Biomarkers of aging - current state of knowledge

Aging is a process of gradual decline in the functional capacity of the human body that leads to a significant increase in the risk of death over time. Although it is a process universal to all animals, its rate is not the same. Biomarkers of aging aim to better describe the aging process at the level of the individual, organ, tissue, or single cell. They are used to estimate the rate of aging and predict the probability of death. They are good indication of the current state of the organism and are more accurate in predicting a person's susceptibility to disease, its progression and the likelihood of complications and death. Simple biomarkers measure only one parameter or a narrow group of related parameters that have a known association with age, in human or in a laboratory model. They can be divided into molecular (based on features of aging), functional (describing decreasing functional capacity during aging) and anthropometric (describing structural changes). Composite biomarkers are the most comprehensive way of measuring biological age. They combine a large amount of data, which they evaluate using algorithms often based on artificial intelligence. The most widely used method for measuring biological age in composite biomarkers is the epigenetic clock. The aim of this article is to review the many existing markers of aging and describe their relationship to aging.

Application of Carbon-Flax Hybrid Composite in High Performance Electric Personal Watercraft

Within the herein presented research, we studied the applicability of flax fabrics for composite parts in personal watercrafts in order to enhance damping of vibrations from the engine and noise reduction (which is relatively high for contemporary carbon constructions). Since the composite parts are intended to be exposed to humid environments requiring high levels of mechanical properties, a carbon-flax composite was selected. Samples of carbon, fiberglass, flax, and hybrid carbon-flax twill and biax fabrics were subjected to tensile and three-point bending tests. The mechanical properties were also tested after exposure of the samples to a humid environment. Damping was assessed by vibration and noise measurements directly on the complete float for samples as well as real parts. The hybrid carbon-flax material exhibited lower values of tensile strength than the carbon material (760 MPa compared to 463 MPa), but, at the same time, significantly higher than the other tested materials, or flax itself (115 MPa for a twill fabric). A similar trend in the results was observed for the three-point bending tests. Vibration tests and noise measurements showed reductions in vibration amplitude and frequency when using the carbon-flax hybrid material; the frequency response function for the watercraft part assembled from the hybrid material was 50% lower than for that made of carbon. Testing of samples located in a humid environment showed the necessity of surface treatment to prevent moisture absorption (mechanical properties were reduced at minimum by 28%). The tests confirmed that the hybrid material is satisfactory in terms of strength and its contribution to noise and vibration damping.

Physiology of ageing

Aging is a process of gradually reducing abilities and functional capacities of the organism. It is a universal process with a considerable degree of variability that is characteristic of all higher animals. Among the theories of ageing, the theory of damage accumulation, which integrates the mechanisms of ageing known to date, is currently widely accepted. This theory is based on pathophysiological processes, injurious changes can occur in the human body. These changes can be understood as damage. Due to the continuous accumulation of damage, the whole system is subsequently deteriorated. The aim of the present work is to characterize the basic pathophysiological mechanisms of aging (damage) in the light of current scientific knowledge and to show them in their hierarchical context.

C-reactive protein, chemerin, fetuin-A and osteopontin as predictors of cardiovascular risks in persons with psoriasis vulgaris

The study aimed to contribute to understanding the role of CRP, chemerin, fetuin-A and osteopontin and to assess their suitability as biomarkers of early stages of cardiovascular diseases in psoriasis vulgaris. Serum levels measured in 28 patients and 22 controls. Patients: increased levels of CRP (p<0.001), chemerin (p<0.05), osteopontin (p<0.05) and decreased levels of fetuin-A (p<0.05), significant relationships between CRP and fetuin-A (rho=0.530, p<0.01), CRP and chemerin (rho=0.543, p<0.01), CRP and age (rho=0.590, p<0.001), osteopontin and fetuin-A (r=-0.415, p<0.05), chemerin and PASI score (rho=-0.424, p<0.05). We confirmed specific roles of the biomarkers in psoriasis. CRP, fetuin-A and osteopontin could be considered appropriate markers for the detection of early stages of cardiovascular diseases.

Goeckerman Regimen Reduces Alarmin Levels and PASI Score in Paediatric Patients with Psoriasis

BACKGROUND

Psoriasis is a chronic systemic inflammatory disease with (extra-)cutaneous manifestations. Inflammation is associated with cellular stress and tissue damage which lead to the release of alarmins (signals of danger). Goeckerman regimen (GR) is a highly efficacious treatment consisting of the application of pharmaceutical crude tar and UVB light exposure. The reduction of inflammatory processes in the skin is accompanied by changes in the levels of inflammatory markers - alarmins (HMBG-1, S100A7, S1000A8, S100A9, S100A12, IL-17, IL-22, and IL-33).

METHODS

The alarmin levels in sera of 19 paediatric patients with psoriasis were determined before and after GR using commercial ELISA kits. The Psoriasis area severity index (PASI) was used to determine the disease severity.

RESULTS

GR reduced both PASI and the levels of all measured alarmins. The levels of S100A7, S100A9, IL-22, IL-33, and HMGB-1 were significantly decreased. Positive correlations between IL-22 and PASI, between S100A9 and IL-17, S100A9 and IL-22, and a negative correlation between S100A8 and IL-33 were found.

CONCLUSIONS

Goeckerman regimen is a very effective, safe and low-cost therapy. We confirmed, it modulates the immune system reactivity, ameliorates the severity of the disease and reduces the levels of alarmins reflecting the presence and intensity of inflammation.

Quality of life of patients with psoriasis

OBJECTIVE

The two main aims of our study were to assess the quality of life (QOL) of patients with moderate or severe psoriasis treated by Goeckerman therapy and to compare QOL of our patients on the date of admission and 1 month after their discharge.

METHODS

We performed a prospective study on 51 patients treated for chronic plaque psoriasis by Goeckerman regimen (GR). The psoriasis area involvement and severity was measured using the Psoriasis Area and Severity Index (PASI). Patients' health-related QOL was evaluated using Psoriasis Disability Index (PDI).

RESULTS

In our study we demonstrated that the QOL of this sample of 51 patients with severe forms of psoriasis was relatively good; an average PDI value on the day of admission was 9.02, which represents a small effect on patient's QOL. We did not find any significant differences in QOL between younger and older respondents or between men and women. Despite good treatment efficiency, we did not find improvement in QOL 1 month after discharge.

CONCLUSIONS

The QOL of our patients was relatively good. This could be explained by the fact that our patients have been suffering from psoriasis for many years and have probably adapted to their disease. QOL of our patients was not directly dependent on the extent and intensity of skin changes. Further studies on the connection between psoriasis therapy and patients' QOL are still highly needed.

Variation of selected genotoxic and epigenetic markers due to therapeutic exposure to PAHs and ultraviolet radiation

BACKGROUND

Goeckerman therapy (GT) of psoriasis involves dermal application of crude coal tar containing polycyclic aromatic hydrocarbons (PAHs) and exposure to ultraviolet radiation (UVR). Little is known about GT influence on DNA epigenetics.

OBJECTIVE

The study aim was to discover epigenetic mechanisms altered by the exposure related to the GT of psoriasis.

METHODS

Observed group of patients with plaque psoriasis (n = 23) was treated by GT with 3 % CCT. Before and after GT, we analyzed the levels of benzo[a]pyrene-7,8-diol-9,10-epoxide-DNA adducts (BPDE-DNA), p53 protein in serum, 5-methylcytosine (5-mC, global DNA methylation), and methylation in selected CpG sites of p53 gene.

RESULTS

We found a significant increase in the levels of BPDE-DNA (p < 0.01) and serum levels of p53 protein (p < 0.01) after GT, and an insignificant decrease in the percentage of 5-mC in peripheral blood DNA. Methylation of p53 CpG sites was affected neither by psoriasis nor by GT. The study confirmed good effectiveness of GT (significantly reduced psoriasis area and severity index; p < 0.001).

CONCLUSION

Our findings indicate that there is a significantly increased genotoxic hazard related to the exposure of PAHs and UV radiation after GT of psoriasis. However, global DNA methylation and p53 gene methylation evade the effect of GT, as they remained unchanged (Tab. 4, Fig. 3, Ref. 50).

Immunosuppressive Effect of Polycyclic Aromatic Hydrocarbons by Induction of Apoptosis of pre-B Lymphocytes of Bone Marrow

Polycyclic aromatic hydrocarbons (PAH) are ubiquitous environmental pollutants, distinguished by genotoxic, hepatotoxic, nephrotoxic and immunotoxic effects. Especially secondary toxicity after bioactivation by microsomal monooxygenases (dependent on cytochromes P450) is characteristic of them. The immunotoxic effect is the result of very global impact on immunological reactivity of an organism and immunosuppression by induction of apoptosis of pre-B lymphocytes represents one of its particular forms. It has been proved that the effect of PAH is caused mostly by the following mechanisms: enzymatic induction by the way of activation of AhR (Aromatic hydrocarbon Receptor); alteration of cellular DNA; development of oxidative stress; increase in the concentration of intercellular calcium and decline of activity of NF-κB (Nuclear Factor – kappa B). Most sensitive to these changes are particularly B-lymphocytic precursors and pre-B lymphocytes. Intensity of entire manifestations is also considerably dependent on the presence and intensity of mechanisms of active or passive resistance of cells.

Health Risk of Occupational Exposure in Welding Processes II. Immunological Effects

Many of epidemiological studies have certified the relationship between welding and various forms of health damages. In our study we performed an immunological research within a group of twenty men, working in the risky environment of manufacturing of stainless steel constructions (11 welders and 9 grinders, average age was 31 years, 55 % of smokers, average time period in welding occupational exposure was 8 years). The exposed group of men was compared with a group of healthy blood donors, marked as the control group (people with various types of employment, living in same locality as a people from exposed group). People within the control group were not occupationally exposed to harmful chemical compounds (from 30 to 100 men were chosen for the individual immune parameters, average age of the whole group was 38 years, 40 % of smokers). When compared with the control group, the exposed group of welders and grinders showed higher level of C3 complement (p<0.001), orosomucoid (p<0.05), beta-2–microglobulin (p<0.001), neopterin (p<0.001) and all fagocytic cells (p<0.001). On the contrary, in the group of exposed people decreased values of IgA (p<0.001), IgG (p<0.001), IgM (p<0.001), transferin (p<0.001), alpha-1–antitrypsin (p<0.001), alpha-2–macroglobulin (p<0.001), haptoglobulin (p<0.001) and ceruloplasmin (p<0.05) were found. Some of these changes were characteristic for the exposed group. They could be considered as precursors of biological markers of effect for given type of exposure.

Health Risk of Occupational Exposure in Welding Processes I. Genotoxic Risk

The welding processes belong among the important sources of occupational pollutions. The welding fumes are ranked, according to the classification of IARC (International Agency for Research on Cancer), into the group of 2B. In our study we have performed the investigation of twenty men (exposed group) working in the stainless steel welding industrial processes (11 welders and 9 grinders, average age was 31 years, 55 % of smokers, average time period of welding occupational exposure was 8 years). The concentrations of chromium (0.557–16.343 mg/m3) and nickel (0.340–10.129 mg/m3) in occupational atmosphere highly exceeded established values of maximum permitted concentrations (0.1 and 1.0 mg/m3, respectively). The concentrations of manganese did not exceed its permitted values. Total concentrations of 12 polycyclic aromatic hydrocarbons (PAH) in occupational atmosphere varied from 300.9 to 961.2 ng/m3. For purposes of biological monitoring, the levels of chromosomal aberrations were determined in the exposed and control group. Healthy blood donors servedas a control group. People from that group were not occupationally exposed to harmful chemical compounds (20 men, average age was 36 years, 40 % of smokers). Increased level of chromosomal aberrations of exposed group brought the evidence about higher genotoxic risk of investigated welding processes.

Assessment of work-related stress by using salivary cortisol level examination among early morning shift workers

OBJECTIVE

Early morning shifts have a negative effect on the hypothalamic-pituitary-adrenal axis. The aim of this study was to comprehensively assess the extent of occupational stress in early shift workers of the car industry by using salivary cortisol as an objective marker during a workday and on a day off.

METHODS

For this cross-sectional epidemiological type of study, a survey included 55 suitable volunteers from the car industry. Five saliva samples were collected according to the following schedule: during one work day in the morning, during the morning shift from 6 a.m. - 2 p.m., then after the shift was completed, 3 hours after work and in the evening before going to sleep. Control samples were taken from the same participants on a day off. Radioimmunoanalysis was used as the main analytical method, and the effect of factors and between-factor interactions on the levels of salivary cortisol during the workday were assessed using an ANOVA model.

RESULTS

The cortisol diurnal rhythm was as expected, with the highest values in the morning and declining to the lowest values in the evening hours. Concentrations of salivary cortisol showed higher values during the workday, especially higher concentrations of evening cortisol and attenuated cortisol slope. Based on the results, irregular shift work has a greater increase in cortisol excretion after waking in the morning and a slower progressive recovery of the organism during the workday. In addition, cortisol levels were significantly higher in older women than in older men but did not differ in younger subjects.

CONCLUSIONS

Salivary cortisol levels are a suitable objective marker of stress and can be used as a good predictor of occupational stress by public health services for the purposes of primary prevention.

Serum Levels of Aryl Hydrocarbon Receptor, Cytochromes P450 1A1 and 1B1 in Patients with Exacerbated Psoriasis Vulgaris

The aryl hydrocarbon receptor (AhR) is highly expressed in psoriasis skin lesions. The aim of this study was to investigate serum concentrations of AhR, cytochromes P450 (CYP) 1A1 and 1B1 in patients with exacerbated psoriasis vulgaris treated with combined therapy of ultraviolet radiation (UVR) and crude coal tar. The analyses were performed by using enzyme-linked immunosorbent assays. Before the treatment, the patients had significantly higher serum levels of AhR and CYP1A1 than healthy controls. AhR median noticeably decreased after the therapy; nevertheless, it remained significantly higher compared to the controls. CYP1A1 levels measured before and after the therapy did not differ significantly. Serum CYP1A1 positively correlated with AhR values before and after the treatment. The serum values of CYP1B1 were very low and we did not see any differences between the study group and the control group. The study demonstrated that serum levels of AhR and CYP1A1 could indicate their immunopathological and metabolic roles in exacerbated psoriasis.

Roles of miR-31 and endothelin-1 in psoriasis vulgaris: pathophysiological functions and potential biomarkers

Psoriatic lesions are characterized by hyperproliferation, aberrant differentiation of keratinocytes resistant to apoptosis and inflammation. miR-31 plays pro-proliferative, pro-differentiative and pro-inflammatory roles and modulates apoptosis in psoriatic keratinocytes. Endothelin-1 (ET-1) is produced by psoriatic keratinocytes and suppresses apoptosis. Inflammation increases the production of ET-1, which in turn leads to the chronic stimulation of keratinocyte proliferation. The aim of this study was to identify the putative link between two potential biomarkers (miR-31 and ET-1) in patients with psoriasis. The study design included experimental group (29 patients with psoriasis), and the control group (22 blood donors). The PASI score evaluated the state of the disease (median: 18.6; interquartile range 14.5-20.9). Both, the serum level of ET-1 and the whole blood level of miR-31 were significantly increased (p<0.001 and p<0.05, respectively) in patients compared to the controls. However, a significant negative relationship between ET-1 and miR-31 was observed (Spearman's rho=-037, p=0.05). It is possible that a negative feedback loop will be present between miR-31 and ET-1. Our results indicate that miR-31 and ET-1, potential biomarkers of the disease, play significant roles in the pathophysiology of psoriasis.

Smoking Related Systemic and Oral Diseases

This article reviewed smoking related systemic diseases and oral diseases. Smoking is related to lung cancer, cardiovascular diseases and many other systemic diseases. Cigarette smoke affects the oral cavity first, so it is evident that smoking has many negative influences on oral cavity, for example, staining of teeth and dental restorations, wound healing, reduction of the ability to smell and taste, and development of oral diseases such as oral cancer, periodontitis, smoker’s palate, smoker’s melanosis, hairy tongue, leukoplakia, oral candidiasis and implant survival rate. The article also discusses the relationship between smoking and dental caries in detail.

SAMPA: A free software tool for skin and membrane permeation data analysis

Skin and membrane permeation experiments comprise an important step in the development of a transdermal or topical formulation or toxicological risk assessment. The standard method for analyzing these data relies on the linear part of a permeation profile. However, it is difficult to objectively determine when the profile becomes linear, or the experiment duration may be insufficient to reach a maximum or steady state. Here, we present a software tool for Skin And Membrane Permeation data Analysis, SAMPA, that is easy to use and overcomes several of these difficulties. The SAMPA method and software have been validated on in vitro and in vivo permeation data on human, pig and rat skin and model stratum corneum lipid membranes using compounds that range from highly lipophilic polycyclic aromatic hydrocarbons to highly hydrophilic antiviral drug, with and without two permeation enhancers. The SAMPA performance was compared with the standard method using a linear part of the permeation profile and a complex mathematical model. SAMPA is a user-friendly, open-source software tool for analyzing the data obtained from skin and membrane permeation experiments. It runs on a Microsoft Windows platform and is freely available as a Supporting file to this article.

Serum Level of Antibodies (IgG, IgM) Against Benzo[a]pyrene-7,8-diol-9,10-epoxide-DNA Adducts in Children Dermatologically Exposed to Coal Tar

Crude coal tar (CCT) contains polycyclic aromatic hydrocarbons (PAHs). Benzo[a]pyrene (BaP) is metabolized into a highly reactive metabolite benzo[a]pyrene-7,8-diol-9,10-epoxide (BPDE) that is able to bind to DNA and creates BPDE-DNA adducts. Adducted DNA becomes immunogenic and induces immune response by production of antibodies against BPDE-DNA adducts (Ab-BPDE-DNA). Circulating Ab-BPDE-DNA was proposed as potential biomarker of genotoxic exposure to BaP (PAHs). Goeckerman therapy (GT) of psoriasis uses dermal application of CCT ointment (PAHs). In presented study (children with psoriasis treated by GT; n = 19) the therapy significantly increased the level of Ab-BPDE-DNA (EI = 0.29/0.19-0.34 vs. 0.31/0.25-0.40; median/lower-upper quartile; p < 0.01). The results support the idea of Ab-BPDE-DNA level as a possible tentative indicator of exposure, effects and susceptibility of the organism to the exposure of BaP (PAHs).

CC and CXC Chemokines Patterns in Psoriasis Determined by Protein Array Method Were Influenced by Goeckerman’s Therapy

Goeckerman’s therapy (GT) of psoriasis is based on daily application of pharmacy grade coal tar on affected skin with subsequent exposure to UV light. The aim of this study was to evaluate the influence of Goeckerman’s therapy of psoriasis on the levels of proangiogenic chemokines ENA-78 (CXCL5, Epithelial Cell Derived Neutrophil Attractant- 78), GRO alpha (CXCL1, Growth-Related Oncogene), IL-8 (CXCL8, Interleukin-8), MCP-1 (CCL2, Monocyte Chemotactic (Chemoattractant) Protein 1) and RANTES (CCL5, Regulated on Activation of Normal T Cell Expressed and Secreted) in peripheral blood of 22 children’s patients with psoriasis. 22 otherwise healthy children serve as a control group. The serum levels of chemokines were determined by commercial membrane protein array technique (RayBiotech, USA). Efficacy of Goeckerman’s therapy was delineated by PASI score. Disease activity was significantly diminished by Goeckerman’s therapy (p<0.001). Serum levels of GRO alpha and MCP-1 in patients before GT were significantly higher than those measured in healthy blood donors (GRO alpha: p=0.0128 and MCP-1: p=0.0003). Serum levels of GRO alpha, MCP-1 and RANTES were significantly diminished by GT (GRO alpha: p=0.002, MCP-1: p=0.048 and RANTES: p=0.0131). Compared to the healthy controls, serum level of MCP-1 remained significantly increased in psoriasis patients after GT (p<0.0001). In conclusion, we found that the GT of psoriasis influenced the serum levels of proinflammatory and proangiogenic chemokines, especially GRO alpha, MCP-1 and RANTES. It could be the cause for decreased proangiogenic activity which is described after GT of psoriasis.

Droplet Digital PCR Analysis of GSTM1 Deletion Polymorphism in Psoriatic Subjects Treated with Goeckerman Therapy

Goeckerman therapy (GT) represents an effective treatment of psoriasis including a combination of pharmaceutical grade crude coal tar (CCT) and ultraviolet irradiation (UV-R). Coal tar contains a mixture of polycyclic aromatic hydrocarbons. The best known carcinogenic polyaromate - benzo[a]pyrene is metabolized into a highly reactive benzo[a]pyrene-7,8-diol-9,10-epoxide (BPDE). Glutathione S-transferase M1 (GSTM1) catalyses the conjugation of drugs, toxins and products of oxidative stress with glutathione. The aim of the study is to found possible associations between GSTM1 genotypes and the level of BPDE-DNA adducts in 46 psoriatic patients treated with GT. For genotyping, droplet digital PCR was applied. The GSTM1 copy number was normalized to β-globin reference gene. In five GSTM1*1/*1 subjects, the GSTM1 to β-globin ratio moved from 0.99 to 1.03 with a median of 1.01. GSTM1*0/*1 heterozygotes (n = 20) contained only one GSTM1 function allele which conditioned the ratio 0.47-0.53 (median 0.50). GSTM1*0/*0 individuals (n = 21) showed no amplification of the null variants because of the large deletion in GSTM1. BPDE-DNA concentrations ranged from 1.8 to 66.3 ng/µg with a median of 12.3 ng/µg. GSTM1*0/*0 and GSTM1*0/*1 genotypes showed non-significantly higher concentrations of BPDE-DNA adducts than the GSTM1*1/*1 one (12.3 and 12.4 vs 7.8 ng/µg). The non-significant relationship between BPDE-DNA adducts and GSTM1 genotypes in psoriatic patients could be associated with relatively low doses of CCT and short-term UV-R exposures used in GT.

Regulatory T cells (Treg) and Their Roles in Immune System with Respect to Immunopathological Disorders

Regulatory T cells (Tregs) are a specialized subpopulation of T cells that act to suppress immune response, thereby maintaining homeostasis and self-tolerance. It has been shown that Tregs are able to inhibit T cell proliferation and cytokine production and play a critical role in preventing autoimmunity. Different subsets with various functions of Treg cells exist. Tregs can be usually identified by flow cytometry. The most specific marker for these cells is FoxP3, which is localized intracellulary. Selected surface markers such as CD25high (high molecular density) and CD127low (low molecular density) could serve as surrogate markers to detect Tregs in a routine clinical practice. Dysregulation in Treg cell frequency or functions may lead to the development of autoimmune disease. Therapeutical Treg modulation is considered to be a promising therapeutical approach to treat some selected disorders, such as allergies, and to prevent allograft rejection.

The Number of Immunoregulatory T Cells is Increased in Patients with Psoriasis after Goeckerman Therapy

Regulatory T cells (Treg) are a specialized subpopulation of T cells that act to suppress inadequate immune response. Psoriasis is recognized as a T-cell driven immune-mediated systemic inflammatory disease with skin manifestation. Effective therapeutical approach to treat psoriasis is Goeckerman therapy (GT). The aim of this study was to compare the number of Treg in the peripheral blood of 27 psoriatic patients and 19 controls and to evaluate the influence of GT on Treg population in peripheral blood of patients with psoriasis. There was no significant difference in the relative number of Treg cells in the peripheral blood of healthy blood donors and patients with psoriasis before initiation of GT (P = 0.2668). In contrary, the relative number of Treg cells in peripheral blood of patients with psoriasis after GT was significantly higher than those found in healthy blood donors (P = 0.0019). Moreover, the relative number of Treg is significantly increased in psoriatic patients after Goeckerman therapy compared to the pre-treatment level (P = 0.0042). In conclusion, this significant increase in Treg count after GT is probably associated with amelioration of inflammation by GT, as disease activity expressed as PASI decreased in our patients by GT (P = 0.0001).

Elevated levels of circulating biomarkers of cell death (nucleosomes) in the patients with plaque psoriasis treated with the Goeckerman regimen

BACKGROUND

Nucleosomes are complexes that are formed during apoptosis. Psoriasis is a chronic skin disease characterized by keratinocyte hyperproliferation and anti-apoptotic features. Presented study was focused to expression of circulating biomarkers of cell death (circulating nucleosomes, CN) during Goeckerman therapy of psoriasis (UV, PAHs).

METHODS

In a group of patients with psoriasis (19), treated with Goeckerman regimen (GR), we evaluated their level of CN, level of chromosomal aberration in peripheral lymphocytes (CA), level of urinary 1-hydroxypyrene (1-OHP) and their value of Psoriasis Area and Severity Index (PASI).

RESULTS

Following the treatment, the serum level of CN and urinary level of 1-OHP (p<0.05) were significantly increased (p<0.01). We found significant correlation between CN and urinary level of 1-OHP after GR (r=0.57; p<0.05). Immediately after the treatment we found significantly increased total numbers of abnormal chromosomes (ABB; p<0.01) and structurally abnormal chromosomes (SAB; p<0.05).

CONCLUSIONS

We found slightly (but statistically significant) elevated level of circulating biomarkers of cell death (nucleosomes) in patients with plaque psoriasis treated with GR (PAHs, UV radiation). We suppose that elevated level of CN is a result of combination of the positive effects of GR and its weak genotoxic effect (mainly PAHs). Conclusions are supported by significant correlation between CN and urinary level of 1-OHP after GR and significantly elevated level of CA after GR (Tab. 2, Fig. 1, Ref. 28).

Angiogenic activity in patients with psoriasis is significantly decreased by Goeckerman’s therapy

Goeckerman's therapy (GT) of psoriasis is based on daily application of pharmacy grade coal tar on affected skin with subsequent exposure to UV light. Goeckerman's therapy is still the first line therapy of psoriasis in the Czech Republic because of its low cost and long-term efficacy. Disturbances in angiogenic activity are characteristic for the immunopathogenesis of psoriasis. An abnormal spectrum of cytokines, growth factors and proangiogenic mediators is produced by keratinocytes and inflammatory cells in patients suffering from the disease. The aim of this study was to evaluate the influence of GT of psoriasis on angiogenic activities by comparing serum levels of vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) in 44 patients with psoriasis in peripheral blood samples collected before and after therapy. Forty otherwise healthy blood donors serve as a control group. The efficacy of GT was delineated by psoriasis area and severity index (PASI). The disease activity was significantly diminished by GT (P < 0.001). The serum levels of both VEGF and bFGF were statistically significantly correlated to PASI value in patients before the treatment by GT. The serum levels of VEGF (329.4 +/- 125.5 microg/ml) and bFGF (10.2 +/- 5.04 pg/ml) in patients before GT were significantly higher than those measured in healthy blood donors (VEGF 236.4 +/- 55.9 pg/ml, bFGF 7.3 +/- 3.7 pg/ ml). The serum levels of both VEGF and bFGF were significantly diminished by GT. The level of VEGF dropped from 329.4 +/- 125.5 pg/ml before GT to 278.5 +/- 109.9 pg/ml after GT (P = 0.0042) and the level of bFGF fell from 10.2 +/- 5.04 to 7.78 +/- 4.5 pg/ml (P = 0.019). Comparing to healthy controls, the serum level of bFGF in psoriasis patients was normalised (P = 0.5723) after GT. In contrast, the serum level of VEGF remained significantly increased in psoriasis patients after GT in comparison with healthy blood donors (P = 0.0319). In conclusion, we found that the angiogenic potential which is abnormally increased in patients with psoriasis is significantly alleviated by GT.

Selected immunological changes in patients with Goeckerman’s therapy TNF-alpha, sE-selectin, sP-selectin, sICAM-1 and IL-8

Psoriasis is one of the most frequent inflammatory skin diseases in which abnormal individual immune reactivity plays an important role. The aim of the present study was to describe selected immunological changes, concerning pro-inflammatory cytokines (TNF-alpha, IL-8) and adhesion molecules (sE-selectin, sP-selectin, sICAM-1), in 56 patients cured by Goeckerman's therapy (GT). GT includes dermal application of crude coal tar (containing polycyclic aromatic hydrocarbons) and exposure to UV radiation. When compared with the control group (healthy blood donors), the patients before GT had significantly increased serum levels of sE-selectin (p<0.001), sP-selectin (p<0.001), sICAM-1 (p<0.001) and IL-8 (p<0.001). Significantly decreased serum levels of sE-selectin (p<0.05) and significantly increased serum levels of IL-8 (p<0.05) were found after GT therapy. Serum levels of sICAM significantly correlated with the disease activity and with serum levels of sE-selectin. The level of PASI score (Psoriasis Area and Severity Index) significantly decreased after GT (p<0.001) and confirms the high efficiency GT. These findings confirmed that pro-inflammatory chemokine (IL-8) and adhesion molecules (sE-selectin, sP-selectin, sICAM-1) play an important role in the development and regulation of inflammation in psoriasis. Determination of sE-selectin and sICAM seems to be a promising marker of psoriasis's activity. Chemokine pathway (IL-8) and TNF-alpha activity seem to be modulated by Goeckerman's therapy (polycyclic aromatic hydrocarbons).

Cytogenetic and immunological changes after dermal exposure to polycyclic aromatic hydrocarbons and UV radiation

Goeckerman's therapy (GT), which combines exposure to coal tar (polycyclic aromatic hydrocarbons - PAHs) and UV radiation (UV) is often used as the first option for treatment of psoriasis. However, PAHs and UV represent mutagenic, carcinogenic and immunotoxic agents. Therefore GT can represent a health risk for the patients. The group under observation consisted of thirty patients undergoing GT. Before and after the treatment, blood samples were collected and chromosomal aberrations and selected immunological markers were determined. The relationships between chromosomal aberrations and immunological markers and the extent (duration) of exposure to GT were evaluated. The Psoriasis Area and Severity Index (PASI) score confirmed the high efficacy of GT. However, significantly elevated levels of chromosomal aberrations of peripheral lymphocytes were also found after the therapy (p<0.001). The levels of chromosomal abnormalities correlated to the extent and the total duration of exposure to PAHs (r = 0.682, p<0.01 and r = 0.605, p<0.05). After the therapy, significantly decreased levels of IgE, IgM isotypes of immunoglobulin, alpha(2)-macroglobulin and transferrin together with beta(2)-microglobulin were found. From the immunological markers listed above only the decreased level of alpha(2)-macroglobulin correlated to the extent of exposure to PAHs (r = -0.568, p<0.05). No correlation was found between chromosomal aberrations, significantly changed immunological markers and the duration of UV exposure. Our study revealed that GT has a significant impact on both genetic and immunological parameters of psoriatic patients. The results indicate that GT could increase genotoxic risk and modulates immunity of treated patients.

Possible genotoxic risk of combined exposure to pharmaceutical coal tar and UV-B radiation

Goeckerman's therapy of psoriasis combines exposure to pharmaceutical coal tar and UV-B radiation. In the pilot study (15 patients had been diagnosed with psoriasis, the average time period in hospital therapy was 24 days, the average age of the patients was 29 years, 47% of them were smokers) a level of genotoxic risk from therapy was evaluated by using chromosomal aberration of peripheral lymphocytes. The study suggested the presence of an increased genotoxic risk from the therapy. The PASI scores (Psoriasis Area and Severity Index) were monitored.

[New findings in monitoring health status of welders and grinders of stainless steel]

During the occupational preventive care check up we investigated a group of 20 stainless steel welders and grinders in the factory producing technology for chemical industry. Results have been compared with 21 healthy persons--blood donors. In the group exposed there have not been discovered any marked deviations in either their health status, or in the CBC and biochemical screening results, though there had been found substantially increased chromium and nickel concentrations, mainly in grinders. Also the levels of polycyclic aromatic hydrocarbons were in some cases even higher than on the busy city crossing. The chromosome aberrations investigations proved to be very sensitive and confirmed that employees of the followed up factory are exposed to an increased genotoxic risk.

Environmental exposure of small children to polycyclic aromatic hydrocarbons

OBJECTIVES

The aim of the study was to assess the intake (by various routes of exposure) of polycyclic aromatic hydrocarbons (PAH) by children living in a Czech city, and its effect on excretion of 1-hydroxypyrene (1-OHP) in summer and winter periods.

METHODS

Four groups of children (3-6 years old) were chosen: (1) two groups from a kindergarten situated in the city center with a higher traffic density ("polluted" area); (2) two groups from a kindergarten situated in a green zone of the same city ("non-polluted" area). Food consumption was recorded in all children and PAH intake from foodstuffs was estimated. Ambient air samples were collected from the playground and inside the kindergartens. Soil samples were collected too. Morning and evening urine samples were collected during sampling days.

RESULTS

In both seasons, the mean outdoor total PAH concentration (sum of 12 individual PAH) in the -polluted" area was approximately three-times higher than that in the "non-polluted" area. Indoor concentration in the "polluted" area was more than six-times higher than that in the "non-polluted" area in summer, and almost three-times higher in winter. The same trend was observed for pyrene and for the sum of carcinogenic PAH. The contribution to the total pyrene absorbed dose from food consumption was much more important than that from inhalation and from ingestion of soil dust. Significantly higher urinary concentrations of 1-OHP (evening samples) were found in children from the "polluted" kindergarten in both seasons. The number of significant relationships between 1-OHP and pyrene absorbed dose was weak.

CONCLUSIONS

Food seems to be the main source of total pyrene and total PAH intake in small children, even under relatively higher air PAH exposure in the city. Estimated pyrene ingestion from soil had a negligible contribution to the total pyrene absorbed dose. Urinary 1-OHP seems to be an uncertain (non-sensitive) marker of the environmental inhalation exposure to pyrene (PAH) if the pollution of air by pyrene (PAH) is not excessive and the pyrene (PAH) dose by this route is much less than by ingestion. Usefulness of the urinary 1-OHP as an indicator of overall environmental exposure to PAH needs further investigation.

[Effect of polycyclic aromatic hydrocarbons on the immune system]

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous compounds in our environment. They are formed during incomplete burning of coal, oil, gas, wood, garbage or other organic substances such as tobacco and charbroiled meat. PAHs enter the environment mostly as releases to air from volcanoes, forest fires, residential wood and coal burning and exhaust from automobiles and trucks. There are more than 100 different PAHs. Some of them have danger toxic properties including mutagenic and carcinogenic potential. Since 1993 PAHs are classified as the compounds which can cause immunosuppression. They reduce the body resistance against infection and cancer diseases. Immunosuppressive, carcinogenic and hypersensitivity effects of some PAHs representatives were described well in experimental studies. On the other hand, only sporadic information about immunological changes after long-term occupational exposure to PAHs were found from existing human epidemiological database. In addition, these studies usually did not cover the complex immunological profile represented by cellular and humoral activity.

[Phenotyping of cytochrome P-450 1A2 and N-acetyltransferase (NAT2) using the in vivo caffeine test as a tool for determining individual susceptibility to selected xenobiotics]

An in vivo phenotyping method of CYP1A2 (cytochrome P-450 1A2) and NAT2 (N-acetyltransferase, isoform 2) based on caffeine test (Butler et al. Pharmacogenetics 1992;2:116-127) with modifications has been established. Molar concentrations of caffeine and its metabolites in urine were determined by HPLC with gradient elution and spectral detection (200-350 nm). The results obtained with this method were sufficiently accurate and precise and allowed to calculate the respective parameters which were subsequently used to evaluate the CYP1A2 and NAT2 activities.

[Polycyclic aromatic hydrocarbons. II. Toxic effects]

Polycyclic aromatic hydrocarbons (PAH) represent dangerous environmental pollutants. Many of them have toxic and carcinogenic potential. Presented work summarizes most of available data on the absorption, metabolism and elimination of PAH. The second part of article contains descriptions and evaluations of toxicological studies and epidemiological investigations and provides conclusions, where possible, on the relevance of toxicity and toxicokinetic data to public health. In the third part of article, the populations with higher susceptibility to exposure to PAH are described and the influences of chemical interaction of PAH to biological effects are mentioned.

[Polycyclic aromatic hydrocarbons. Biological indicators of exposure and possibilities of prevention]

Polycyclic aromatic hydrocarbons (PAH) represent an extensive group of ubiquitous environmental pollutants disposing of a considerable toxic and carcinogenic potential. According to the IARC data (International Agency for Research on Cancer), PAH represent the largest group of chemical carcinogens produced during combustion, pyrolysis and pyrosynthesis of organic matter. PAH can be identified in atmosphere, water, soil, food and other materials which are in daily contact which the general population. Presented work summarizes most of available data on the biological markers used to identify or quantify the exposure to PAH and on the biological markers used to characterize the effects caused by PAH. The digest of possibilities of reduction toxic effects of PAH concludes the work.

[Polycyclic aromatic hydrocarbons. I. Environmental contamination and environmental exposure]

Polycyclic aromatic hydrocarbons (PAHs) represent danger ubiquitous environmental pollutants. A lot of them have toxic and carcinogenic potential. Presented work summarises most of available data describing properties, origin and occupational and non-occupational sources of PAHs. Contamination of environment is described separately for air, water, soil, sediments and food. Possibilities of occupational and non-occupational exposure of persons are discussed and populations with potentially high exposures to PAHs are defined. The work is concluded by digest of regulations and guidelines regarding environmental contamination of PAHs.

[Biological monitoring of occupational exposure in welders of stainless steel. Immunologic methods]

Biological monitoring of occupational exposure to toxic compounds enables an early detection of adverse health effects. Apart from the standard biological monitoring methods of occupational exposure represented by metabolites and enzymes activities analysis also immunological detection methods seem to be promising. The changes of immunological system are demonstrable extraordinary sensitive markers of load of organism. The process of welding belongs between important sources of pollution of working environment with heavy metals and other harmful compounds including polycyclic aromatic hydrocarbons. According to IARC classification the welding fumes are included into group 2B and are supposed as possible human carcinogens. Numbers of different epidemiological studies have proved relationship between welding and serious health disorders namely malignancies. We recorded a number of changes in immunological parameters when compared with those in control group in our study. The results of analysis were statistically evaluated. The statistically significant reduction of number of phagocytosis capable cells was found in the group of welders when compared with the control group. The levels of neopterin, beta-2-microglobulin and IL-1 beta have indirectly monitored cell component of immunological response. In the case of these markers a statistically significant increases were found in the group of welders. We found statistically significant IgM decrease and statistically significant IgA increase in humoral responses with the same group when compared with control group.

[Health status of persons occupationally exposed to chromium, nickel, manganese and polycyclic aromatic hydrocarbons]

Occupational environment monitoring and biological-medical monitoring of persons professionally exposed to welding fumes have been performed. Chromium, manganese and polycyclic aromatic hydrocarbons in welding fumes represents an important health risk. Pollutant concentrations found in metal welding fumes represented only fractions of those acceptable ones. Polycyclic aromatic hydrocarbons have been reached the concentration found in a busy road crossing in Hradec Králové (compared with these as in Czech Republic no maximum acceptable levels for PAHs having been declared). Family, personal and occupational history have been taken. Health state including total haematological count, biochemical and cytogenetical changes of 19 stainless steel welders were checked-up. The level of mercapturates in urine were examined as well. The data were statistically compared with those of non exposed (control group). No changes witnessing the above mentioned risk factors influence on the haematological, biochemical and cytogenetical findings were ever proved. In conclusion, our results did not confirm an increased professional risk in this group of welders.

Assessment of multipathway exposure of small children to PAH

The aim of study was to assess the uptake of polycyclic aromatic hydrocarbons (PAH) by children living in a city and its effect on 1-hydroxypyrene (1-OHP) excretion. Two groups of children (n=11 and 13; 3-6 years old) were chosen: (1) a group from a kindergarten situated near a road with a high traffic density ('polluted' area); (2) a group from a kindergarten situated in a green zone ('non polluted' area). Food consumption was recorded in all children and PAH uptake from foodstuffs was estimated. Ambient air samples were collected on the playground and indoor of kindergartens during 3 days in summer 1997. Soil samples were collected on the playground. Urine samples were collected in the morning and in the evening. Mean outdoor total PAH concentration (sum of 12 individual PAH) in 'polluted' area was 12 times higher than that in 'non polluted' area (22.9 vs. 1.9 ng/m(3)). However, indoor concentrations were similar (3.0 vs. 2.1 ng/m(3)). The same trend was observed for pyrene concentrations. The contribution to the total pyrene absorbed dose from food consumption (estimated daily absorbed dose of 167 and 186 ng, respectively, in 'polluted' and 'non polluted' area) was much more important than that from inhalation (8.4 and 5.4 ng, respectively) in both areas. The estimated daily absorbed doses of pyrene from the soil were 0.061 and 0.104 ng in 'polluted' and 'non polluted' kindergarten, respectively, which correspond to 0.032 and 0.059% of the total absorbed dose. Higher urinary concentrations of 1-OHP were found in children from 'polluted' kindergarten. In conclusion, the food seems to be a main source of the total pyrene and total PAH uptake in small children, even under a relative high PAH air exposure in the city. Pyrene concentration in soil had a negligible contribution to the total pyrene absorbed dose. Usefulness of the urinary 1-OHP as an indicator of the environmental exposure to PAH needs further research.

[Biological and medical monitoring of persons with occupational exposure to fibrous materials]

Health status indicators in 3 groups of workers professionally exposed to fibrous materials and 1 control group have been followed. In spite of the fact that asbestos as a compound of friction elements has been forbidden and replaced by non-asbestos materials, quite important changes in peripheral lymphocytes aberrations we found in persons working with these new materials.

[Chemical load in the population and its evaluation]

Human health is determined by the interplay between heredity and the environment. Air, water, food and soil contain chemical, physical and biological agents some of which are known to be harmful to health. Chemical substances that pose the risk to human health and safety and to the environment are subject to governmental regulation. The regulatory decision-making process and regulatory actions are based on two distinct elements: risk assessment and risk management. Air pollution (outdoor, indoor) is a world problem afflicting densely populated urban centers and heavily industrialised areas. Industrialization and the widespread use of chemicals coupled with modern intensive agricultural practices have raised a global concern about the contamination of soil and water. Three categories of environmental chemical contaminants generally occur in food--natural and synthetic organic compounds and traces of toxic metals. Human health protection against chemical exposure can be realised in three ways. Environmental monitoring assesses exposure to a chemical agent by measuring its concentration in the environment (i.e., air, soil, food, water). Biological monitoring assesses internal exposure to a chemical agent by measuring the chemical, its metabolites or nonadverse biological response in body fluids, tissues, expired air or excreta. Health surveillance entails the periodic medical examinations of exposed humans with the purpose of protecting health and preventing disease.

The effects of subchronical exposure to SO2 on biochemical and hematological parameters in guinea pigs

The effects of subchronical exposure to SO2 (400ppm, 3 hours daily, 28 days) on biochemical and hematological parameters were investigated in guinea pigs. Mostly no significant changes in the values of biochemical parameters and no significant changes in hematological parameters were found. The levels of investigated ions (K+, Na+, Cl-, Ca++, Mg++ and phosphates), proteins (albumines, globulines, total proteins), enzymes (LD, ALT, AST, CK) and other biochemical parameters (urea, creatinine, bilirubin) were not significantly different between groups, with the exception of a significantly higher ALP concentration in the exposed group as compared with controls (2.17 mukat and 1.85 mukat, respectively. It can be concluded that a subchronical exposure to sulphur dioxide mostly did not induce any definite changes in biochemical and hematological parameters in guinea pigs.

[Effect of acute exposure to SO2 on cellular defense mechanisms in the lung (pilot study)]

Sulphur dioxide is one of the most important and most frequent atmospheric pollutant of our environmental setting. In presented pilot-study we describe the influence of acute exposure to sulphur dioxide on alveolar macrophages of guinea pigs. The alveolar macrophages represent the main part of mononuclear phagocytic system, which is responsible for the defence of respiratory tract against foreign compounds. The experimental animals were exposed over three hours to sulphur dioxide with the concentration of about 400 ppm. After exposure we did not find significant changes in phagocytic activity of alveolar macrophages.

[Biological monitoring of chemical exposure]

In this paper we described the biological monitoring as a capable exposure assessment tool that has provided important information used in public health decisions. Biological monitoring is based on determination of biological markers of exposure which are presented as the quantity of a chemical substance or its metabolites or as the deviation of biological parameters (enzyme activity etc.) induced by this substance in exposed humans. The greatest advantage of biological monitoring is the fact that the biological marker of exposure is more directly related to the adverse effects than any environment measurement. Another advantage of biological monitoring is based on the reality that the nonoccupational background exposure (leisure activity, residency, dietary habits, smoking, etc.) may also be expressed in the biological level. Biological parameters can be unfortunately affected by various factors that influence the fate of xenobiotic in vivo. The "BEL" (BTV-biological tolerance value for occupational exposures) is defined as the maximum permissible quantity of a chemical substance or its metabolites or the maximum permissible deviation from the norm of biological parameters during or after exposure. It should be subject to regular revision in the light of new scientific data.

Environmental exposure to polycyclic aromatic hydrocarbons in Czech Republic

1 Objectives of this study were (1) to compare concentrations of individual polycyclic aromatic hydrocarbons (PAH) in air of polluted and nonpolluted area of Czech Republic during winter and summer periods and (2) to verify if urinary 1-hydroxypyrene (1-OHP), as supposed practical biological marker, permits the assessment of spacial and temporal variations in environmental PAH exposure. 2 The study population consisted of three groups: (1) a group of 22 physical exercise students who regularly train outside, from the university situated in a polluted town, spending 14 days in winter and 14 days in summer in 'non-polluted' mountains; (2) a control group of 22 residents from the town and (3) a control group of 18 residents from the mountains. 3 The total PAH concentrations (sum of 13 individual PAH) were 19.3 and 104.6 ng/m3 in town and in mountains, respectively, during summer and 86.6 and 261 ng/m3 during winter. 4 Median 1-OHP levels ranged between 0.03 and 0.13 mumol/mol creatinine for controls and between 0.04 and 0.12 mumol/mol creatinine for students. No relationship was found between pyrene levels in air and group means of urinary 1-OHP. Our results show that other factors (probably PAH in food) contribute in masking air pollution influence on urinary 1-OHP levels in subjects non-occupationally exposed to PAH.

Benzo(a)pyrene-albumin adducts in humans exposed to polycyclic aromatic hydrocarbons in an industrial area of Poland

OBJECTIVES

The interaction of benzo(a)pyrene with serum albumin was measured in an attempt to identify the actual exposure and to evaluate albumin adduct measurements as biomarkers for exposure monitoring.

METHODS

Benzo(a)pyrene-diol-epoxide (BPDE)-albumin adducts were measured by competitive enzyme linked immunosorbent assay (ELISA) in plasma of coke oven plant workers from three plants and from people living in a highly industrialised area of Silesia in Poland. Due to the high air concentrations of polycyclic aromatic hydrocarbons (PAHs) in this area, a control group was selected from a rural non-industrialised area in Poland. Breathing zone air measurements of PAHs were collected from some of the participants.

RESULTS

Coke oven plant workers and non-occupationally exposed people had similar concentrations of albumin adducts whereas the rural controls were significantly lower (2.74 fmol adducts/microgram albumin (SEM 0.124)). The mean concentration of BPDE-albumin adduct in plasma of both the occupational and the environmental groups were significantly higher in the summer samples (4.34 fmol adducts/microgram albumin (SEM 0.335) and 4.55 fmol adducts/microgram albumin (SEM 0.296), respectively) than in the winter samples (3.06 fmol adducts/microgram albumin (SEM 0.187) and 3.04 fmol adducts/microgram albumin (SEM 0.184), respectively) even though the air measurements showed higher concentrations of PAHs in the winter. The statistical analysis did not show any effects of air exposures on concentrations of BPDE-albumin adduct.

CONCLUSIONS

A multiple regression analysis of the measured concentrations of BPDE-albumin adducts for all the groups, during both seasons, indicates that occupational exposures do not contribute significantly to the formation of adducts. In general, the concentrations of albumin adducts found vary within relatively small limits for the two seasons and between the various groups of participants. No extreme differences were found.

Environmental health

A short history of the close connections between human health an ambient environment (environmental health) in the global and national (Czech Republic) sense is presented. Concrete tasks and prospects for the near future are mentioned, including the human ecology education programme.

Distribution of nickel in body fluids and organs of rats chronically exposed to nickel sulphate

1. Male and female rats were given 100 mg Ni L-1 (as nickel sulphate) in drinking water for 6 months. 2. The feeding of nickel was associated with an increased concentration of nickel in body fluids and organs. The highest concentrations of nickel were found in the liver of both male and female rats. In male rats nickel levels decreased in the order: liver > kidney = whole blood = serum > testes > urine. In female rats the decreasing order was similar: liver > kidney = whole blood = serum = plasma > urine > ovaries. 3. No significant differences were found between nickel concentrations in organs (except ovaries), blood and urine of rats exposed for 3 months and those exposed for 6 months indicating the reaching of a steady state of nickel in the rat during long-term exposure. 4. The urinary excretion of the orally administered nickel was only 2% of absorbed dose (supposing 1% Ni absorption).

Renal alterations in female rats following subchronic lead exposure

Female Wistar rats were given 1% or 0.1% lead acetate in drinking water for 2 or 4 months, respectively. Urinary beta 2-microglobulin, N-acetyl-beta-D-glucosaminidase, lactate dehydrogenase and lysozyme were used as markers of tubular dysfunction. Excretion of albumin and glomerular filtration rate were used as indicators of glomerular impairment. Kidney and body weights and morphological changes in the kidney were also studied. Exposure to 1% lead acetate induced a mean blood lead level of 1730 micrograms l-1 and caused only an increase of beta 2-microglobulin excretion and relative kidney weight. Light microscopy of kidney revealed morphological changes mainly in the epithelial cells of the proximal tubules. The role of acetate or reduced water intake on kidney function was excluded because 1% sodium acetate or the restriction of water intake to the volume consumed by the rats of the lead-exposed group was ineffective. Exposure to 0.1% lead acetate induced a blood lead level of 376 micrograms l-1, corresponding to the current level in industry workers, without any sign of nephrotoxicity. Comparison of this study with the results of a previous study on male rats indicates no sex difference in the nephrotoxicity of lead.