Comparison of the metabolism of 10 chemicals in human and pig skin explants.

Skin metabolism is important to consider when assessing local toxicity and/or penetration of chemicals and their metabolites. If human skin supply is limited, pig skin can be used as an alternative. To identify any species differences, we have investigated the metabolism of 10 chemicals in a pig and human skin explant model. Phase I metabolic pathways in skin from both species included those known to occur via cytochrome P450s, esterases, alcohol dehydrogenases and aldehyde dehydrogenases. Common Phase II pathways were glucuronidation and sulfation but other conjugation pathways were also identified. Chemicals not metabolized by pig skin (caffeine, IQ and 4-chloroaniline) were also not metabolized by human skin. Six chemicals metabolized by pig skin were metabolized to a similar extent (percentage parent remaining) by human skin. Human skin metabolites were also detected in pig skin incubations, except for one unidentified minor vanillin metabolite. Three cinnamyl alcohol metabolites were unique to pig skin but represented minor metabolites. There were notable species differences in the relative amounts of common metabolites. The difference in the abundance of the sulfate conjugates of resorcinol and 4-amino-3-nitrophenol was in accordance with the known lack of aryl sulfotransferase activity in pigs. In conclusion, while qualitative comparisons of metabolic profiles were consistent between pig and human skin, there were some quantitative differences in the percentage of metabolites formed. This preliminary assessment suggests that pig skin is metabolically competent and could be a useful tool for evaluating potential first-pass metabolism before testing in human-derived tissues.

The investigation of a class of capacitated arc routing problems: the collection of garbage in developing countries.

The collection, transport and disposal of solid waste, which is a highly visible and important municipal service, involves a large expenditure but receives, scant attention. This problem is even more crucial for large cities in developing countries due to the hot weather. A constructive heuristic which takes into account the environmental aspect as well as the cost is proposed to solve the routing aspect of garbage collection. This is based on a look-ahead strategy which is enhanced by two additional mechanisms. Interesting results were obtained when tested on instances with and without the presence of the effect of the environment.

Viral haemorrhagic septicaemia virus induces vig-2, a new interferon-responsive gene in rainbow trout.

An mRNA differential display methodology was used to study the rainbow trout response to viral infection. A new transcript (vig-2) induced by viral haemorrhagic septicaemia virus (VHSV) in rainbow trout leucocytes was identified from the head-kidney. vig-2 was also induced in vivo during experimental infection and following DNA immunisation with a plasmid containing a gene encoding the viral glycoprotein. Viral induction of vig-2 was blocked by cycloheximide (CHX), indicating its dependency on a newly synthesised intermediate protein. This intermediate protein is most probably related to interferon because treatment of cells with a conditioned medium displaying an interferon-like activity resulted in a strong vig-2 expression, which was not blocked by CHX treatment. The cDNA sequence of the vig-2 transcript displays several mRNA destabilisation motifs and two signals characteristic of immediate-early gene expression. Curiously, vig-2 has no evident encoding potential except for a small 51 amino acid putative polypeptide with no clear similarity to any sequence available in the databanks. Therefore, the complete vig-2 genomic sequence was determined from a lambda phage clone retrieved from a genomic DNA library of rainbow trout. The genomic organisation of vig-2 shows five exons delimited with typical splice acceptor and donor sites. A promoter with a canonical ISRE, confirming that vig-2 is an interferon-responsive gene, is also present 115 nt upstream of the first exon.

Identification of a cellular protein specifically interacting with the precursor of the hepatitis B e antigen.

In hepatitis B virus (HBV) the precore gene encodes a protein from which derives P22, the precursor of the mature secreted hepatitis B virus e antigen (HBeAg). Circumstantial evidences suggest that HBeAg and/or its precursor P22 are important for establishing persistent infection. Although P22 is essentially present in the secretory pathway, a substantial fraction has been found in the cytosol. In order to get new insights into the biological function of P22, we looked for cellular proteins which could strongly associate with this protein. Using immunoprecipitation studies on human cell extracts, we found that a non-secreted cellular protein of about 32 kDa (P32) bound with a high specificity to P22. P32 associated neither with HBeAg nor with the viral core protein P21 which exhibits the same amino acids sequence as P22 but is N-terminally shorter by 10 residues. We also demonstrated that this interaction depended on the presence of the P22 C-terminal domain. Our data argues for a potential biological function of P22.

Spontaneous monoclonal immunoglobulin-secreting peripheral blood mononuclear cells as a marker of disease severity in multiple myeloma.

Peripheral blood from patients with multiple myeloma (MM) contains a small number of plasma cells related to the bone marrow tumour cells by their cytoplasmic immunoglobulin (Ig), their cell membrane antigen expression and/or their gene rearrangements, but hitherto the monoclonal Ig (M-Ig) production by circulating cells has not been reported. Using a two-colour ELISPOT assay, Ig-secreting cells (Ig-SCs) were detected in the blood of 28 MM and five Waldenstrom's macroglobulinaemia (WM) patients. The number of cells that spontaneously produced an Ig isotype similar to that of the M-Ig in serum was greater than that of the other Ig-SCs. MM patients presented an excess of circulating heavy-chain (alpha or gamma) Ig-SCs (0.38% of the PBMC) with kappa or lambda light chains (0.48%) compared with the number of cells secreting the other heavy- (0.02%) and light-chain isotypes (0.03%). WM patients also presented high numbers of cells secreting the mu-heavy-chain isotype (0.66%). The Ig synthesized in vitro was characterized as monoclonal, and the M-Ig secretory capacity of the peripheral blood cells was similar to that observed for Ig-SCs from polyclonal activated B cells in vivo. The number of these monoclonal cells was significantly increased in patients in an advanced stage of MM (I/II vs. III, P < 0.001) and correlated with the serum beta-2 microglobulin concentration (r = 0. 69; P < 0.0003). The number of M-Ig-SCs in MM patients could be a useful marker for evaluating the progression of multiple myeloma.

Distribution of the amatoxins and phallotoxins in Amanita phalloides. Influence of the tissues and the collection site.

The toxin composition of 25 Amanita phalloides carpophores collected from three sites in Franche-Comté (France) differing in their geological and pedological characteristics was determined and the factors involved in the variations of the toxin concentration in the tissues were identified. The concentrations of the main amatoxins (beta-amanitin, alpha-amanitin, gamma-amanitin) and phallotoxins (phallacidin, phallisacin, phalloidin, phallisin, phalloin) in the six tissues constituting the carpophore, i.e. the cap (C), gills (G), ring (R), stipe (S), bulb (B) and volva (V) were evaluated by using high-performance liquid chromatography. The results analysed statistically showed that the toxin concentrations were tissue dependent, leading to classification of the tissues into two groups (B, V) and (C, G, R, S). The (B, V) group was distinguished by high amounts of phalloidin, phallisin and phallisacin, and the (C, G, R, S) group by the predominance of the amatoxins. The characteristics of the soil of the collection site also affected the toxin concentrations; however, this effect differed from one site to another and was not similar for all the tissues. Finally, the mean toxin profile in the carpophores from the three sites was evaluated. This study underscores the fact that environmental factors and mainly the soil type clearly have an effect on the toxin composition of A. phalloides carpophores.

A new approach for clinical biological assay comparison and standardization: application of principal component analysis to a multicenter study of twenty-one carcinoembryonic antigen immunoassay kits.

BACKGROUND: Principal component analysis (PCA) is a powerful mathematical method able to analyze data sets containing a large number of variables. To our knowledge, this method is applied here for the first time in the field of medical laboratory analysis. METHODS: PCA was used to evaluate the results of a blind comparative study of 21 carcinoembryonic antigen (CEA) reagent kits used to determine CEA concentration in a panel of sera from 80 patients. RESULTS: The mathematical technique first eliminated the variations attributable to the use of different calibrators. The PCA representation then gave a global view of the dispersion of the kits and allowed the identification of a main homogeneous group and of some discrepant kits. CONCLUSIONS: PCA applied to the in vitro diagnostic reagent field could contribute to the standardization process and improve the quality of medical laboratory analyses. A standardization method using a panel of patient sera is proposed.

Development and standardization of an immuno-quantified solid phase assay for HIV-1 aspartyl protease activity and its application to the evaluation of inhibitors.

The catELISA technique was modified and standardized for measuring HIV-1 aspartyl protease activity and evaluating the potency of synthetic peptide inhibitors. This immuno-quantified solid phase assay combines the use of an immobilized C-terminal biotinylated peptide as substrate, a crude enzyme preparation, and a highly specific antiserum elicited against the C-terminal product of the enzyme reaction. A standard curve of this C-terminal product was constructed to determine the enzyme activity. This assay, which requires less enzyme and substrate, is more sensitive than the conventional HPLC method. The amounts of C-terminal peptide produced in solution as determined from ELISA and HPLC standard curves were comparable. Analogues of peptidomimetics designed in our laboratory were assayed for their potency to inhibit the enzyme. One of them, H4, which is a hydroxyethylamine isostere of the Phe-Pro peptide bond, was a powerful inhibitor.

CD4 masking during human immunodeficiency virus type 1 infection, quantified on peripheral blood lymphocytes, is a potential marker of disease progression.

In human immunodeficiency virus type 1 (HIV-1)-infected adults, the proportion of gp120-free CD4 molecules on the surface of T lymphocytes was measured by double-epitope EIA and expressed as a CD epitope concentration ratio. In 51% of these patients (n=81), CD4 T cells showed a significant decrease (up to 100%) in the accessibility of the CD4 epitope in the D1 domain remained accessible. Of interest, a significant increase in the CD4 gp120 binding site concentration, without a change in T cell counts, was observed within 10 days after initiation of zidovudine treatment. Furthermore, CD4 masking by gp120 was associated with a poor clinical patient status. The assessment of the CD4 epitope concentration ratio is proposed as a surrogate marker of disease progression in HIV-1-infected patients.

An efficient immunization protocol for production of monoclonal antibodies against soluble human insulin.

A new immunization protocol has been developed to obtain specific monoclonal antibodies (mAb) directed against the soluble form of human insulin. Various protocols differing on the basis of the nature of immunogen, the number of injections and the route of administration of the antigen were compared. Mice with the highest anti-insulin titers were selected for cell fusion. The results showed that the immunization protocol involving 2 injections of insulin followed by a boost 2 months later mainly stimulated B lymphocytes secreting IgM mAb directed against immobilized insulin. Immunization with 2 injections of human proinsulin followed by 2 injections of a human insulin-bovine serum albumin conjugate and finally with a booster injection of this conjugate on each of the last 4 days preceding fusion was necessary to obtain a high percentage of hybridomas secreting specific IgG mAb able to recognize immobilized insulin (indirect ELISA) as well as iodinated insulin (liquid-phase radioimmunoassay).

Autoimmunity to human thyroglobulin. Respective epitopic specificity patterns of anti-human thyroglobulin autoantibodies in patients with Sjögren's syndrome and patients with Hashimoto's thyroiditis.

We evaluated the epitopic specificity pattern of anti-human thyroglobulin (anti-hTg) autoantibodies from patients with primary Sjögren's syndrome (SS). All of the primary SS sera tested contained both IgG and IgM anti-hTg autoantibodies recognizing at least 1 region on hTg; in 65% of the cases, 3 or more regions were recognized. A strong recognition of region II, as is seen in Hashimoto's thyroiditis, was associated with thyroid disorder in primary SS. These results emphasize the importance of region II in autoimmune thyroid disease.

The DNA polymerase from the archaebacterium Sulfolobus acidocaldarius: a thermophilic and thermoresistant enzyme which can perform automated polymerase chain reaction.

A DNA polymerase purified from the thermoacidophilic archaebacterium Sulfolobus acidocaldarius was used to perform automated DNA amplification at 70 degrees C as well as site directed mutagenesis by Polymerase Chain Reaction (P.C.R.). The yield of amplification performed at optimum MgCl2 concentration for the Taq or the S. acidocaldarius DNA polymerase, for the same DNA target, was equivalent. The ability of S. acidocaldarius DNA polymerase to perform P.C.R. under less stringent requirement of MgCl2 concentration gives this enzyme a non-negligible advantage over the Taq DNA polymerase.

An anti-Cryptococcus neoformans monoclonal antibody directed against galactoxylomannan.

Six monoclonal antibodies (mAb) were produced by immunizing mice with a Cryptococcus neoformans serotype A spheroplast lysate (CNSL). Two mAb were of the IgG1 isotype; the others were IgM. The results obtained with one IgM mAb (CN6) are reported herein. This mAb recognized the four serotypes of C. neoformans and no cross-reactions were observed with extracts from Cryptococcus melibiosum, Candida albicans, Saccharomyces cerevisiae, Torulopsis glabrata or Trichosporon beigelii. Fractionation of the CNSL by gel filtration revealed that mAb CN6 recognized high molecular weight substances as well as a range of smaller molecules. Indirect ELISA inhibition studies showed that this mAb recognized substances in a cryptococcal culture filtrate. Inhibition studies and agglutination tests using latex beads sensitized with purified CN6 showed that CN6 strongly reacted with the C. neoformans serotype A cell envelope galactoxylomannan-mannoprotein complex (GAlXM-MP) and only weakly with the glucuronoxylomannan (GXM) component. These tests also showed that purified galactoxylomannan (GalXM) from C. neoformans serotype A was more reactive than purified mannoprotein (MP). An anti-GalXM mAb might be a useful tool for monitoring the clinical course of cryptococcal infections.

Biosynthesis of hepatitis B virus e antigen: directed mutagenesis of the putative aspartyl protease site.

The C gene products of all mammalian hepadnaviruses contain a region with sequence similarities to the catalytic center of the aspartyl proteases. This region could have the capacity to cleave precore proteins, leading to the synthesis of e antigen. By site-directed mutagenesis on a plasmid containing the hepatitis B virus C gene, we have replaced either the Asp residue of the putative aspartyl protease catalytic center or an Asp residue located 3 amino acids upstream. Transient expression of the mutated hepatitis B virus C gene in human and mouse cells showed that none of these mutations prevented the secretion of an accurately processed HBe antigen. Thus, we demonstrated that the aspartyl protease responsible for e antigen precursor processing is not C gene encoded but is more likely to be a cellular enzyme. From these results, we suggest a model for the mechanism of e antigen synthesis.

DNA polymerase from Sulfolobus acidocaldarius. Replication at high temperature of long stretches of single-stranded DNA.

The activity of a homogeneous DNA polymerase from the thermophilic archaebacterium, Sulfolobus acidocaldarius, on a singly primed, single-stranded recombinant phage M13 DNA has been examined. At the optimal temperature (70 to 75 degrees C) this template is efficiently replicated in ten minutes using a ratio of enzyme molecule to primed-template of 0.8. Analysis of DNA products during the course of polymerization shows that species of quite homogeneous size are observed and that the number of primers extended by the enzyme is constant, whatever the enzyme molecule to primed template ratio is in the range 1/50 to 2, indicating that the 100 x 10(3) Mr DNA polymerase from S. acidocaldarius is randomly recycled on the template molecules. At non-optimal temperature (60 degrees C and 80 degrees C) the distribution of products observed indicated the presence of arrest sequences; some have been shown to be reversible. One of these pausing signals detected at 80 degrees C has been further analysed, and has been found to be DNA sequence-dependent.

A DNA polymerase from a thermoacidophilic archaebacterium: evolutionary and technological interests.

The archaebacteria constitute a group of prokaryotes with an intermediate phylogenetic position between eukaryotes and eubacteria. The study of their DNA polymerases may provide valuable information about putative evolutionary relationships between prokaryotic and eukaryotic DNA polymerases. As a first step towards this goal, we have purified to near homogeneity a DNA polymerase from the thermoacidophilic archaebacterium Sulfolobus acidocaldarius. This enzyme is a monomeric protein of 100 kDa which can catalyze DNA synthesis using either activated calf thymus DNA or oligonucleotide-primed single-stranded DNA as a template. The activity is optimal at 70 degrees C and the enzyme is thermostable up to 80 degrees C; however, it can still polymerize up to 200 nucleotides at 100 degrees C. These remarkable thermophilic properties and thermostability permit examination of the mechanism of DNA synthesis under conditions of decreased stability of the DNA helix. Furthermore, these properties make S. acidocaldarius DNA polymerase a very efficient enzyme to be used in DNA amplification by the recently developed polymerase chain reaction method (PCR) as well as in the Sanger DNA sequencing technique.

Antigenic domains on the human thyroglobulin molecule recognized by autoantibodies in patients' sera and by natural autoantibodies isolated from the sera of healthy subjects.

We determined the regions on the human thyroglobulin (hTg) molecule recognized by anti-hTg autoantibodies (aAbs) in the sera of patients with Hashimoto's thyroiditis, Graves' disease, and thyroid carcinoma and by anti-hTg natural aAbs isolated from the sera of healthy subjects. Fifteen anti-hTg monoclonal antibodies (MAbs) directed against six distinct antigenic regions were used for this study. The anti-hTg aAbs in the patients' sera recognized mainly region II and occasionally region IV. The natural aAbs were present in the serum at low concentrations; consequently, we isolated and concentrated them for this investigation. The isolated natural aAbs inhibited the interaction of the anti-hTg MAbs with the majority of the antigenic regions identified. Region II was not well recognized, however, by these natural aAbs. This difference in specificity between the anti-hTg aAbs and the anti-hTg natural aAbs may have diagnostic significance.

Production and characterization of highly specific anti-methotrexate monoclonal antibodies.

Spleen cells of a Biozzi HR mouse immunized with a bovine serum albumin-methotrexate conjugate were fused with P3-X63-Ag8.653 mouse myeloma cells. Twenty-three monoclonal antibodies (MAbs), selected by indirect ELISA, were produced and partially characterized. Using methotrexate (MTX) and eight structurally related compounds, binding specificities of the MAbs were assessed by inhibition enzyme immunoassay. All the MAbs had very low affinity for folic acid and its analogs and for the major MTX metabolite 7-hydroxymethotrexate. Using a computer cluster analysis program based on the binding specificities, the MAbs were divided into three groups. The thirteen MAbs in group I recognized primarily the pteridine portion of the MTX molecule; the eight group II MAbs recognized the benzene ring as well as the pteridine structure. The two MAbs in group III poorly distinguished between the different parts of the MTX molecule. The apparent equilibrium association constants of the anti-MTX MAbs in groups I, II, and III ranged from 7 x 10(9) to 3 x 10(8) M-1 (except for 1 MAb), from 5 x 10(7) to 6 x 10(6) M-1 (except for 2 MAbs), and from 1 x 10(6) to 3.5 x 10(5) M-1, respectively.