Search PubMed⌕ Search

Biomedical subjects

A Hofmann

Publications and source records attributed to A Hofmann.

At least 73 records · Page 4Linked to original sources
PubMed1997

Dissection of the gene of the bifunctional PGK-TIM fusion protein from the hyperthermophilic bacterium Thermotoga maritima: design and characterization of the separate triosephosphate isomerase.

Triosephosphate isomerase (TIM), from the hyperthermophilic bacterium Thermotoga maritima, has been shown to be covalently linked to phosphoglycerate kinase (PGK) forming a bifunctional fusion protein with TIM as the C-terminal portion of the subunits of the tetrameric protein (Schurig et al., EMBO J 14:442-451, 1995). To study the effect of the anomalous state of association on the structure, stability, and function of Thermotoga TIM, the isolated enzyme was cloned and expressed in Escherichia coli, and compared with its wild-type structure in the PGK-TIM fusion protein. After introducing a start codon at the beginning of the tpi open reading frame, the gene was expressed in E.c.BL21(DE3)/ pNBTIM. The nucleotide sequence was confirmed and the protein purified as a functional dimer of 56.5 kDa molecular mass. Spectral analysis, using absorption, fluorescence emission, near- and far-UV circular dichroism spectroscopy were used to compare the separated Thermotoga enzyme with its homologs from mesophiles. The catalytic properties of the enzyme at approximately 80 degrees C are similar to those of its mesophilic counterparts at their respective physiological temperatures, in accordance with the idea that under in vivo conditions enzymes occupy corresponding states. As taken from chaotropic and thermal denaturation transitions, the separated enzyme exhibits high intrinsic stability, with a half-concentration of guanidinium-chloride at 3.8 M, and a denaturation half-time at 80 degrees C of 2 h. Comparing the properties of the TIM portion of the PGK-TIM fusion protein with those of the isolated recombinant TIM, it is found that the fusion of the two enzymes not only enhances the intrinsic stability of TIM but also its catalytic efficiency.

Bacterial Proteins↗
PubMed1997

Death of solid tumor cells induced by Fas ligand expressing primary myoblasts.

Anticancer therapy for solid tumors suffers from inadequate methods for the localized administration of cytotoxic agents. Fas ligand (FasL) has been reported to be cytotoxic to a variety of cells, including certain tumor cell lines. We therefore postulated that myoblasts could serve as non-transformed gene therapy vehicles for the continuous localized delivery of cytotoxic anticancer agents such as FasL. However, contrary to previous reports, fluorescence activated cell sorting (FACS) analyses revealed that both primary mouse and human myoblasts express Fas, the receptor for FasL. To avoid self-destruction and test the cytotoxic potential of myoblasts, the cells were isolated from mice deficient in Fas (lpr/lpr), the mouse counterpart of human autoimmune lymphoproliferative syndrome (ALPS). These primary mouse myoblasts were transduced with a retroviral vector encoding mouse FasL and expression of a biologically active and soluble form of the molecule was confirmed by the apoptotic demise of cocultured Fas-expressing Jurkat cells, the standard in the field. To test whether the lpr myoblasts expressing FasL could be used in anticancer therapy, human rhabdomyosarcoma derived cell lines were assayed for Fas and then tested in the apoptosis coculture assay. The majority of Fas-expressing muscle tumor cells were rapidly killed. Moreover, FasL expressing myoblasts were remarkably potent; indeed well characterized cytotoxic antibodies to Fas were only 20% as efficient at killing rhabdomyosarcoma cells as FasL expressing myoblasts. These findings together with previous findings suggest that primary myoblasts, defective in Fas but genetically engineered to express FasL, could function as potent anticancer agents for use in the localized destruction of solid tumors in vivo by three synergistic mechanisms: (1) directly via Fas/FasL mediated apoptosis, (2) indirectly via neutrophil infiltration and immunodestruction, and (3) as allogeneic inducers of a bystander effect via B and T cells.

Animals↗
PubMed1997

In vitro and in vivo effects of SCA40 on guinea pig airways.

SCA40 (6-bromo-8-methylaminoimidazo [1,2-a]-pyrazine-2-carbonitrile), a compound which had been described as an opener of Ca(2+)-dependent large conductance potassium channels (BKCa channels), was investigated in comparison with salbutamol for in vitro and in vivo bronchospasmolytic effects and for the ability to reverse airways hyperreactivity in guinea pigs. SCA40 reduced the spontaneous tone of isolated guinea pig tracheal rings with a biphasic concentration-response curve (first phase: pD2 = 8.0, EMax = 29.7% of maximal effect; second phase: pD2 = 6.4, EMax = 72.6%). The salbutamol curve was monophasic (pD2 = 8.0, EMax = 100%). Total lung resistance (RL) was determined in anaesthetized, ventilated guinea pigs. Bronchoconstriction, measured as an increase in RL, was elicited in normoreactive animals by i.v. infusion of bombesin (100 ng/kg/min) or by i.v. injection of histamine (1.8-5.6 micrograms/kg). Airways hyperreactivity was induced by acute i.v. administration of pre-formed immune complexes. Intravenous bolus injections of histamine (2.4 micrograms/kg) were used to define the sensitivity of the airways prior to and after the exposure to immune complex. Following intratracheal (i.t.) administration, SCA40 reversed bombesin-induced bronchoconstriction with an ED50 of 43 micrograms/kg (EMax = 57%). The ED50 for salbutamol was 0.8 microgram/kg i.t. (EMax = 78%). Histamine-induced bronchoconstriction in hyperreactive guinea pigs was inhibited by SCA40 with an ED50 of 13 micrograms/ kg i.t. (EMax = 82%). Salbutamol completely inhibited histamine-induced bronchospasm with an ED50 of 9 ng/kg i.t. In normoreactive guinea pigs, SCA40 prevented histamine-induced bronchoconstriction with an ED50 of 100 micrograms/kg i.t.; for salbutamol the ED50 in this test was 0.48 microgram/kg i.t. Thus, for both SCA40 and salbutamol, the effects obtained at low doses in hyperreactive guinea pigs represent a true reversal of airways hyperreactivity, whereas at higher doses, anti-hyperreactive and bronchospasmolytic properties may account for the observed effects. In conclusion, SCA40 relaxes guinea pig airways smooth muscle in vitro and in vivo, and it partly reverses airways hyperreactivity. With respect to both potency and efficacy, SCA40 is markedly less active than the beta-adrenoceptor agonist salbutamol.

Albuterol↗
PubMed1997

Drug specific antibodies: T-cell epitope-lipopeptide conjugates are potent adjuvants for small antigens in vivo and in vitro.

To generate conventional or monoclonal antibodies for the serological detection of drugs, antibiotics, toxins and other low molecular mass substances, a suitable and effective adjuvant is needed. Lipopeptides derived from a major component of the bacterial cell wall constitute potent nontoxic and nonpyrogenic immunoadjuvants when mixed with conventional antigens. Here we demonstrate that the synthetic lipopeptide N-palmitoyl-S-[2,3-bis(palmitoyloxy)-(2R,S)-propyl]-(R)-cysteinyl- serine (P3CS) coupled to a Th-cell epitope (P3CS-Th) can efficiently enhance the specific immune response against low molecular weight compounds in different species. In the presence of the synthetic lipopeptide P3CS-Th, the peptides which are per se non-immunogenic stimulated a specific humoral immune response in mice after intraperitoneal application. Mixtures containing adjuvants without the Th sequence showed no significant antibody induction. A marked enhancement of the humoral immune response was obtained with the low molecular mass antigens Iturin AL, Herbicolin A and Microcystin (MLR) coupled to poly-l-lysin (MLR-PLL), in rabbits and in chickens. Lipopeptide-Th cell epitope conjugates also constituted adjuvants for the in vitro immunization of either human mononuclear cells or mouse B-cells with MLR-PLL; after fusion of the immunized cultures with the heteromyeloma cell lines CB-F7 or the mouse myeloma cell line SP 2/0, respectively, we observed a significantly increased yield of antibody secreting hybridomas.

Adjuvants, Immunologic↗
PubMed1997

Human thyroid carcinoma cell lines and normal thyrocytes: expression and regulation of matrix metalloproteinase-1 and tissue matrix metalloproteinase inhibitor-1 messenger-RNA and protein.

Matrix metalloproteinase-1 (MMP-1) and tissue matrix metalloproteinase inhibitor 1 (TIMP-1) play an important role in remodeling the extracellular matrix in normal and pathological processes. The effect of phorbol-myristate acetate (PMA), interleukin-1 (IL-1), and tumor necrosis factor-alpha (TNF-alpha) on MMP-1 and TIMP-1 expression was studied on highly purified thyrocytes and undifferentiated 8505 C, C 643, HTh 74, SW 1736 thyroid carcinoma cells compared with thyroid-derived fibroblasts. Messenger RNA (mRNA) levels were monitored by competitive semiquantitative reverse transcriptase polymerase chain reaction (RT-PCR) after 24 hours. Culture supernatants were assayed for free and/or complexed MMP-1 and TIMP-1 after 48 hours using enzyme-linked immunosorbent assay (ELISA) systems (detection limit: <2 ng/mL). MMP-1 and TIMP-1 mRNA were present in all cell types, although thyrocytes showed MMP-1 mRNA levels near the detection limit. 8505 C expressed MMP-1 mRNA levels of up to 10(6) times those of the other cells analyzed. PMA and IL-1 increased MMP-1 mRNA in most cell types. TIMP-1 mRNA increased after treatment with PMA in all cells except 8505 C, whereas only slight effects were shown after IL-1 stimulation. MMP-1 protein was undetectable in normal thyrocyte cultures, but was secreted spontaneously by all cell lines ([ng/mL]; C 643: 15+/-7; HTh 74: 81+/-1; SW 1736: 13+/-2; 8505 C: 2097+/-320). There was a strong correlation between levels of MMP-1 mRNA and protein (r = 0.99, p < .0001). PMA and IL-1 increased MMP-1 secretion in all cell types after 48 hours. Fibroblasts ([ng/mL] 517+/-55) and the cell lines (C 643: 142+/-48; HTh 74: 115+/-13; SW 1736: 202+/-14; 8505C: 120+/-19) secreted TIMP-1 in unstimulated cultures, whereas only a trace amount was detected in thyrocyte cultures, even after PMA treatment. IL-1 upregulated TIMP-1 secretion after 48 hours in SW 1736, HTh 74, and C 643 cells. Our data suggest that in contrast to normal thyrocytes, dedifferentiated thyroid carcinoma cell lines are potential producers of MMP-1 as well as TIMP-1. High MMP-1 or MMP-1/TIMP-1 expression may play a role in tissue invasion of undifferentiated thyroid cancer cells.

Adult↗
PubMed1997

Diversity of the vif gene of human immunodeficiency virus type 1 in Uganda.

Little sequence information is available for human immunodeficiency virus type 1 (HIV-1) vif genes of African origin. Here we describe 37 new complete vif genes of 18 AIDS patients from Uganda and show that vif has a high in vivo genetic variability. vif proviral DNA sequences of peripheral blood cells were determined by direct sequencing of PCR products. Only 52% of the deduced Vif amino acids were absolutely conserved; when Vif sequences previously analysed were considered, only 32% of the Vif consensus sequence comprised conserved and as such possibly functionally important motifs. The high inter-individual vif variability was in contrast to a very low intra-individual variability. One patient carried a vif gene with a stable C-terminal deletion, but N-terminal truncations were not found in patients' predominant vif sequences. The vif genes analysed comprised subtypes A, D and an A/D mosaic. Phylogenetic analyses additionally showed that HIV- 1 in Uganda has spread across the boundaries of ethnic groups.

Acquired Immunodeficiency Syndrome↗
PubMed1996

The structure of recombinant human annexin VI in crystals and membrane-bound.

The crystal structure of calcium-free recombinant human annexin VI was solved at a resolution of 3.2 A by using the annexin I model for Patterson search and refined to an R-factor of 19.0%. The molecule consists of two similar halves closely resembling annexin I connected by an alpha-helical segment and arranged perpendicular to each other. The calcium and membrane binding sites assigned by structural homology are therefore not located in the same plane. Analysis of the membrane-bound form of annexin VI by electron microscopy shows the two halves of the molecule coplanar with the membrane, but oriented differently to the crystal structure and suggesting a flexible arrangement. Ion channel activity has been found for annexin VI and the half molecules by electrophysiological experiments.

Annexin A6↗
PubMed1996

Rapid retroviral delivery of tetracycline-inducible genes in a single autoregulatory cassette.

We describe a single autoregulatory cassette that allows reversible induction of transgene expression in response to tetracycline (tet). This cassette contains all of the necessary components previously described by others on two separate plasmids that are introduced sequentially over a period of months [Gossen, M. & Bujard, H. (1992) Proc. Natl. Acad. Sci. USA 89, 5547-5551]. The cassette is introduced using a retrovirus, allowing transfer into cell types that are difficult to transfect. Thus, populations of thousands of cells, rather than a few clones, can be isolated and characterized within weeks. To avoid potential interference of the strong retroviral long terminal repeat enhancer and promoter elements with the function of the tet-regulated cytomegalovirus minimal promoter, the vector is self-inactivating, eliminating transcription from the long terminal repeat after infection of target cells. Tandem tet operator sequences and the cytomegalovirus minimal promoter drive expression of a bicistronic mRNA, leading to transcription of the gene of interest (lacZ) and the internal ribosome entry site controlled transactivator (Tet repressor-VP16 fusion protein). In the absence of tet, there is a progressive increase in transactivator by means of an autoregulatory loop, whereas in the presence of tet, gene expression is prevented. Northern blot, biochemical, and single cell analyses have all shown that the construct yields low basal levels of gene expression and induction of one to two orders of magnitude. Thus, the current cassette of the retroviral construct (SIN-RetroTet vector) allows rapid delivery of inducible genes and should have broad applications to cultured cells, transgenic animals, and gene therapy.

Animals↗
PubMed1996

Structural and functional characterisation of the voltage sensor in the ion channel human annexin V.

The ion channel properties of human annexin V, a calcium- and phospholipid-binding protein of the annexin family, have been structurally and functionally investigated by analysing the mutant Glu112 -->Gly. Glu112 forms a salt bridge with Arg271 located in the interior of the hydrophilic pore of the molecule which is conserved within the annexin family. The crystal structures of the mutant and wild-type proteins are very similar and show only marginal conformational changes around the mutation site. Electron microscopic images show a conserved four-domain structure upon membrane binding as in the wild-type annexin V. The channel properties of the mutant are drastically changed, as the mutant has lost the voltage-dependent channel gating and the selectivity for calcium ions over monovalent cations. These results strongly support the hypothesis that the central, hydrophilic pore is the ion-conducting pathway.

Annexin A5↗
PubMed1996

The crystal structure and ion channel activity of human annexin II, a peripheral membrane protein.

Annexin II binds in a calcium-dependent manner to acidic phospholipids and is a substrate of some protein kinases. An N-terminally shortened form of human annexin II was crystallized and its molecular structure determined. It is very similar to two previously described members of this protein family, annexin I and annexin V. The protein structure is nearly completely alpha-helical organized as four compact domains which consist of five alpha-helices each. The domains surround a hydrophilic pore. The calcium binding sites are located at the convex side of the structure as in annexin V. Recombinant and natural porcine annexin II are active as ion channel with characteristics similar to annexin V, while N-terminally shortened annexin II and the heterotetramer (annexin II-p11)2 are inactive. Two cysteine residues, Cys133 and Cys262, form a disulphide bridge connecting domains II and III, adding further weight to the notion that ion channel activity does not require major structural rearrangements.

Amino Acid Sequence↗
PubMed1996

Expression of tumour necrosis factor-alpha (TNF-alpha) mRNA and protein in pathological thyroid tissue and carcinoma cell lines.

There has been much controversy about the presence of TNF-alpha within thyroid tissue. We therefore conducted a study to determine if TNF-alpha mRNA is present in thyroid tissue and thyroid-derived cells. Semiquantitative reverse transcriptase-polymerase chain reaction (RT-PCR) was employed with a heterologous competitor fragment. Significantly lower levels of TNF-alpha mRNA were found in the autonomous nodules from patients with thyroid autonomy (TA; n = 4; 5.7 +/- 1.3 arbitrary units (AU) (mean +/- s.e.m.); P < 0.03) and in normal thyroid tissue (n = 2, 7.0 +/- 3.1 AU) compared with tissue from patients with Graves' disease (GD; n = 13; 27.9 +/- 10.3 AU), non-toxic multinodular goitre (NTG; n = 5; 20.9 +/- 5.8 AU) and perinodular tissue from TA patients (20.3 +/- 4.0 AU). Higher levels were detected in tissues from patients with Hashimoto's thyroiditis (HT; n = 2; 51.3 +/- 10.3 AU). Cultures of pure thyroid-derived fibroblasts (46 +/- 18 AU thyrocytes (33 +/- 8 AU), and the anaplastic thyroid carcinoma cell lines 8505 C (39 +/- 11 AU), SW 1736 (214 +/- 16 AU) and C643 (3 +/- 1 AU) showed significantly lower TNF-alpha mRNA levels than thyroid-derived lymphocytes (1650 +/- 32 AU). TNF-alpha was detected in the supernatants of unstimulated lymphocytes (22.1 +/- 1.1 pg/ml) and SW 1736 cells (3.5 +/- 0.9 pg/ml), but not in unstimulated fibroblasts and thyrocytes. Using an intracellular labelling technique in flow cytometry, the immunophenotype of stimulated TNF-alpha-positive lymphocytes was determined as predominantly CD3+CD45RO+. Our results suggest that TNF-alpha is present in the thyroid tissue of different thyroid disorders. Thyroid-derived lymphocytes are potential TNF-alpha producers and may thus locally influence thyroid function.

Adult↗
PubMed1996

Differential regulation of granulocyte-macrophage colony-stimulating factor mRNA and protein expression in human thyrocytes and thyroid-derived fibroblasts by interleukin-1 alpha and tumor necrosis factor-alpha.

In this study, we provide the first report on the production of granulocyte-macrophage colony-stimulating factor (GM-CSF) by human thyroid epithelial cells. Primary cultures of highly purified thyrocytes and thyroid-derived fibroblasts (n = 3) and three thyroid anaplastic and one largely papillary carcinoma cell lines were exposed to different potent GM-CSF stimulators, employing interleukin 1 alpha (Il-1 alpha) and tumour necrosis factor-alpha (TNF-alpha). Cytokine mRNA levels were monitored by semi-quantitative reverse transcriptase-PCR including an internal heterologous competitor fragment after 3, 6 and 18 h of culture. Culture supernatants were assayed for GM-CSF using a highly sensitive ELISA (detection limit < or = 0.5 pg/ml) after 24 h. Basal GM-CSF mRNA expression was higher in fibroblasts and SW 1736 cells compared with thyrocytes, C 634, 8505 C and HTh 74 cells. GM-CSF was spontaneously secreted by fibroblasts (means +/- S.E.M.; 43 +/- 15 pg/ml), SW 1736 (59 +/- 4 pg/ml), HTh 74 (34 +/- 4 pg/ml) and C 643 cells (12 +/- 1 pg/ml) but not by thyrocytes and 8505 C cells. Treatment with Il-1 alpha (10 U/ml) resulted in a marked increase of GM-CSF mRNA within 3 h and an increase or induction of protein expression in thyrocyte (2350 +/- 214 pg/ml), fibroblast (5242 +/- 1400 pg/ml), SW 1736 (20016 +/- 280 pg/ml) and C 643 cultures (1285 +/- 79 pg/ml). Stimulation with TNF-alpha (10 U/ml) yielded divergent results. No significant increase of GM-CSF mRNA or protein expression was found in thyrocytes although TNF-alpha receptor expression in these cells is well documented. Stimulation with TNF-alpha resulted in an increased GM-CSF production in fibroblasts (361 +/- 14 pg/ml), HTh 74 (148 +/- 51 pg/ml) and SW 1736 cultures (235 +/- 43 pg/ml). TSH (10 mU/ ml) did not stimulate GM-CSF secretion in thyrocytes and HTh 74 cells, both expressing the TSH receptor. Phorbol 12-myristate 13-acetate (10 ng/ml) enhanced GM-CSF mRNA and protein levels in all cell types investigated. Our data suggest that both thyrocytes and fibroblasts synthesize GM-CSF in response to Il-1 alpha, but only fibroblasts respond to TNF-alpha with a significant increase in GM-CSF. Anaplastic thyroid carcinomas are potential GM-CSF producers.

Carcinoma↗
PubMed1996

[Prophylactic effect of specific egg yolk antibodies in diarrhea caused by Escherichia coli K88 (F4) in weaned piglets].

In this study, the protective effect of specific egg yolk antibodies on diarrhea caused by Escherichia coli K88 (F4) was investigated with 179 weaning piglets in a double-blind field trial. The piglets were divided into three groups. The antibody group received egg powder with specific antibodies to E. coli K88, K99, 987P, and rotavirus, while one control group was fed with egg powder without specific antibodies and a second control group received no egg powder at all. The piglets were fed ad libitum. The egg powder was offered in a 5% feed ration. Compared with the control groups, the piglets of the antibody group showed significant differences (P < 0.05, chi 2-test) in the parameters rate of diarrhea (17.2%) (antibody group) to 60.7% (control egg group) or 56.7% (control group without egg powder), severity of symptoms (5.2-39.3% or 26.7%) and frequency of additional treatments (8.6-55.7% or 51.7%). Because of the additional treatments, no difference could be found in body-weight gain. In control groups, three piglets died, while no pigs died in the antibody group.

Animals↗
PubMed1995

Salbutamol-induced airway hyperreactivity in guinea pigs is not due to a loss of its bronchodilator effect.

Guinea pigs were treated for 10 days with (+/-)-salbutamol (0.2 mg/kg/day, delivered from subcutaneously implanted osmotic minipumps). Airway reactivity to intravenously administered histamine, methacholine and bombesin was substantially increased in salbutamol-treated guinea pigs relative to controls. In the same animals, the potency of intravenously administered salbutamol to reverse bombesin-induced bronchoconstriction remained unchanged thus exactly reflecting effects in man. In conclusion, subchronic administration of salbutamol at low doses to guinea pigs increases airway reactivity. Since the bronchorelaxant effect of salbutamol remained unchanged, desensitisation of beta-adrenoceptors on airway smooth muscle is unlikely to account for this effect.

Adrenergic beta-Agonists↗
PubMed1995

A sparse matrix screen to establish initial conditions for protein renaturation.

Protein renaturation is of particular interest not only for the basic mechanisms of protein folding but also as a practical problem for proteins overexpressed in microorganisms, since recombinant proteins may accumulate as misfolded aggregates in "inclusion bodies" that are inactive after purification. We have established a systematic screening method to identify conditions which promote protein renaturation. A matrix of 50 different buffers, which were originally developed for protein crystallization, were found to facilitate the renaturation for eight of nine different proteins examined. The proteins tested include the adhesive protein bindin, recombinant bindin, and a variety of enzymes, including bacterial alkaline phophatase, horseradish peroxidase, lysozyme, trypsin, beta-galactosidase, rabbit carboxylesterase, and acetylcholinesterase. The total amount of activity recovered varied from 9 to 333% depending on the protein. The conditions that were found to promote renaturation are very different from the optimal conditions for enzyme activity. The finding that most of the proteins tested renatured to a significant extent in one or more of the buffers in the matrix suggests that the sparse matrix screen may be of general utility for establishing initial renaturation conditions for a wide variety of proteins. One initial renaturation conditions have been identified, the conditions may be optimized by systematically altering other parameters of the renaturation process.

Acetylcholinesterase↗
PubMed1995

Structure/function studies on cytoskeletal proteins in Dictyostelium amoebae as a paradigm.

The actin cytoskeleton in motile non-muscle cells is being regulated by a large number of actin-binding proteins. A deeper insight into the complex nature of the dynamic rearrangements of the microfilament system during cell movement requires an experimental system that allows the combined application of biochemical, biophysical, cell biological and molecular methods. Dictyostelium amoebae are well suited especially for a genetic approach because they are amenable to gene disruption, antisense and gene tagging techniques. The actin-binding proteins profilin, hisactophilin and protovillin are being described in this context as typical examples that either bind to G-actin, or anchor the actin cytoskeleton to the plasma membrane, or are structurally similar to vertebrate proteins but distinct in their functions.

Animals↗
PubMed1995

Fundamentals and possibilities of classification of occupational substances as developmental toxicants.

It is now widely accepted that describing and labeling of chemicals as developmental toxicants on a purely qualitative basis does not make sense. Agents possessing the potential to induce reproductive or developmental toxicity present a risk of human harm only under certain conditions. This critical fact cannot be properly communicated with a simple designation as "positive" or "negative". Rather, a number of parameters that deal with dose or concentration, frequency, duration and route of exposure must also be conveyed. Unsubstantiated blacklisting is equally counterproductive for preventive medicine as downplaying of the toxicity of chemicals. Gender-based restrictions on exposure at workplaces of women of child-bearing age are neither socially acceptable nor scientifically justifiable. Therefore, the German Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area published in 1983 a quantitatively based classification concept, which became effective in 1985 and was modified in the following years. The present contribution summarizes what is required for an integrated judgment on the relevance of laboratory and epidemiological data for predicting the potential risk associated with exposure at workplaces to occupational chemicals. Methyl mercury, carbon disulfide, dimethylformamide, ethanol, toluene, N,N-dimethyl acetamide, nitrous oxide, methanol, ethyl benzene, and phosphorus pentoxide will be described as examples of classified substances.

Abnormalities, Drug-Induced↗