Werner Schloot

A cross-sectional study of self-reported chemical-related sensitivity is associated with gene variants of drug-metabolizing enzymes

BackgroundN-acetyltransferases (NAT) and glutathione S-transferases (GST) are involved in the metabolism of several ubiquitous chemical substances leading to the activation and detoxification of carcinogenic heterocyclic and aromatic amines. Since polymorphisms within these genes are described to influence the metabolism of ubiquitous chemicals, we conducted the present study to determine if individuals with self-reported chemical-related sensitivity differed from controls without self-reported chemical-related sensitivity with regard to the distribution of genotype frequencies of NAT2, GSTM1, GSTT1, and GSTP1 polymorphisms.MethodsOut of 800 subjects who answered a questionnaire of ten items with regard to their severity of chemical sensitivity 521 unrelated individuals agreed to participate in the study. Subsequently, genetic variants of the NAT2, GSTM1, GSTT1, and GSTP1 genes were analyzed.ResultsThe results show significant differences between individuals with and without self-reported chemical-related sensitivity with regard to the distribution of NAT2, GSTM1, and GSTT1 gene variants. Cases with self-reported chemical-related sensitivity were significantly more frequently NAT2 slow acetylators (controlled OR = 1.81, 95% CI = 1.27–2.59, P = 0.001). GSTM1 and GSTT1 genes were significantly more often homozygously deleted in those individuals reporting sensitivity to chemicals compared to controls (GSTM1: controlled OR 2.08, 95% CI = 1.46–2.96, P = 0.0001; GSTT1: controlled OR = 2.80, 95% CI = 1.65–4.75, P = 0.0001). Effects for GSTP1 gene variants were observed in conjunction with GSTM1, GSTT1 and NAT2 gene.ConclusionThe results from our study population show that individuals being slow acetylators and/or harbouring a homozygous GSTM1 and/or GSTT1 deletion reported chemical-related hypersensitivity more frequently.

Further evidence for nonrandom chromosome changes in carcinoma cells--a report of 28 cases.

A cytogenetic study was made of pleural and ascitic effusions from 28 carcinoma patients. Gross chromosome abnormalities were observed in each case. A selection against heteroploid cells occurred generally in long-term cell cultures. Although no further evidence for the existence of primary specific chromosome abnormalities was found in this study, we postulate three types of chromosome abnormalities in carcinoma cells: (a) primary, specific chromosome changes; (b) secondary, but nonrandom, chromosome changes; and (c) random chromosome changes. We feel that it may be a feature of the secondary changes to cause high mitotic instability, which leads to further karyotype variability, new changes of type b and c, and an increased potential for malignancy.

Structural rearrangements of chromosome Nr 8 involving 8q12--a primary event in pleomorphic ademona of the parotid gland.

Nine pleomorphic adenomas of the human parotid gland were investigated. Within this series the group of cases having clonal aberrations of chromosome Nr 8 predominates. The occurrence of cases with trisomy-8 and cases with structural rearrangements involving a breakpoint in 8q11-8q13 allows a further subdivision of this group of tumors. Our special interest in this paper is devoted to the latter group. the hypothesis is proposed that in these cases the chromosomal rearrangement is the primary event in tumorigenesis, leading to activation of a so far unknown oncogene located most likely at 8q12. The translocations to different recipient chromosomes may serve as sign posts to transcriptionally active chromosomal domains in the salivary gland.

Genotyping of the polymorphic N‐acetyltransferase (NAT2) and loss of heterozygosity in bladder cancer patients

Acetylation is one of the major routes in metabolism and detoxification of a large number of drugs, chemicals and carcinogens. Slow acetylators are said to be more susceptible to developing bladder cancer and because of investigations about tumor risk based on phenotyping procedures, it was our aim to study the distribution of allelic constellations of the N‐acetyltransferase (NAT2) by genotyping patients with bladder cancer. We analysed NAT2 gene of blood and tumor DNA from 60 patients with primary bladder cancer and DNA of blood samples from 154 healthy individuals. Using ASO‐PCR/RFLP techniques we identified 70% of patients with bladder cancer (n = 42) to be slow acetylators while genotyping of controls resulted in 61% with slow acetylators (n = 94). In addition, dividing bladder cancer patients in males and females the genotype NAT2 * 5B/NAT2 * 6A occured with much higher frequencies in males (OR = 4, 95%; CI = 1.8–8.9).

Gender-specific effects of NAT2 and GSTM1 in bladder cancer.

One approach for risk assessment of cancer is the evaluation of polymorphic enzymes involved in cancer using molecular tools. Phase II enzymes are involved in the detoxification of several drugs, environmental substances and carcinogenic compounds. Here, we analyzed enzymes for their putative relevance in urinary bladder cancer. The hereditable enzyme polymorphism of arylamine N‐acetyltransferase 2 (NAT2) and glutathione S‐transferase M1 (GSTM1) and T1 (GSTT1) was studied in 157 hospital‐based patients and in 223 control subjects. Slow acetylation was not observed to be a significant risk factor of developing bladder cancer (OR: 1.33; 95% CI 0.85–2.09). One genotype responsible for slow acetylation (NAT2*5B/*6A) was observed significantly more frequently in bladder cancer patients compared with control subjects (OR: 1.63; 95% CI 1.03–2.58). 
Gender‐specific effects were observed when patients were divided into subgroups. In male patients, slow acetylators were identified as carrying a significant increased risk of developing bladder cancer, in particular when the genotype NAT2*5B/*6A was combined with the GSTM1 null genotype (OR: 4.39; 95% CI 1.98–9.74). By contrast, the same genotype combination significantly protected female patients from bladder cancer (OR: 0.21; 95% CI 0.06–0.80).

No rearrangement of c-mos in salivary gland pleomorphic adenomas with 8q12 aberrations.

The frequent occurrence of salivary gland pleomorphic adenomas characterized by clonal structural chromosome abnormalities involving 8q12 raises the question as to how the cytogenetic rearrangements correspond to molecular mechanisms of tumor development. Since the proto-oncogene c-mos maps to this breakpoint region, DNA from eight adenomas with these aberrations was isolated and checked for rearrangements of c-mos after digestion by BamHI, EcoRI and HindIII. In none of the tumors was a rearranged allele besides the germ-line fragments found.

Pleomorphic adenomas with unbalanced chromosomal abnormalities have an increased in vitro lifetime.

The in vitro lifetime of 100 salivary gland pleomorphic adenomas was investigated. On the average, they had a limited lifetime of 3.7 passages. In 86 cases, the tumors were successfully karyotyped, resulting in three major cytogenetic subgroups characterized by either an apparently normal karyotype or by rearrangements of 8q12 or 12q13-15. There was no significant difference between the in vitro lifetime of the tumors with a normal or with an aberrant karyotype. The three adenomas with the longest lifetime were characterized by an unbalanced karyotype. One of them had a deleted chromosome 6, which has also been described in malignant tumors. An increased in vitro lifetime may thus correspond to early steps of malignant transformation in vivo and can be caused by additional unbalanced chromosome aberrations. In the future, long-term cultivation can be helpful in defining chromosomal regions involved in this process.

A rapid and simple Sandwich-Method used for chromosome analysis from small fetal and adult biopsy specimens

A new Sandwich‐Method is described which uses aborted material and yields a high frequency of metaphases. Chromosome studies may be performed after 7–8 days without sub‐culturing. It is possible to freeze the original tissue for later cell culture.

Acetylation of procainamide and isoniazio by a rat liver-N-acetyl-transferase

SummaryThe genetic variation of the enzyme isoniazid-N-acetyltransferase has been studied in man and other species. Homogenates of liver samples of adult LEW rats also acetylate procainamide. The kinetic properties of isoniazid and procainamide acetylation are similar and are consistent with a ping-pong Bi-Bi mechanism. The experimental data support the hypothesis that one acetyltransferase catalyses both procainamide and isoniazid. Furthermore, a simple spectrophotometric assay to determine procainamide acetylation is presented.

The Molecular Oncology of 12q13–15

Since the observation of alterations in the same cytogenetical breakpoint region 12q13–15 in a group of solid human tumors, the relationship between the breakpoints and the chromosomal localization of oncogenes or suppressor genes has been of particular interest. In this region, four oncogenes (sas, mdm-2, wnt-1, gli) and two putative suppressor genes (rap1B, CHOP) have been localized (Fig. 1). The main results obtained concerning the function of these genes during normal development and their implications for tumorigenesis will be discussed in this chapter.