HPLC-MS/MS-based quantification of human monoclonal antibodies targeting SARS-CoV-2 in the presence of endogenous SARS-CoV-2 antibodies in human serum.

Antibodies for treatment and prophylaxis against SARS-CoV-2 are needed particularly for immunocompromised individuals, who cannot adequately benefit from vaccination. To address this need, Aerium Therapeutics is developing antibodies targeting the SARS-CoV-2 spike protein. A bioanalytical method to quantify fully human monoclonal antibodies in a population with widely varying anti-spike antibody titers is required to investigate the pharmacokinetics of these antibodies in clinical trials.

First Steps Towards an Understanding of a Mode ofCarcinogenic Action for Vanadium Pentoxide.

Inhalation of vanadium pentoxide clearly increases the incidence of alveolar/bronchiolar neoplasms in male and female B6C3F1 mice at all concentrations tested (1, 2 or 4 mg/m(3)), whereas responses in F344/N rats was, at most, ambiguous. While vanadium pentoxide is mutagenic in vitro and possibly in vivo in mice, this does not explain the species or site specificity of the neoplastic response. A nose-only inhalation study was conducted in female B6C3F1 mice (0, 0.

Preclinical 28-day inhalation toxicity assessment of s-nitrosoglutathione in beagle dogs and Wistar rats.

To support clinical development of S-nitrosoglutathione (GSNO) as a therapeutic agent, 28-day toxicology studies in rats and dogs were conducted. Rats (21-25/sex) and dogs (3-5/sex) were exposed for 4 hours or 1 hour, respectively, to inhaled GSNO (0, 3, 9.3, 19, and 28 mg/kg per d in rats and 0, 4.

Genotoxicity assessment of the antiepileptic drug AMP397, an Ames-positive aromatic nitro compound.

AMP397 is a novel antiepileptic agent and the first competitive AMPA antagonist with high receptor affinity, good in vivo potency, and oral activity. AMP397 has a structural alert (aromatic nitro group) and was mutagenic in Salmonella typhimurium strains TA97a, TA98 and TA100 without S9, but negative in the nitroreductase-deficient strains TA98NR and TA100NR. The amino derivative of AMP397 was negative in wild-type strains TA98 and TA100.

4-chloro-o-phenylenediamine induces a dose-related increase in G:C > T:A transversions and one major DNA adduct in the liver of Big Blue mice after 26 weeks in feed treatment.

The monocyclic aromatic amine 4-chloro-o-phenylenediamine (4-C-o-PDA), a known mutagen and mouse hepatocarcinogen, was tested for its in vivo mutagenic potential in the Big Blue transgenic mouse assay system. Genomic DNA was isolated from liver tissue of control and treated animals and lacI mutants were recovered. In an initial 2-week study 4-C-o-PDA was administered daily per os to groups of male and female C57BL/6 Big Blue mice at doses of 0 and 200 mg/kg for 2 weeks (on working days) followed by a treatment free expression time of 10 days.

Comparative analysis of 8-oxo-2' -deoxyguanosine in DNA by 32P- and 33P-postlabeling and electrochemical detection.

8-Oxo-2'-deoxyguanosine (8-oxo-dG) is emerging as a useful marker for oxidative DNA damage. Reported basal levels determined by 32P-postlabeling (PPL) method were 10-fold or more higher than those obtained with HPLC/electrochemical detection (ECD). This discrepancy was investigated.

Determination of dichlorobenzidine-hemoglobin adducts by GC/MS-NCI.

A method based on gas chromatography/mass spectrometry-negative ion chemical ionization detection (GC/MS-NCI) was developed for the determination of 3,3'-dichlorobenzidine (DCB)-hemoglobin adducts. Adducts were released from hemoglobin by mild alkaline hydrolysis and determined by GC/MS-NCI after extraction and derivatization with heptafluorobutyric anhydride (HFBA). 2,2'-DCB was used as internal standard and the recovery of the diarylamine derivatives in the overall procedure was 65-88%.

Synthesis and quantification of DNA adducts of 4,4'-methylenedianiline.

4,4'-Methylenedianiline (MDA) is used as a hardener in the manufacture of plastics and polyurethanes. MDA has been classified as a carcinogen in animals and is a suspected human carcinogen. Assuming that MDA would yield similar DNA adducts to other arylamines, we synthesized the following C-8 guanine adducts: N'-acetyl-N-(deoxyguanosin-8-yl)-MDA, N-(deoxyguanosin-8-yl)-MDA, N-(deoxyguanosin-8-yl)-4MA, and their corresponding 3'-monophosphate derivatives.

Lack of bioavailability of dichlorobenzidine form diarylide azo pigments: molecular dosimetry for hemoglobin and DNA adducts.

The hypothetical release of 3,3'-dichlorobenzidine (DCB) from two insoluble azo pigments and from a soluble azo dye was investigated in female Wistar rats for a 4 week treatment with 0.2% (w/w) Colour Index Pigment 13 (PY13) or 0.2% (w/w) Colour Index Pigment Yellow 17 (PY17) in the diet or 0.

Bromopropylate: induction of hepatic cytochromes P450 and absence of covalent binding to DNA in mouse liver.

Oral administration of benzilic acid ester-based acaricide bromopropylate at daily doses of 3, 15, 100, and 300 mg/kg body wt to young adult male Tif:MAGf mice for 14 days caused slightly increased liver weights in the high-dose group. A dose-dependent increase of the microsomal cytochrome P450 content was accompanied by elevated ethoxycoumarin O-deethylase, ethoxyresorufin O-deethylase, pentoxyresorufin O-depentylase, and total testosterone hydroxylase activities. When compared with mice treated in parallel with the model compounds for hepatic xenobiotic metabolizing enzyme induction, phenobarbitone, and 3-methylcholanthrene, the enzyme activity changes observed with bromopropylate largely equalled those expressed in phenobarbitone-treated mice.

Molecular dosimetry of DNA adducts in C3H mice treated with bisphenol A diglycidylether.

The formation of a glycidaldehyde-DNA adduct in skin of C3H mice treated with [14C]bisphenol A diglycidylether has been previously reported and it was assumed that the modification occurred on guanine residues. We were interested in elucidating the structure of this glycidaldehyde-DNA adduct by using a non-radioactive approach. Male C3H mice were treated with a single topical dose of 2 mg bisphenol A diglycidylether in acetone for 48, 96 or 192 h.

Studies on the mechanism of induction of microsomal cytochrome P452 and peroxisomal bifunctional enzyme mRNAs by nafenopin in primary cultures of adult rat hepatocytes.

The amount of the two mRNAs although lower in cultured hepatocytes than in freshly isolated cells was found to be rapidly inducible upon the addition of 32 microM nafenopin. The induction of cyt.P452 mRNA always preceded the induction of PBE mRNA, but for both, the maximal induction (10-20-fold over control) was obtained within 24 hr and was achieved by transcriptional activation.

No measurable increase in thymidine glycol or 8-hydroxydeoxyguanosine in liver DNA of rats treated with nafenopin or choline-devoid low-methionine diet.

Male rats were treated for 2 months with 1000 ppm nafenopin in the diet or for 4 or 7 days with a choline-devoid low-methionine diet. DNA was isolated from the livers and analyzed for the presence of cis-thymidine glycol-3'-phosphate (cis-dTGp) by 32P-postlabeling and for the level of 8-hydroxy-deoxyguanosine (8-OH-dG) by electrochemical detection (ECD). In no DNA sample was the level of cis-dTGp above the limit of detection of 1 modified thymidine per 10(6) nucleotides.

Lack of covalent binding to DNA of di-n-octyltin dichloride (DOTC) in vivo and in vitro.

[14C]Di-n-octyltin dichloride ([14C]DOTC) was administered by oral gavage to male and female rats. After 96 h hepatic and thymic DNA was isolated. All DNA fractions were radioactive, but analysis of DNA hydrolysates by HPLC revealed that the radioactivity was incorporated via biosynthesis and was not due to adduct formation.

The significance of in vitro studies on peroxisome proliferation.

Peroxisome proliferation in rodents is associated with hepatocarcinogenicity. This association has led to increased interest in the phenomenon and to the search for in vitro tests to detect peroxisome proliferators and to study the mechanisms by which proliferation occurs. Primary cultures of adult rat hepatocytes provide such a system: peroxisomal enzymes, cytochrome P-452 and replicative DNA synthesis may all be induced and the response to treatment with many peroxisome proliferators is observed in a manner similar to that in the liver in vivo.

Hydrolysis of bisphenol A diglycidylether by epoxide hydrolases in cytosolic and microsomal fractions of mouse liver and skin: inhibition by bis epoxycyclopentylether and the effects upon the covalent binding to mouse skin DNA.

Synergistic interactions have been reported in the carcinogenicity of two epoxy resin components to mouse skin. A mixture of bisphenol A diglycidylether and bis epoxycyclopentylether was highly carcinogenic, despite the fact that neither compound gave positive results when applied individually. To elucidate the mechanism of this synergistic interaction we have investigated the effects of bis epoxycyclopentylether upon the hydrolysis and DNA-binding of bisphenol A diglycidylether.

Detection by 32P-postlabeling of thymidine glycol in gamma-irradiated DNA.

The 32P-postlabeling method has been adapted for the analysis of thymidine-cis-glycol-3'-phosphate (cis-dTGp,cis-5,6-dihydroxy-5,6-dihydrothymidine-3'-phosphat e). Cis-dTGp was isolated and purified from normal nucleotides by phenylboronate affinity chromatography and phosphorylated by T4 polynucleotide kinase in presence of 1 mM BeCl2 at pH 7.5.

DNA methylation in rat liver by daminozide, 1,1-dimethylhydrazine, and dimethylnitrosamine.

[methyl-14C]Daminozide (succinic acid 2',2'-dimethylhydrazide; 37 mg/kg), 1,1-[14C]dimethylhydrazine (UDMH; 19 mg/kg), and [14C]dimethylnitrosamine (DMNA; 0.1 mg/kg) were administered by oral gavage to male Sprague-Dawley rats. After 24 hr, the animals were killed and DNA was purified from the livers to constant specific radioactivity.

Trenbolone growth promotant: covalent DNA binding in rat liver and in Salmonella typhimurium, and mutagenicity in the Ames test.

DNA binding in vivo: [6,7-3H]beta-trenbolone (beta-TBOH) was administered p.o. and i.

Potency of carcinogens derived from covalent DNA binding and stimulation of DNA synthesis in rat liver.

In order to investigate the role of the stimulation of cell division for the initiation (and possibly promotion) of liver tumors by chemical carcinogens, the incorporation of radiolabelled thymidine into liver DNA was determined in male rats. Single doses of various levels of aflatoxin B1, benzidine and carbon tetrachloride (all known to be genotoxic via DNA binding) did not affect cell division, whereas several hepatocarcinogens known not to bind to DNA (alpha-HCH, clofibrate, and 2,3,7,8-tetrachlorodibenzo-p-dioxin) gave rise to a dose-dependent stimulation of liver DNA synthesis within 24 h. An equation combining the influences of mitotic stimulation, expressed as dose required to double the control level of DNA synthesis, and DNA binding potency, expressed as the Covalent Binding Index, correlated well with the carcinogenic potency for both classes of hepatocarcinogens.

The relevance of covalent binding to mouse liver DNA to the carcinogenic action of hexachlorocyclohexane isomers.

[3H]Hexachlorocyclohexane (HCH) was synthesized by chlorination of [3H]benzene prepared by catalytic tritiation of benzene with tritiated water. The isomers of HCH were separated by adsorption chromatography on silica gel. In order to determine the covalent binding to DNA, [3H]HCH was administered to male mice by oral gavage, and liver DNA was isolated via chromatin.

In vivo covalent binding of aflatoxin B1 and aflatoxin M1 to liver DNA of rat, mouse and pig.

[14C]Aflatoxin B1 (AFB1) was isolated from cultures of Aspergillus parasiticus grown on [1-14C]sodium acetate. Covalent binding of AFB1 to liver DNA of rat and mouse was determined 6-8 h after oral administration. The effectiveness of covalent binding, expressed as DNA binding per dose in the units of a 'Covalent Binding Index' (CBI), (micromol aflatoxin/mol DNA nucleotides)/(mmol aflatoxin/kg animal), was found to be 10 400 for rats and 240 for mice.