying patterns and to classify the chemicals in groups homogeneous for the kind of genetic damage induced. This analysis put in light a clear differentiation between effects in in vivo and in vitro systems, while the heuristic value of the traditional categories (such as point-mutation and chromosomal damage, or prokariotic and eukariotic systems) was not confirmed.