Search PubMed⌕ Search

Biomedical subjects

P Hotz

Publications and source records attributed to P Hotz.

At least 37 records · Page 2Linked to original sources
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↗
PubMed1994

[Lymphocyte subpopulations in bronchoalveolar lavage fluid in AIDS].

Lymphocyte subpopulations in peripheral blood and bronchoalveolar lavage fluid (BAL) were examined in 29 patients with AIDS (26 men, three women; median age 32 [16-55] years). Patients in group 1 (n = 12) had no lung disease, in group 2 (n = 11) had Pneumocystis carinii pneumonia, in group 3 (n = 6) had other lung disease. There were 13 men and two women (median age 48 [21-80]) in the control group (bronchoscoped for mild pulmonary symptoms: no abnormal findings in the BAL). Compared with the control group, patients with AIDS had a significant deficiency in helper cells, both in blood (7-23% vs 50%; P < 0.01) as well as in the BAL (7-24% vs 52%; P < 0.001). There was a correlation of the percentage helper cell proportion in peripheral blood and BAL (for both group 1 and 2, rs = 0.75; P < 0.05). The proportion of helper cells in peripheral blood and BAL in AIDS patients was significantly lower in those with than without lung disease (group 1: 23% blood, 24% BAL vs group 2: 9% blood, 7% BAL; group 3: 7% blood, 7% BAL; P < 0.02 blood, P < 0.004 BAL). The percentage proportion of suppressor cells was greater in both blood and BAL in AIDS patients (group 1: blood 47%, BAL 63%; group 2: blood 44%, BAL 76%; group 3: blood 52%, BAL 75%) than in the controls (blood 28%, BAL 33% [P < 0.01], but there was no correlation between peripheral blood and BAL. In addition, the absolute number of suppressor cells in the lavage (30 cells/microliters in group 1 and 3, 65 cells/microliters in group 2) was significantly higher than in the controls (8 cells/microliters).--In AIDS patients there occurs a lymphocytosis in the BAL, while in blood there is a lymphopenia. The concordant decrease in helper cells in blood and BAL is decisive for the severity of any pulmonary infections.

Acquired Immunodeficiency Syndrome↗
PubMed1994

Surveillance of occupational illness through a national poison control center: an approach to reach small-scale enterprises?

A pilot study was performed in order to evaluate the usefulness of the Swiss Toxicological Information Center (STIC) in detecting cases of occupational illness. One hundred and fifty-two symptomatic occupational exposure cases were collected, comprising 3.2% of 4830 cases reported to the STIC between 1 April 1992 and 15 August 1992. In 114 cases a follow-up could be performed by a structured telephone interview. On the basis of these interview data it was estimated that 72% of the cases in small enterprises were reported to the STIC without additional notification to an occupational insurance fund. By contrast, only 28% of the occupational illness cases that occurred in companies employing more than 15 workers were not reported to an occupational insurance fund. This discrepancy could have resulted in part from the fact that occupational insurance in Switzerland is mandatory only for salaried employees, not for self-supporting persons. It is concluded that the monitoring of the occurrence of occupational illnesses in small-scale enterprises must be improved. Poison control centers could play a major role in this respect.

Adult↗
PubMed1994

[The effect of different liner materials on the polymerization of composites].

It has been shown that the polymerization of certain composite filling materials are inhibited by eugenol containing temporary filling materials. The aim of this study was to evaluate the influence of different lining materials (Ketac-Bond, Vitrebond, Dropsin, Dycal, Alkaliner, Super EBA [= control]) on the degree of polymerization of different composites (Brilliant Lux, Brilliant, Herculite, Dual-Cement). The degree of polymerization was characterized by Knoop hardness measurements. The data were analysed by the Wilcoxon test. All lining materials decreased the hardness of the adjacent zone of the tested composites. Brilliant Lux showed a significant decrease (p < 0.01) in hardness until a distance of 200 microns from all lining materials. The chemical curing composite (Brilliant) was generally less influenced in its polymerization by the tested lining materials. Light-activated glass ionomer materials influenced the polymerization at least. It was concluded that light-activated composites seemed to be more influenced in their polymerization by adjacent lining materials than chemically activated ones.

Composite Resins↗
PubMed1993

[Effect of occupation on health behavior and biological cardiovascular risk factors].

Within the framework of the second survey of MONICA-Switzerland (cantons of Vaud and Fribourg; canton of Tessin), the data of 683 working men were analysed to examine the relation between occupation and cardiovascular risk factors. For this purpose, lifestyle factors (smoking, nutritional habits, physical activity, alcohol intake) as well as blood pressure and serum lipoprotein concentrations were compared among 17 different occupational groups. Furthermore, every occupational group was ranked, based on the medians of the mentioned dependent variables. A strong relationship between socioeconomic status (recorded as number of years of schooling completed) and an index for healthy lifestyle was found. However, in some occupational groups a major discrepancy between socioeconomic status respectively lifestyle and measured cardiovascular risk factors (blood pressure, lipoprotein concentrations) was observed. It is therefore hypothesized that unknown occupational factors adversely affect blood pressure and serum lipoproteins for example in physicians, managers and executives whereas the contrary--beneficial effect of unknown occupational factors--is true for example for drivers and bricklayers.

Adult↗
PubMed1993

Serum laminin, hydrocarbon exposure, and glomerular damage.

It has been postulated that occupational exposure to hydrocarbons may damage the kidney and lead to glomerulonephritis and chronic renal failure. As laminin is a ubiquitous basement membrane component that seems to play a central part in the structure and function of basement membranes and as the normal renal filtration process is highly dependent on an intact glomerular basement membrane, the serum laminin concentration was examined in a population of workers exposed to hydrocarbons. The hydrocarbon exposure was assessed by exposure surrogates (exposure duration and exposure score). An interaction between occupational exposure to hydrocarbons and hypertension increased the laminin concentration whereas the laminin concentration decreased in workers exposed for a long time probably because of a selection effect. In a subgroup of printers exposed to toluene whose hippuric acid excretion had been recorded for several years this interaction was confirmed when the hippuric acid excretion was substituted for the other exposure indices. In the exposed group, the age-related decline in creatinine clearance was accelerated. These results seem to confirm that occupational exposure to hydrocarbons is a non-specific factor that may promote a deterioration of renal function.

Adult↗