PubMed Health⌕ Search

Biomedical subjects

P Hotz

Publications and source records attributed to P Hotz.

At least 19 recordsLinked to original sources
PubMed1998

Interleukin 1 alpha hematological examination in mechanics exposed to low benzene concentrations.

OBJECT: To examine the hypothesis of Renz and Kalf relative to the involvement of interleukin 1 alpha (IL-1 alpha) in the development of anemia in benzene-exposed workers. According to this hypothesis, benzene inhibits the cleavage of the IL-1 alpha precursor (proIL-1 alpha) to mature IL-1 alpha and the lack of this cytokine is responsible for benzene-induced bone marrow suppression. This inhibition of the processing of proIL-1 alpha is attributed to an inhibition of calpain. METHOD: Selection of a population of mechanics exposed to low levels of benzene from fuels, assessment of usual exposure and lifetime exposure duration, and measurements of concentrations of workplace-air benzene and urinary benzene metabolites. Determination of IL-1 alpha concentrations was done by a whole-blood assay after lipopolysaccharide stimulation and a hematological examination was carried out. Statistical analysis considered several possible confounding factors, particularly smoking and drinking habits. DESIGN: Cross-sectional study. RESULTS: The level of exposure of the mechanics to benzene from fuels was mostly well below 1 ppm. IL-1 alpha production was not decreased in mechanics exposed to benzene from fuels, and no correlation between IL-1 alpha concentrations and red blood cell counts appeared. With the exception of a slight decrease in red blood cell counts in mechanics, no hint of a toxic effect of exposure on hematological parameters was found. CONCLUSIONS: The hypothesis of Renz and Kalf could not be confirmed. Although the low level exposure of the study population and methodological factors are possible explanations, it cannot be excluded that the hypothesis of Renz and Kalf is not generalizable to benzene-exposed humans. Presently, one cannot advise the measurement of IL-1 alpha production for biological effect monitoring of workers exposed to low concentrations of benzene.

Adult↗
PubMed1997

Biological monitoring of vehicle mechanics and other workers exposed to low concentrations of benzene.

It has been suggested that the threshold limit value (TLV) for the time-weighted average (TWA), of benzene be lowered because of its possible leukemogenic effect at low exposure concentrations. This requires the development of new methods of biological monitoring. In this cross-sectional study the diagnostic power of blood and breath benzene and of urinary phenol, catechol, hydroquinone, S-phenylmercapturic acid, and muconic acid were compared in a population of 410 male workers exposed to benzene in garages, in two coke plants, and in a by-product plant. Benzene exposure was assessed by personal air sampling (charcoal tube and passive dosimeter). In all, 95% of the workers were exposed to less than 0.5 ppm benzene. According to the multiple regression equation, the muconic acid and S-phenylmercapturic acid concentrations detected in nonsmokers exposed to 0.5 ppm benzene were 0.3 mg/g and 6 micrograms/g, respectively (range 0.2-0.6 mg/g and 1.2-8.5 micrograms/g, respectively). With muconic acid very few false-positive test results were found, and this determination remained reliable even around a cutoff level of 0.1 ppm benzene. Moreover, the diagnostic power of this test proved to be good even when diluted or concentrated urine samples were not excluded. S-Phenylmercapturic acid (S-PMA) also performed fairly well. Blood and breath benzene as well as urinary phenol (PH) and hydroquinone (HQ) were clearly less suitable biomarkers than muconic acid (MA). Catechol (CA) was not associated with occupational benzene exposure. According to the results of biological monitoring, the skin resorption of benzene from gasoline or other fuels seems negligible. Correlation, multiple regression, and likelihood ratios consistently showed that MA and S-PMA concentrations were fairly good indicators of benzene exposure in the 0.1- to 1-ppm range, even in a population comprising both smokers and nonsmokers. PH, HQ, CA, and blood and breath benzene were less suitable, if at all, in the same exposure range.

Adult↗
PubMed1997

Relationships between smoking habits, smoking-associated hematological changes, and urinary benzene metabolites.

It has been suggested that benzene metabolites might be good indicators of smoking. Moreover, benzene could stimulate the neutrophil lineage while depressing the lymphocytic and erythroid lineages, possibly by an interference with cytokines. The effect on the neutrophil lineage could explain the smokers' leukocytosis, the mechanism of which is presently unknown. Therefore, the usefulness of benzene metabolites as indicators of smoking was compared to that of cotinine and thiocyanate, and the relationships between benzene metabolites, the hematological parameters of smokers, and interleukin 1 alpha production were examined. The results show that benzene metabolites are not better indicators of smoking status than cotinine or thiocyanate. Furthermore, it seems unlikely that the smokers' leukocytosis is benzene induced.

Adult↗
PubMed1997

Hematopoietic and lymphatic malignancies in vehicle mechanics.

Although it is generally acknowledged that benzene causes leukemia, especially acute myeloid leukemia, considerable divergences persist in the assessment of the leukemia risk due to occupational low-level benzene exposure. Specifically, the risk for vehicle mechanics is considered by some authors as being nondetectable with epidemiologic methods, whereas others calculated that the incidence rate of leukemia (all types) in vehicle mechanics is increased more than 60 times. The purpose of this review is to examine the publications on this topic in light of criteria for causal inference and to discuss the possible role of bias, confounding factors, and chance. The results of this analysis reveal that there are surprisingly few epidemiologic observations supporting an increased incidence of leukemia in vehicle mechanics. Apparently, publications suggesting a leukemogenic effect of low-level benzene exposure in garage mechanics are more often quoted than their negative counterparts, although they are not better designed.

Adolescent↗
PubMed1996

Effect of oral protein load on urinary protein excretion in workers exposed to cadmium and to lead.

An acute oral protein load causes a transient hyperfiltration that might reveal a loss of glomerular permselectivity properties. The effect of an oral protein load on the urinary excretion rate of albumin (UAE), beta-2-microglobulin (UB2MGE), and retinol-binding protein (URBPE) was thus examined in cadmium- and lead-exposed workers. The results show a transient increase in UB2MGE and URBPE without relevant changes in UAE. These changes were also observed in control groups and are due to competitive inhibition of tubular protein reabsorption by absorbed cationic amino acids. These results do not support the hypothesis that the acute protein load test is of great utility in revealing a silent glomerular filtration disturbance in lead- or cadmium-exposed workers. However, it might disclose imminent renal tubular dysfunction in cadmium workers not yet showing increased microproteinuria under baseline conditions.

Adult↗
PubMed1996

Development and validation of new screening tests for nephrotoxic effects.

Within the framework of an European Commission-funded project, groups of industrial workers exposed to heavy metals (cadmium, mercury and lead) or solvents were studied together with corresponding control groups. Eighty-one measurements were carried out on urine and serum samples and the scientific results together with individual questionnaire information were entered into a central database. Data obtained was assessed centrally and individually in subsidiary studies. The measurable contributions were assessed either singly or in combination, of smoking, gender, metal exposure and site, to nephrotoxicity. The potential value of each test as an indicator of nephrotoxicity was then assessed on the basis of sensitivity and specificity. A number of new tests including prostaglandins and for extracellular matrix components were investigated as well as established tests for renal damage and dysfunction. The data obtained from this comprehensive study emphasises the value of noninvasive biomarkers for the early detection of nephrotoxicity due to environmental toxins. The urinary profile varied with the type of environmental/occupational toxin. By careful selection of a small panel of markers they can be used to indicate the presence of renal damage, the principal region affected, and to monitor the progress of disease and damage. Biomarkers were also used to confirm and tentatively establish safe exposure levels to nephrotoxins.

Biomarkers↗
PubMed1995

A new non-instrumental technique for cleaning and filling root canals.

The aim of this in vitro study was to test the ability of a novel non-instrumental technique to prepare and obturate root canals. Cleaning of the root canal system was achieved with a device which was able to develop, under reduced pressure, controlled cavitation. The same device was used for proper drying and subsequent obturation of the root canal system. A total of 55 freshly extracted molars with 120 canals were treated either by the step-back technique and lateral condensation of gutta-percha and AH26 as a sealer or by the new device. The teeth were then sectioned horizontal to the long axis of the root canal and examined by light microscopy. The cross-sectional area, area with residual pulpal tissue and voids were assessed morphometrically. Overall, the treatment with the new device resulted in similar cleanliness and obturation quality when compared with the control group. Total treatment time using the new non-instrumental technique, however, was less than half of that using hand instrumentation.

Analysis of Variance↗
PubMed1995

Subclinical signs of kidney dysfunction following short exposure to silica in the absence of silicosis.

Signs of kidney dysfunction detectable in urinary protein excretion were searched for in a group of 86 silica-exposed workers who were compared to 86 control subjects matched for age, smoking status and body mass index. No worker had any clinical, spirometric or radiographic sign of silicosis, and exposure duration averaged 15.2 months (range: 11-20). An increase in the urinary excretion of albumin, transferrin, retinol-binding protein and N-acetyl-beta-D-glucosaminidase was found in the exposed group, and the prevalences of pathological values were also elevated in this group. By contrast, both groups had similar serum levels of creatinine and beta 2-microglobulin. These results strongly suggest that occupational exposure to silica may lead to subclinical renal effects after less than 2 years and in the absence of silicosis.

Adult↗
PubMed1995

In vivo diagnosis of fissure caries using a new electrical resistance monitor.

The aim of this investigation was to study the accuracy of a newly developed electrical resistance monitor in diagnosing occlusal fissure caries in vivo in teeth without cavitation. The electrical resistance was measured in vivo on human third molars without existing restorations and without any macroscopic carious cavitation. Data from 41 sites on 26 occlusal surfaces were obtained. After measurement, the teeth were extracted, histologically prepared, and serially sectioned perpendicular to the occlusal surface and examined for the presence of caries. Nineteen sites had no caries, 7 had enamel caries, and 15 sites showed dentinal caries, 4 of which deep dentinal caries. For the diagnosis of occlusal caries with the electrical resistance monitor, the specificity was 0.77, the sensitivity 0.93, and the accuracy 0.83. Likelihood ratios for four diagnostic levels (no caries, enamel caries, dentinal caries, and deep dentinal caries) were 0.09, 0, 3.47, and 4.16, respectively. Diagnosis of occlusal caries using conventional bite-wing radiographs showed a specificity of 0.77, a sensitivity of 0.62, and an accuracy of 0.71. The electrical resistance monitor was well suited to detect in vivo occlusal caries under clinically intact fissures. The rather high value (0.23) of false-positive ratings, however, might lead to a substantial number of sound teeth being restored unnecessarily. Substantial improvement of occlusal, caries diagnosis may be achieved by combining this method with others.

Adult↗
PubMed1995

[The cariostatic mechanisms of action of fluorides. A review].

In the past the inhibition of caries by fluorides was ascribed to the reduced solubility of enamel due to the incorporation of F- into the enamel mineral. During the last years the understanding of the cariostatic mechanism has changed fundamentally. Based on these new findings the loosely bound fluorides, which are present in the surroundings of the teeth after application of topicals, are regarded as decisive for the caries preventing effect by causing an inhibition of demineralization, enhancing the remineralization process and supporting the precipitation of CaF2. The formation of CaF2 is induced after application of topicals, and the material stays relatively stable in the mouth, due to adsorbed HPO4(2-) ions at the surface of CaF2. During the cariogenic challenge, CaF2 releases F- ions due to the reduced concentration of HPO4(2-) ions at acidic pH values. The CaF2 therefore functions as a pH-controlled F(-)-reservoir and is the most important supplier of free F- ions during the cariogenic challenge.

Dental Enamel↗
PubMed1995

[Personnel and instrumental differences in the treatment of root surfaces. A comparison on a phantom model].

The treatment of root surfaces in periodontal lesions with mechanical instruments is becoming more and more popular as an alternative to the conventional treatment with curets. In this in-vitro study a phantom head with a simulated periodontitis was used. The aim of this investigation was to determine the percentage of the subgingival non-treated root surfaces after treatment with different instruments and by different persons. Newly developed mechanical file instruments (Rootshape) were tested. Hand curets served as control group. The treatment of the teeth was carried out by three groups, each including 4 people. Group one were dental hygienists (DH), group two dentists with (Spez) and group three dentist without (Zaz) experience in the therapy of periodontal diseases. They were asked to perform a scaling and root planing on six teeth (16, 21, 24, 36, 41, 44) both with curets and Rootshape files. The size of the non-treated areas was subsequently determined planimetrically and expressed as percentage of the entire subgingival root surface. Independent of the group the percentage after file treatment was significantly lower (mean 9.85 +/- 7.78%) than that after curet-treatment (mean 14.74 +/- 10.20%). Significant differences were found when the three groups were compared after treatment either with files or curets (DH 9.61 +/- 8.02%, Spez 12.11 +/- 8.01%, Zaz 15.18 +/- 11.01%; p < 0.001). Zaz working with files achieved as good results as DH or Spez with curets (p < or = 0.05). The results indicate that the files represent an alternative to hand instruments concerning the accessibility of root surfaces.

Dental Hygienists↗
PubMed1995

The relative caries-inhibiting efficacy of amine fluoride and sodium fluoride in compatible dentifrices--results of a consensus conference.

A conference concerning the caries-inhibiting efficacy of dentifrices that contain amine and sodium fluorides compared relevant clinical studies and found that both fluoride compounds contribute to the maintenance of dental health. Because of the differing test conditions, the study results cannot, however, be compared. Thus, there is no definite scientific proof of the superiority of one fluoride compound, and no such proof will exist until dentifrices containing amine fluoride and sodium fluoride are tested in a direct clinical comparison.

Amines↗
PubMed1994

Occupational hydrocarbon exposure and chronic nephropathy.

This review aims at discussing the questions raised by the hydrocarbon-related chronic nephropathy and its possible consequence, the hydrocarbon-related chronic renal failure. It has been attempted to adopt the point of view of the clinician. Therefore, the most important part of the review is devoted to a presentation and an analysis of the available data on humans. The main features of the available studies on human subjects are presented, their conclusions discussed in the light of the possible methodological flaws, and practical conclusions drawn. After a discussion of the main difficulties encountered for selecting the suitable exposure indicator, the studies are discussed in order of decreasing quality of the study design (cohort, case-control, cross-sectional studies, and the case reports). It is concluded that a great deal of controversies about chronic hydrocarbon-related nephropathy is explained by differences in the study design and that hydrocarbon-induced nephropathy is probably more than a mere hypothesis, although a causal relationship has not yet been proven. Finally, some practical consequences for dealing with a hydrocarbon-exposed patient diagnosed with a kidney disease and the need for further research are discussed.

Epidemiologic Methods↗